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1996-10-13
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257KB
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6,495 lines
This file contains patches that transform the baseline version into
the amiga version. Assuming that you have unarchived the baseline
version in the current directory, just run the command:
patch -p1 -E -b .pbak <diff-file
where 'diff-file' is this patch file. After running patch you should
remove all the generated *.pbak files, and look for any *.rej files
that indicate a problem patching the baseline source.
diff -rup --new-file baseline/fsf/bison/BeOS.diffs amiga/fsf/bison/BeOS.diffs
--- baseline/fsf/bison/BeOS.diffs Wed Dec 31 17:00:00 1969
+++ amiga/fsf/bison/BeOS.diffs Sat Sep 28 00:00:00 1996
@@ -0,0 +1,324 @@
+This patch works around current bugs in the BeOS shell that affect
+configure, and also patch up some Makefile targets that are not
+yet fully supported.
+
+============================================================================
+
+diff -rc bison-ref/Makefile.in bison/Makefile.in
+*** bison-ref/Makefile.in Thu Sep 12 16:51:51 1996
+--- bison/Makefile.in Mon Sep 16 01:47:29 1996
+***************
+*** 107,113 ****
+ warshall.o version.o \
+ getopt.o getopt1.o $(ALLOCA)
+
+! all: bison bison.info bison.s1 bison.guide bison.dvi bison.ps
+
+ Makefile: Makefile.in config.status
+ ./config.status
+--- 107,113 ----
+ warshall.o version.o \
+ getopt.o getopt1.o $(ALLOCA)
+
+! all: bison bison.info bison.s1 bison.guide
+
+ Makefile: Makefile.in config.status
+ ./config.status
+***************
+*** 142,149 ****
+ for f in bison.info*; \
+ do $(INSTALL_DATA) $$f $(infodir)/$$f; done
+ $(INSTALL_DATA) bison.guide $(guidedir)/bison.guide
+! $(INSTALL_DATA) bison.dvi $(dvidir)/bison.dvi
+! $(INSTALL_DATA) bison.ps $(psdir)/bison.ps
+ $(INSTALL_DATA) $(srcdir)/bison.1 $(mandir)/bison.$(manext)
+
+ # Make sure all installation directories, e.g. $(bindir) actually exist by
+--- 142,149 ----
+ for f in bison.info*; \
+ do $(INSTALL_DATA) $$f $(infodir)/$$f; done
+ $(INSTALL_DATA) bison.guide $(guidedir)/bison.guide
+! # $(INSTALL_DATA) bison.dvi $(dvidir)/bison.dvi
+! # $(INSTALL_DATA) bison.ps $(psdir)/bison.ps
+ $(INSTALL_DATA) $(srcdir)/bison.1 $(mandir)/bison.$(manext)
+
+ # Make sure all installation directories, e.g. $(bindir) actually exist by
+diff -rc bison-ref/configure bison/configure
+*** bison-ref/configure Tue Sep 10 03:05:11 1996
+--- bison/configure Mon Sep 16 01:42:45 1996
+***************
+*** 599,605 ****
+ yes;
+ #endif
+ EOF
+! if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:603: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+ ac_cv_prog_gcc=yes
+ else
+ ac_cv_prog_gcc=no
+--- 599,605 ----
+ yes;
+ #endif
+ EOF
+! if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:603: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; } | egrep yes >/dev/null 2>&1; then
+ ac_cv_prog_gcc=yes
+ else
+ ac_cv_prog_gcc=no
+***************
+*** 737,743 ****
+ Syntax Error
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:741: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ :
+--- 737,743 ----
+ Syntax Error
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:741: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ :
+***************
+*** 752,758 ****
+ Syntax Error
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:756: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ :
+--- 752,758 ----
+ Syntax Error
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:756: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ :
+***************
+*** 783,789 ****
+ #include <minix/config.h>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:787: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+--- 783,789 ----
+ #include <minix/config.h>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:787: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+***************
+*** 852,858 ****
+ #include "confdefs.h"
+ main(){return(0);}
+ EOF
+! { (eval echo configure:856: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ ac_cv_c_cross=no
+ else
+--- 852,858 ----
+ #include "confdefs.h"
+ main(){return(0);}
+ EOF
+! { (eval echo configure:856: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ ac_cv_c_cross=no
+ else
+***************
+*** 878,884 ****
+ #include <float.h>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:882: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+--- 878,884 ----
+ #include <float.h>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:882: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+***************
+*** 943,949 ****
+ exit (0); }
+
+ EOF
+! { (eval echo configure:947: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ :
+ else
+--- 943,949 ----
+ exit (0); }
+
+ EOF
+! { (eval echo configure:947: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ :
+ else
+***************
+*** 975,981 ****
+ #include <$ac_hdr>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:979: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+--- 975,981 ----
+ #include <$ac_hdr>
+ EOF
+ ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+! { (eval echo configure:979: \"$ac_try\") 1>&5; xxx=`(eval $ac_try 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ ac_err=`grep -v '^ *+' conftest.out`
+ if test -z "$ac_err"; then
+ rm -rf conftest*
+***************
+*** 1055,1061 ****
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1059: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+ rm -rf conftest*
+ ac_cv_c_const=yes
+ else
+--- 1055,1061 ----
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1059: \"$ac_compile\") 1>&5; xxx=`(eval $ac_compile 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; then
+ rm -rf conftest*
+ ac_cv_c_const=yes
+ else
+***************
+*** 1090,1096 ****
+ char *p = alloca(2 * sizeof(int));
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1094: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+ rm -rf conftest*
+ ac_cv_header_alloca_h=yes
+ else
+--- 1090,1096 ----
+ char *p = alloca(2 * sizeof(int));
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1094: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; then
+ rm -rf conftest*
+ ac_cv_header_alloca_h=yes
+ else
+***************
+*** 1138,1144 ****
+ char *p = (char *) alloca(1);
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1142: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+ rm -rf conftest*
+ ac_cv_func_alloca=yes
+ else
+--- 1138,1144 ----
+ char *p = (char *) alloca(1);
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1142: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; then
+ rm -rf conftest*
+ ac_cv_func_alloca=yes
+ else
+***************
+*** 1226,1232 ****
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1230: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+ rm -rf conftest*
+ eval "ac_cv_func_$ac_func=yes"
+ else
+--- 1226,1232 ----
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1230: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; then
+ rm -rf conftest*
+ eval "ac_cv_func_$ac_func=yes"
+ else
+***************
+*** 1277,1283 ****
+ exit (find_stack_direction() < 0);
+ }
+ EOF
+! { (eval echo configure:1281: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ ac_cv_c_stack_direction=1
+ else
+--- 1277,1283 ----
+ exit (find_stack_direction() < 0);
+ }
+ EOF
+! { (eval echo configure:1281: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }
+ if test -s conftest && (./conftest; exit) 2>/dev/null; then
+ ac_cv_c_stack_direction=1
+ else
+***************
+*** 1325,1331 ****
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1329: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+ rm -rf conftest*
+ eval "ac_cv_func_$ac_func=yes"
+ else
+--- 1325,1331 ----
+
+ ; return 0; }
+ EOF
+! if { (eval echo configure:1329: \"$ac_link\") 1>&5; xxx=`(eval $ac_link 2>&5 ; echo $?)` ; test "$xxx" = "0" ; }; then
+ rm -rf conftest*
+ eval "ac_cv_func_$ac_func=yes"
+ else
+***************
+*** 1367,1375 ****
+ EOF
+ # Ultrix sh set writes to stderr and can't be redirected directly,
+ # and sets the high bit in the cache file unless we assign to the vars.
+! (set) 2>&1 |
+ sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/\1=\${\1='\2'}/p" \
+! >> confcache
+ if cmp -s $cache_file confcache; then
+ :
+ else
+--- 1367,1375 ----
+ EOF
+ # Ultrix sh set writes to stderr and can't be redirected directly,
+ # and sets the high bit in the cache file unless we assign to the vars.
+! (set) >cache.tmp 2>&1
+ sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/\1=\${\1='\2'}/p" \
+! <cache.tmp >> confcache
+ if cmp -s $cache_file confcache; then
+ :
+ else
+***************
+*** 1380,1386 ****
+ echo "not updating unwritable cache $cache_file"
+ fi
+ fi
+! rm -f confcache
+
+ trap 'rm -fr conftest* confdefs* core core.* *.core $ac_clean_files; exit 1' 1 2 15
+
+--- 1380,1386 ----
+ echo "not updating unwritable cache $cache_file"
+ fi
+ fi
+! rm -f confcache cache.tmp
+
+ trap 'rm -fr conftest* confdefs* core core.* *.core $ac_clean_files; exit 1' 1 2 15
+
diff -rup --new-file baseline/fsf/bison/Makefile.in amiga/fsf/bison/Makefile.in
--- baseline/fsf/bison/Makefile.in Sat May 11 12:17:40 1996
+++ amiga/fsf/bison/Makefile.in Sat Sep 28 00:00:00 1996
@@ -27,6 +27,8 @@ INSTALL = @INSTALL@
INSTALL_PROGRAM = @INSTALL_PROGRAM@
INSTALL_DATA = @INSTALL_DATA@
MAKEINFO = makeinfo
+TEXI2DVI = texi2dvi
+DVIPS = dvips
# Things you might add to DEFS:
# -DSTDC_HEADERS If you have ANSI C headers and libraries.
@@ -35,8 +37,8 @@ MAKEINFO = makeinfo
# -DHAVE_STRERROR If you have strerror function.
DEFS = @DEFS@
-CFLAGS = -g
-LDFLAGS =
+CFLAGS = @CFLAGS@
+LDFLAGS = @LDFLAGS@
LIBS = @LIBS@
@@ -56,6 +58,15 @@ datadir = $(prefix)/share
# where the info files go
infodir = $(prefix)/info
+# where the guide files go
+guidedir = $(prefix)/guide
+
+# where the dvi files go
+dvidir = $(prefix)/dvi
+
+# where the ps files go
+psdir = $(prefix)/ps
+
# where manual pages go and what their extensions should be
mandir = $(prefix)/man/man$(manext)
manext = 1
@@ -70,16 +81,18 @@ DISTFILES = COPYING ChangeLog Makefile.i
output.c print.c reader.c reduce.c symtab.c version.c \
warshall.c files.h gram.h lex.h machine.h new.h state.h \
symtab.h system.h types.h bison.cld build.com vmsgetargs.c \
- vmshlp.mar README INSTALL NEWS bison.texinfo bison.info* texinfo.tex \
- getopt.c getopt.h getopt1.c alloca.c mkinstalldirs install-sh
+ vmshlp.mar README INSTALL NEWS bison.texinfo bison.info* \
+ bison.guide bison.dvi bison.ps \
+ texinfo.tex getopt.c getopt.h getopt1.c alloca.c mkinstalldirs install-sh
SHELL = /bin/sh
# This rule allows us to supply the necessary -D options
# in addition to whatever the user asks for.
+# ADE-local: Removed -I$(srcdir)/../include since it points nowhere.
.c.o:
- $(CC) -c $(DEFS) -I$(srcdir)/../include $(CPPFLAGS) $(CFLAGS) $<
+ $(CC) -c $(DEFS) $(CPPFLAGS) $(CFLAGS) $<
# names of parser files
PFILE = bison.simple
@@ -94,7 +107,7 @@ OBJECTS = LR0.o allocate.o closure.o con
warshall.o version.o \
getopt.o getopt1.o $(ALLOCA)
-all: bison bison.info bison.s1
+all: bison bison.info bison.s1 bison.guide bison.dvi bison.ps
Makefile: Makefile.in config.status
./config.status
@@ -119,26 +132,30 @@ distclean: clean
rm -f Makefile config.status
realclean: distclean
- rm -f TAGS *.info*
+ rm -f TAGS *.info* *.guide *.dvi *.ps
# Most of these deps are in case using RCS.
install: all bison.1 $(srcdir)/$(PFILE) $(srcdir)/$(PFILE1) installdirs uninstall
$(INSTALL_PROGRAM) bison $(bindir)/bison
$(INSTALL_DATA) bison.s1 $(datadir)/$(PFILE)
$(INSTALL_DATA) $(srcdir)/$(PFILE1) $(datadir)/$(PFILE1)
- cd $(srcdir); for f in bison.info*; \
+ for f in bison.info*; \
do $(INSTALL_DATA) $$f $(infodir)/$$f; done
- -$(INSTALL_DATA) $(srcdir)/bison.1 $(mandir)/bison.$(manext)
+ $(INSTALL_DATA) bison.guide $(guidedir)/bison.guide
+ $(INSTALL_DATA) bison.dvi $(dvidir)/bison.dvi
+ $(INSTALL_DATA) bison.ps $(psdir)/bison.ps
+ $(INSTALL_DATA) $(srcdir)/bison.1 $(mandir)/bison.$(manext)
# Make sure all installation directories, e.g. $(bindir) actually exist by
# making them if necessary.
installdirs:
- -sh $(srcdir)/mkinstalldirs $(bindir) $(datadir) $(libdir) $(infodir) $(mandir)
+ -sh $(srcdir)/mkinstalldirs $(bindir) $(datadir) $(libdir) $(infodir) $(guidedir) $(mandir) $(dvidir) $(psdir)
uninstall:
rm -f $(bindir)/bison
-cd $(datadir); rm -f $(PFILE) $(PFILE1)
rm -f $(mandir)/bison.$(manext) $(infodir)/bison.info*
+ rm -f $(guidedir)/bison.guide $(dvidir)/bison.dvi $(psdir)/bison.ps
check:
@echo "No checks implemented (yet)."
@@ -149,7 +166,7 @@ bison: $(OBJECTS)
# We don't use $(srcdir) in this rule
# because it is normally used in the master source dir
# in which configure has not been run.
-dist: bison.info
+dist: bison.info bison.guide bison.dvi bison.ps
echo bison-`sed -e '/version_string/!d' -e 's/[^0-9.]*\([0-9.]*\).*/\1/' -e q version.c` > .fname
-rm -rf `cat .fname`
mkdir `cat .fname`
@@ -160,7 +177,16 @@ dist: bison.info
-rm -rf `cat .fname` .fname
bison.info: bison.texinfo
- $(MAKEINFO) $(srcdir)/bison.texinfo
+ $(MAKEINFO) -I$(srcdir) $(srcdir)/bison.texinfo -o $@
+
+bison.guide: bison.texinfo
+ $(MAKEINFO) --amiga $(srcdir)/bison.texinfo -o $@
+
+bison.dvi: bison.texinfo
+ $(TEXI2DVI) $?
+
+bison.ps: bison.dvi
+ $(DVIPS) -o $@ $?
TAGS: *.c *.h
etags *.c *.h
diff -rup --new-file baseline/fsf/bison/Product-Info amiga/fsf/bison/Product-Info
--- baseline/fsf/bison/Product-Info Wed Dec 31 17:00:00 1969
+++ amiga/fsf/bison/Product-Info Sat Sep 28 00:00:00 1996
@@ -0,0 +1,26 @@
+.name
+bison
+.fullname
+GNU parser generator
+.type
+Programmer Tool
+.short
+GNU parser generator yacc replacement
+.description
+Bison is a parser generator in the style of yacc (1). It should be
+upwardly compatible with input files designed for yacc. Input files
+should follow the yacc convention of ending in ".y". Unlike yacc, the
+generated files do not have fixed names, but instead use the prefix of
+the input file. For instance, a grammar description file named
+parse.y would produce the generated parser in a file named
+parse.tab.c, instead of yacc 's y.tab.c.
+.version
+1.25
+.author
+Free Software Foundation
+.requirements
+Binary version requires ixemul.library.
+.distribution
+GNU Public License
+.described-by
+Fred Fish (fnf@ninemoons.com)
diff -rup --new-file baseline/fsf/bison/bison.1 amiga/fsf/bison/bison.1
--- baseline/fsf/bison/bison.1 Mon Aug 21 10:15:28 1995
+++ amiga/fsf/bison/bison.1 Sat Sep 28 00:00:00 1996
@@ -325,9 +325,9 @@ The long-named options can be introduced
for compatibility with previous releases. Eventually support for `+'
will be removed, because it is incompatible with the POSIX.2 standard.
.SH FILES
-/usr/local/lib/bison.simple simple parser
+/ade/lib/bison.simple simple parser
.br
-/usr/local/lib/bison.hairy complicated parser
+/ade/lib/bison.hairy complicated parser
.SH SEE ALSO
.IR yacc (1)
.br
diff -rup --new-file baseline/fsf/bison/bison.info amiga/fsf/bison/bison.info
--- baseline/fsf/bison/bison.info Sat Feb 17 09:46:08 1996
+++ amiga/fsf/bison/bison.info Wed Dec 31 17:00:00 1969
@@ -1,129 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-Indirect:
-bison.info-1: 1169
-bison.info-2: 50097
-bison.info-3: 97816
-bison.info-4: 147524
-bison.info-5: 195081
-
-Tag Table:
-(Indirect)
-Node: Top1169
-Node: Introduction8402
-Node: Conditions9675
-Node: Copying11141
-Node: Concepts30294
-Node: Language and Grammar31327
-Node: Grammar in Bison36343
-Node: Semantic Values38267
-Node: Semantic Actions40368
-Node: Bison Parser41551
-Node: Stages43861
-Node: Grammar Layout45144
-Node: Examples46401
-Node: RPN Calc47536
-Node: Rpcalc Decls48510
-Node: Rpcalc Rules50097
-Node: Rpcalc Input51897
-Node: Rpcalc Line53358
-Node: Rpcalc Expr54473
-Node: Rpcalc Lexer56418
-Node: Rpcalc Main58977
-Node: Rpcalc Error59355
-Node: Rpcalc Gen60360
-Node: Rpcalc Compile61508
-Node: Infix Calc62383
-Node: Simple Error Recovery65090
-Node: Multi-function Calc66977
-Node: Mfcalc Decl68544
-Node: Mfcalc Rules70567
-Node: Mfcalc Symtab71947
-Node: Exercises78121
-Node: Grammar File78627
-Node: Grammar Outline79395
-Node: C Declarations80129
-Node: Bison Declarations80709
-Node: Grammar Rules81121
-Node: C Code81581
-Node: Symbols82511
-Node: Rules87593
-Node: Recursion89232
-Node: Semantics90943
-Node: Value Type92040
-Node: Multiple Types92712
-Node: Actions93728
-Node: Action Types96513
-Node: Mid-Rule Actions97816
-Node: Declarations103385
-Node: Token Decl104704
-Node: Precedence Decl106701
-Node: Union Decl108252
-Node: Type Decl109096
-Node: Expect Decl110002
-Node: Start Decl111548
-Node: Pure Decl111926
-Node: Decl Summary113240
-Node: Multiple Parsers116755
-Node: Interface118249
-Node: Parser Function119121
-Node: Lexical119956
-Node: Calling Convention121362
-Node: Token Values124091
-Node: Token Positions125239
-Node: Pure Calling126131
-Node: Error Reporting129088
-Node: Action Features131213
-Node: Algorithm134864
-Node: Look-Ahead137157
-Node: Shift/Reduce139289
-Node: Precedence142200
-Node: Why Precedence142851
-Node: Using Precedence144706
-Node: Precedence Examples145674
-Node: How Precedence146375
-Node: Contextual Precedence147524
-Node: Parser States149315
-Node: Reduce/Reduce150558
-Node: Mystery Conflicts154119
-Node: Stack Overflow157505
-Node: Error Recovery158878
-Node: Context Dependency164014
-Node: Semantic Tokens164862
-Node: Lexical Tie-ins167879
-Node: Tie-in Recovery169427
-Node: Debugging171599
-Node: Invocation174950
-Node: Bison Options175613
-Node: Option Cross Key179726
-Node: VMS Invocation180608
-Node: Table of Symbols181392
-Node: Glossary188790
-Node: Index195081
-
-End Tag Table
diff -rup --new-file baseline/fsf/bison/bison.info-1 amiga/fsf/bison/bison.info-1
--- baseline/fsf/bison/bison.info-1 Sat Feb 17 09:46:05 1996
+++ amiga/fsf/bison/bison.info-1 Wed Dec 31 17:00:00 1969
@@ -1,1068 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-File: bison.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
-
- This manual documents version 1.25 of Bison.
-
-* Menu:
-
-* Introduction::
-* Conditions::
-* Copying:: The GNU General Public License says
- how you can copy and share Bison
-
-Tutorial sections:
-* Concepts:: Basic concepts for understanding Bison.
-* Examples:: Three simple explained examples of using Bison.
-
-Reference sections:
-* Grammar File:: Writing Bison declarations and rules.
-* Interface:: C-language interface to the parser function `yyparse'.
-* Algorithm:: How the Bison parser works at run-time.
-* Error Recovery:: Writing rules for error recovery.
-* Context Dependency:: What to do if your language syntax is too
- messy for Bison to handle straightforwardly.
-* Debugging:: Debugging Bison parsers that parse wrong.
-* Invocation:: How to run Bison (to produce the parser source file).
-* Table of Symbols:: All the keywords of the Bison language are explained.
-* Glossary:: Basic concepts are explained.
-* Index:: Cross-references to the text.
-
- -- The Detailed Node Listing --
-
-The Concepts of Bison
-
-* Language and Grammar:: Languages and context-free grammars,
- as mathematical ideas.
-* Grammar in Bison:: How we represent grammars for Bison's sake.
-* Semantic Values:: Each token or syntactic grouping can have
- a semantic value (the value of an integer,
- the name of an identifier, etc.).
-* Semantic Actions:: Each rule can have an action containing C code.
-* Bison Parser:: What are Bison's input and output,
- how is the output used?
-* Stages:: Stages in writing and running Bison grammars.
-* Grammar Layout:: Overall structure of a Bison grammar file.
-
-Examples
-
-* RPN Calc:: Reverse polish notation calculator;
- a first example with no operator precedence.
-* Infix Calc:: Infix (algebraic) notation calculator.
- Operator precedence is introduced.
-* Simple Error Recovery:: Continuing after syntax errors.
-* Multi-function Calc:: Calculator with memory and trig functions.
- It uses multiple data-types for semantic values.
-* Exercises:: Ideas for improving the multi-function calculator.
-
-Reverse Polish Notation Calculator
-
-* Decls: Rpcalc Decls. Bison and C declarations for rpcalc.
-* Rules: Rpcalc Rules. Grammar Rules for rpcalc, with explanation.
-* Lexer: Rpcalc Lexer. The lexical analyzer.
-* Main: Rpcalc Main. The controlling function.
-* Error: Rpcalc Error. The error reporting function.
-* Gen: Rpcalc Gen. Running Bison on the grammar file.
-* Comp: Rpcalc Compile. Run the C compiler on the output code.
-
-Grammar Rules for `rpcalc'
-
-* Rpcalc Input::
-* Rpcalc Line::
-* Rpcalc Expr::
-
-Multi-Function Calculator: `mfcalc'
-
-* Decl: Mfcalc Decl. Bison declarations for multi-function calculator.
-* Rules: Mfcalc Rules. Grammar rules for the calculator.
-* Symtab: Mfcalc Symtab. Symbol table management subroutines.
-
-Bison Grammar Files
-
-* Grammar Outline:: Overall layout of the grammar file.
-* Symbols:: Terminal and nonterminal symbols.
-* Rules:: How to write grammar rules.
-* Recursion:: Writing recursive rules.
-* Semantics:: Semantic values and actions.
-* Declarations:: All kinds of Bison declarations are described here.
-* Multiple Parsers:: Putting more than one Bison parser in one program.
-
-Outline of a Bison Grammar
-
-* C Declarations:: Syntax and usage of the C declarations section.
-* Bison Declarations:: Syntax and usage of the Bison declarations section.
-* Grammar Rules:: Syntax and usage of the grammar rules section.
-* C Code:: Syntax and usage of the additional C code section.
-
-Defining Language Semantics
-
-* Value Type:: Specifying one data type for all semantic values.
-* Multiple Types:: Specifying several alternative data types.
-* Actions:: An action is the semantic definition of a grammar rule.
-* Action Types:: Specifying data types for actions to operate on.
-* Mid-Rule Actions:: Most actions go at the end of a rule.
- This says when, why and how to use the exceptional
- action in the middle of a rule.
-
-Bison Declarations
-
-* Token Decl:: Declaring terminal symbols.
-* Precedence Decl:: Declaring terminals with precedence and associativity.
-* Union Decl:: Declaring the set of all semantic value types.
-* Type Decl:: Declaring the choice of type for a nonterminal symbol.
-* Expect Decl:: Suppressing warnings about shift/reduce conflicts.
-* Start Decl:: Specifying the start symbol.
-* Pure Decl:: Requesting a reentrant parser.
-* Decl Summary:: Table of all Bison declarations.
-
-Parser C-Language Interface
-
-* Parser Function:: How to call `yyparse' and what it returns.
-* Lexical:: You must supply a function `yylex'
- which reads tokens.
-* Error Reporting:: You must supply a function `yyerror'.
-* Action Features:: Special features for use in actions.
-
-The Lexical Analyzer Function `yylex'
-
-* Calling Convention:: How `yyparse' calls `yylex'.
-* Token Values:: How `yylex' must return the semantic value
- of the token it has read.
-* Token Positions:: How `yylex' must return the text position
- (line number, etc.) of the token, if the
- actions want that.
-* Pure Calling:: How the calling convention differs
- in a pure parser (*note A Pure (Reentrant) Parser: Pure Decl.).
-
-The Bison Parser Algorithm
-
-* Look-Ahead:: Parser looks one token ahead when deciding what to do.
-* Shift/Reduce:: Conflicts: when either shifting or reduction is valid.
-* Precedence:: Operator precedence works by resolving conflicts.
-* Contextual Precedence:: When an operator's precedence depends on context.
-* Parser States:: The parser is a finite-state-machine with stack.
-* Reduce/Reduce:: When two rules are applicable in the same situation.
-* Mystery Conflicts:: Reduce/reduce conflicts that look unjustified.
-* Stack Overflow:: What happens when stack gets full. How to avoid it.
-
-Operator Precedence
-
-* Why Precedence:: An example showing why precedence is needed.
-* Using Precedence:: How to specify precedence in Bison grammars.
-* Precedence Examples:: How these features are used in the previous example.
-* How Precedence:: How they work.
-
-Handling Context Dependencies
-
-* Semantic Tokens:: Token parsing can depend on the semantic context.
-* Lexical Tie-ins:: Token parsing can depend on the syntactic context.
-* Tie-in Recovery:: Lexical tie-ins have implications for how
- error recovery rules must be written.
-
-Invoking Bison
-
-* Bison Options:: All the options described in detail,
- in alphabetical order by short options.
-* Option Cross Key:: Alphabetical list of long options.
-* VMS Invocation:: Bison command syntax on VMS.
-
-
-File: bison.info, Node: Introduction, Next: Conditions, Prev: Top, Up: Top
-
-Introduction
-************
-
- "Bison" is a general-purpose parser generator that converts a
-grammar description for an LALR(1) context-free grammar into a C
-program to parse that grammar. Once you are proficient with Bison, you
-may use it to develop a wide range of language parsers, from those used
-in simple desk calculators to complex programming languages.
-
- Bison is upward compatible with Yacc: all properly-written Yacc
-grammars ought to work with Bison with no change. Anyone familiar with
-Yacc should be able to use Bison with little trouble. You need to be
-fluent in C programming in order to use Bison or to understand this
-manual.
-
- We begin with tutorial chapters that explain the basic concepts of
-using Bison and show three explained examples, each building on the
-last. If you don't know Bison or Yacc, start by reading these
-chapters. Reference chapters follow which describe specific aspects of
-Bison in detail.
-
- Bison was written primarily by Robert Corbett; Richard Stallman made
-it Yacc-compatible. Wilfred Hansen of Carnegie Mellon University added
-multicharacter string literals and other features.
-
- This edition corresponds to version 1.25 of Bison.
-
-
-File: bison.info, Node: Conditions, Next: Copying, Prev: Introduction, Up: Top
-
-Conditions for Using Bison
-**************************
-
- As of Bison version 1.24, we have changed the distribution terms for
-`yyparse' to permit using Bison's output in non-free programs.
-Formerly, Bison parsers could be used only in programs that were free
-software.
-
- The other GNU programming tools, such as the GNU C compiler, have
-never had such a requirement. They could always be used for non-free
-software. The reason Bison was different was not due to a special
-policy decision; it resulted from applying the usual General Public
-License to all of the Bison source code.
-
- The output of the Bison utility--the Bison parser file--contains a
-verbatim copy of a sizable piece of Bison, which is the code for the
-`yyparse' function. (The actions from your grammar are inserted into
-this function at one point, but the rest of the function is not
-changed.) When we applied the GPL terms to the code for `yyparse', the
-effect was to restrict the use of Bison output to free software.
-
- We didn't change the terms because of sympathy for people who want to
-make software proprietary. *Software should be free.* But we
-concluded that limiting Bison's use to free software was doing little to
-encourage people to make other software free. So we decided to make the
-practical conditions for using Bison match the practical conditions for
-using the other GNU tools.
-
-
-File: bison.info, Node: Copying, Next: Concepts, Prev: Conditions, Up: Top
-
-GNU GENERAL PUBLIC LICENSE
-**************************
-
- Version 2, June 1991
-
- Copyright (C) 1989, 1991 Free Software Foundation, Inc.
- 675 Mass Ave, Cambridge, MA 02139, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-Preamble
-========
-
- The licenses for most software are designed to take away your
-freedom to share and change it. By contrast, the GNU General Public
-License is intended to guarantee your freedom to share and change free
-software--to make sure the software is free for all its users. This
-General Public License applies to most of the Free Software
-Foundation's software and to any other program whose authors commit to
-using it. (Some other Free Software Foundation software is covered by
-the GNU Library General Public License instead.) You can apply it to
-your programs, too.
-
- When we speak of free software, we are referring to freedom, not
-price. Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-this service if you wish), that you receive source code or can get it
-if you want it, that you can change the software or use pieces of it in
-new free programs; and that you know you can do these things.
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-
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-and (2) offer you this license which gives you legal permission to copy,
-distribute and/or modify the software.
-
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-that everyone understands that there is no warranty for this free
-software. If the software is modified by someone else and passed on, we
-want its recipients to know that what they have is not the original, so
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-
- TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-
- 0. This License applies to any program or other work which contains a
- notice placed by the copyright holder saying it may be distributed
- under the terms of this General Public License. The "Program",
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- translated into another language. (Hereinafter, translation is
- included without limitation in the term "modification".) Each
- licensee is addressed as "you".
-
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- not covered by this License; they are outside its scope. The act
- of running the Program is not restricted, and the output from the
- Program is covered only if its contents constitute a work based on
- the Program (independent of having been made by running the
- Program). Whether that is true depends on what the Program does.
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- source code as you receive it, in any medium, provided that you
- conspicuously and appropriately publish on each copy an appropriate
- copyright notice and disclaimer of warranty; keep intact all the
- notices that refer to this License and to the absence of any
- warranty; and give any other recipients of the Program a copy of
- this License along with the Program.
-
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- distribute such modifications or work under the terms of Section 1
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-
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- stating that you changed the files and the date of any change.
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- in whole or in part contains or is derived from the Program
- or any part thereof, to be licensed as a whole at no charge
- to all third parties under the terms of this License.
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- when run, you must cause it, when started running for such
- interactive use in the most ordinary way, to print or display
- an announcement including an appropriate copyright notice and
- a notice that there is no warranty (or else, saying that you
- provide a warranty) and that users may redistribute the
- program under these conditions, and telling the user how to
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- announcement, your work based on the Program is not required
- to print an announcement.)
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- identifiable sections of that work are not derived from the
- Program, and can be reasonably considered independent and separate
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- apply to those sections when you distribute them as separate
- works. But when you distribute the same sections as part of a
- whole which is a work based on the Program, the distribution of
- the whole must be on the terms of this License, whose permissions
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- and every part regardless of who wrote it.
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- Program with the Program (or with a work based on the Program) on
- a volume of a storage or distribution medium does not bring the
- other work under the scope of this License.
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- under Section 2) in object code or executable form under the terms
- of Sections 1 and 2 above provided that you also do one of the
- following:
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- such an offer, in accord with Subsection b above.)
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- END OF TERMS AND CONDITIONS
-
-How to Apply These Terms to Your New Programs
-=============================================
-
- If you develop a new program, and you want it to be of the greatest
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- Copyright (C) 19YY NAME OF AUTHOR
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- The hypothetical commands `show w' and `show c' should show the
-appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than `show w' and `show
-c'; they could even be mouse-clicks or menu items--whatever suits your
-program.
-
- You should also get your employer (if you work as a programmer) or
-your school, if any, to sign a "copyright disclaimer" for the program,
-if necessary. Here is a sample; alter the names:
-
- Yoyodyne, Inc., hereby disclaims all copyright interest in the program
- `Gnomovision' (which makes passes at compilers) written by James Hacker.
-
- SIGNATURE OF TY COON, 1 April 1989
- Ty Coon, President of Vice
-
- This General Public License does not permit incorporating your
-program into proprietary programs. If your program is a subroutine
-library, you may consider it more useful to permit linking proprietary
-applications with the library. If this is what you want to do, use the
-GNU Library General Public License instead of this License.
-
-
-File: bison.info, Node: Concepts, Next: Examples, Prev: Copying, Up: Top
-
-The Concepts of Bison
-*********************
-
- This chapter introduces many of the basic concepts without which the
-details of Bison will not make sense. If you do not already know how to
-use Bison or Yacc, we suggest you start by reading this chapter
-carefully.
-
-* Menu:
-
-* Language and Grammar:: Languages and context-free grammars,
- as mathematical ideas.
-* Grammar in Bison:: How we represent grammars for Bison's sake.
-* Semantic Values:: Each token or syntactic grouping can have
- a semantic value (the value of an integer,
- the name of an identifier, etc.).
-* Semantic Actions:: Each rule can have an action containing C code.
-* Bison Parser:: What are Bison's input and output,
- how is the output used?
-* Stages:: Stages in writing and running Bison grammars.
-* Grammar Layout:: Overall structure of a Bison grammar file.
-
-
-File: bison.info, Node: Language and Grammar, Next: Grammar in Bison, Up: Concepts
-
-Languages and Context-Free Grammars
-===================================
-
- In order for Bison to parse a language, it must be described by a
-"context-free grammar". This means that you specify one or more
-"syntactic groupings" and give rules for constructing them from their
-parts. For example, in the C language, one kind of grouping is called
-an `expression'. One rule for making an expression might be, "An
-expression can be made of a minus sign and another expression".
-Another would be, "An expression can be an integer". As you can see,
-rules are often recursive, but there must be at least one rule which
-leads out of the recursion.
-
- The most common formal system for presenting such rules for humans
-to read is "Backus-Naur Form" or "BNF", which was developed in order to
-specify the language Algol 60. Any grammar expressed in BNF is a
-context-free grammar. The input to Bison is essentially
-machine-readable BNF.
-
- Not all context-free languages can be handled by Bison, only those
-that are LALR(1). In brief, this means that it must be possible to
-tell how to parse any portion of an input string with just a single
-token of look-ahead. Strictly speaking, that is a description of an
-LR(1) grammar, and LALR(1) involves additional restrictions that are
-hard to explain simply; but it is rare in actual practice to find an
-LR(1) grammar that fails to be LALR(1). *Note Mysterious Reduce/Reduce
-Conflicts: Mystery Conflicts, for more information on this.
-
- In the formal grammatical rules for a language, each kind of
-syntactic unit or grouping is named by a "symbol". Those which are
-built by grouping smaller constructs according to grammatical rules are
-called "nonterminal symbols"; those which can't be subdivided are called
-"terminal symbols" or "token types". We call a piece of input
-corresponding to a single terminal symbol a "token", and a piece
-corresponding to a single nonterminal symbol a "grouping".
-
- We can use the C language as an example of what symbols, terminal and
-nonterminal, mean. The tokens of C are identifiers, constants (numeric
-and string), and the various keywords, arithmetic operators and
-punctuation marks. So the terminal symbols of a grammar for C include
-`identifier', `number', `string', plus one symbol for each keyword,
-operator or punctuation mark: `if', `return', `const', `static', `int',
-`char', `plus-sign', `open-brace', `close-brace', `comma' and many
-more. (These tokens can be subdivided into characters, but that is a
-matter of lexicography, not grammar.)
-
- Here is a simple C function subdivided into tokens:
-
- int /* keyword `int' */
- square (x) /* identifier, open-paren, */
- /* identifier, close-paren */
- int x; /* keyword `int', identifier, semicolon */
- { /* open-brace */
- return x * x; /* keyword `return', identifier, */
- /* asterisk, identifier, semicolon */
- } /* close-brace */
-
- The syntactic groupings of C include the expression, the statement,
-the declaration, and the function definition. These are represented in
-the grammar of C by nonterminal symbols `expression', `statement',
-`declaration' and `function definition'. The full grammar uses dozens
-of additional language constructs, each with its own nonterminal
-symbol, in order to express the meanings of these four. The example
-above is a function definition; it contains one declaration, and one
-statement. In the statement, each `x' is an expression and so is `x *
-x'.
-
- Each nonterminal symbol must have grammatical rules showing how it
-is made out of simpler constructs. For example, one kind of C
-statement is the `return' statement; this would be described with a
-grammar rule which reads informally as follows:
-
- A `statement' can be made of a `return' keyword, an `expression'
- and a `semicolon'.
-
-There would be many other rules for `statement', one for each kind of
-statement in C.
-
- One nonterminal symbol must be distinguished as the special one which
-defines a complete utterance in the language. It is called the "start
-symbol". In a compiler, this means a complete input program. In the C
-language, the nonterminal symbol `sequence of definitions and
-declarations' plays this role.
-
- For example, `1 + 2' is a valid C expression--a valid part of a C
-program--but it is not valid as an *entire* C program. In the
-context-free grammar of C, this follows from the fact that `expression'
-is not the start symbol.
-
- The Bison parser reads a sequence of tokens as its input, and groups
-the tokens using the grammar rules. If the input is valid, the end
-result is that the entire token sequence reduces to a single grouping
-whose symbol is the grammar's start symbol. If we use a grammar for C,
-the entire input must be a `sequence of definitions and declarations'.
-If not, the parser reports a syntax error.
-
-
-File: bison.info, Node: Grammar in Bison, Next: Semantic Values, Prev: Language and Grammar, Up: Concepts
-
-From Formal Rules to Bison Input
-================================
-
- A formal grammar is a mathematical construct. To define the language
-for Bison, you must write a file expressing the grammar in Bison syntax:
-a "Bison grammar" file. *Note Bison Grammar Files: Grammar File.
-
- A nonterminal symbol in the formal grammar is represented in Bison
-input as an identifier, like an identifier in C. By convention, it
-should be in lower case, such as `expr', `stmt' or `declaration'.
-
- The Bison representation for a terminal symbol is also called a
-"token type". Token types as well can be represented as C-like
-identifiers. By convention, these identifiers should be upper case to
-distinguish them from nonterminals: for example, `INTEGER',
-`IDENTIFIER', `IF' or `RETURN'. A terminal symbol that stands for a
-particular keyword in the language should be named after that keyword
-converted to upper case. The terminal symbol `error' is reserved for
-error recovery. *Note Symbols::.
-
- A terminal symbol can also be represented as a character literal,
-just like a C character constant. You should do this whenever a token
-is just a single character (parenthesis, plus-sign, etc.): use that
-same character in a literal as the terminal symbol for that token.
-
- A third way to represent a terminal symbol is with a C string
-constant containing several characters. *Note Symbols::, for more
-information.
-
- The grammar rules also have an expression in Bison syntax. For
-example, here is the Bison rule for a C `return' statement. The
-semicolon in quotes is a literal character token, representing part of
-the C syntax for the statement; the naked semicolon, and the colon, are
-Bison punctuation used in every rule.
-
- stmt: RETURN expr ';'
- ;
-
-*Note Syntax of Grammar Rules: Rules.
-
-
-File: bison.info, Node: Semantic Values, Next: Semantic Actions, Prev: Grammar in Bison, Up: Concepts
-
-Semantic Values
-===============
-
- A formal grammar selects tokens only by their classifications: for
-example, if a rule mentions the terminal symbol `integer constant', it
-means that *any* integer constant is grammatically valid in that
-position. The precise value of the constant is irrelevant to how to
-parse the input: if `x+4' is grammatical then `x+1' or `x+3989' is
-equally grammatical.
-
- But the precise value is very important for what the input means
-once it is parsed. A compiler is useless if it fails to distinguish
-between 4, 1 and 3989 as constants in the program! Therefore, each
-token in a Bison grammar has both a token type and a "semantic value".
-*Note Defining Language Semantics: Semantics, for details.
-
- The token type is a terminal symbol defined in the grammar, such as
-`INTEGER', `IDENTIFIER' or `',''. It tells everything you need to know
-to decide where the token may validly appear and how to group it with
-other tokens. The grammar rules know nothing about tokens except their
-types.
-
- The semantic value has all the rest of the information about the
-meaning of the token, such as the value of an integer, or the name of an
-identifier. (A token such as `','' which is just punctuation doesn't
-need to have any semantic value.)
-
- For example, an input token might be classified as token type
-`INTEGER' and have the semantic value 4. Another input token might
-have the same token type `INTEGER' but value 3989. When a grammar rule
-says that `INTEGER' is allowed, either of these tokens is acceptable
-because each is an `INTEGER'. When the parser accepts the token, it
-keeps track of the token's semantic value.
-
- Each grouping can also have a semantic value as well as its
-nonterminal symbol. For example, in a calculator, an expression
-typically has a semantic value that is a number. In a compiler for a
-programming language, an expression typically has a semantic value that
-is a tree structure describing the meaning of the expression.
-
-
-File: bison.info, Node: Semantic Actions, Next: Bison Parser, Prev: Semantic Values, Up: Concepts
-
-Semantic Actions
-================
-
- In order to be useful, a program must do more than parse input; it
-must also produce some output based on the input. In a Bison grammar,
-a grammar rule can have an "action" made up of C statements. Each time
-the parser recognizes a match for that rule, the action is executed.
-*Note Actions::.
-
- Most of the time, the purpose of an action is to compute the
-semantic value of the whole construct from the semantic values of its
-parts. For example, suppose we have a rule which says an expression
-can be the sum of two expressions. When the parser recognizes such a
-sum, each of the subexpressions has a semantic value which describes
-how it was built up. The action for this rule should create a similar
-sort of value for the newly recognized larger expression.
-
- For example, here is a rule that says an expression can be the sum of
-two subexpressions:
-
- expr: expr '+' expr { $$ = $1 + $3; }
- ;
-
-The action says how to produce the semantic value of the sum expression
-from the values of the two subexpressions.
-
-
-File: bison.info, Node: Bison Parser, Next: Stages, Prev: Semantic Actions, Up: Concepts
-
-Bison Output: the Parser File
-=============================
-
- When you run Bison, you give it a Bison grammar file as input. The
-output is a C source file that parses the language described by the
-grammar. This file is called a "Bison parser". Keep in mind that the
-Bison utility and the Bison parser are two distinct programs: the Bison
-utility is a program whose output is the Bison parser that becomes part
-of your program.
-
- The job of the Bison parser is to group tokens into groupings
-according to the grammar rules--for example, to build identifiers and
-operators into expressions. As it does this, it runs the actions for
-the grammar rules it uses.
-
- The tokens come from a function called the "lexical analyzer" that
-you must supply in some fashion (such as by writing it in C). The
-Bison parser calls the lexical analyzer each time it wants a new token.
-It doesn't know what is "inside" the tokens (though their semantic
-values may reflect this). Typically the lexical analyzer makes the
-tokens by parsing characters of text, but Bison does not depend on
-this. *Note The Lexical Analyzer Function `yylex': Lexical.
-
- The Bison parser file is C code which defines a function named
-`yyparse' which implements that grammar. This function does not make a
-complete C program: you must supply some additional functions. One is
-the lexical analyzer. Another is an error-reporting function which the
-parser calls to report an error. In addition, a complete C program must
-start with a function called `main'; you have to provide this, and
-arrange for it to call `yyparse' or the parser will never run. *Note
-Parser C-Language Interface: Interface.
-
- Aside from the token type names and the symbols in the actions you
-write, all variable and function names used in the Bison parser file
-begin with `yy' or `YY'. This includes interface functions such as the
-lexical analyzer function `yylex', the error reporting function
-`yyerror' and the parser function `yyparse' itself. This also includes
-numerous identifiers used for internal purposes. Therefore, you should
-avoid using C identifiers starting with `yy' or `YY' in the Bison
-grammar file except for the ones defined in this manual.
-
-
-File: bison.info, Node: Stages, Next: Grammar Layout, Prev: Bison Parser, Up: Concepts
-
-Stages in Using Bison
-=====================
-
- The actual language-design process using Bison, from grammar
-specification to a working compiler or interpreter, has these parts:
-
- 1. Formally specify the grammar in a form recognized by Bison (*note
- Bison Grammar Files: Grammar File.). For each grammatical rule in
- the language, describe the action that is to be taken when an
- instance of that rule is recognized. The action is described by a
- sequence of C statements.
-
- 2. Write a lexical analyzer to process input and pass tokens to the
- parser. The lexical analyzer may be written by hand in C (*note
- The Lexical Analyzer Function `yylex': Lexical.). It could also
- be produced using Lex, but the use of Lex is not discussed in this
- manual.
-
- 3. Write a controlling function that calls the Bison-produced parser.
-
- 4. Write error-reporting routines.
-
- To turn this source code as written into a runnable program, you
-must follow these steps:
-
- 1. Run Bison on the grammar to produce the parser.
-
- 2. Compile the code output by Bison, as well as any other source
- files.
-
- 3. Link the object files to produce the finished product.
-
-
-File: bison.info, Node: Grammar Layout, Prev: Stages, Up: Concepts
-
-The Overall Layout of a Bison Grammar
-=====================================
-
- The input file for the Bison utility is a "Bison grammar file". The
-general form of a Bison grammar file is as follows:
-
- %{
- C DECLARATIONS
- %}
-
- BISON DECLARATIONS
-
- %%
- GRAMMAR RULES
- %%
- ADDITIONAL C CODE
-
-The `%%', `%{' and `%}' are punctuation that appears in every Bison
-grammar file to separate the sections.
-
- The C declarations may define types and variables used in the
-actions. You can also use preprocessor commands to define macros used
-there, and use `#include' to include header files that do any of these
-things.
-
- The Bison declarations declare the names of the terminal and
-nonterminal symbols, and may also describe operator precedence and the
-data types of semantic values of various symbols.
-
- The grammar rules define how to construct each nonterminal symbol
-from its parts.
-
- The additional C code can contain any C code you want to use. Often
-the definition of the lexical analyzer `yylex' goes here, plus
-subroutines called by the actions in the grammar rules. In a simple
-program, all the rest of the program can go here.
-
-
-File: bison.info, Node: Examples, Next: Grammar File, Prev: Concepts, Up: Top
-
-Examples
-********
-
- Now we show and explain three sample programs written using Bison: a
-reverse polish notation calculator, an algebraic (infix) notation
-calculator, and a multi-function calculator. All three have been tested
-under BSD Unix 4.3; each produces a usable, though limited, interactive
-desk-top calculator.
-
- These examples are simple, but Bison grammars for real programming
-languages are written the same way. You can copy these examples out of
-the Info file and into a source file to try them.
-
-* Menu:
-
-* RPN Calc:: Reverse polish notation calculator;
- a first example with no operator precedence.
-* Infix Calc:: Infix (algebraic) notation calculator.
- Operator precedence is introduced.
-* Simple Error Recovery:: Continuing after syntax errors.
-* Multi-function Calc:: Calculator with memory and trig functions.
- It uses multiple data-types for semantic values.
-* Exercises:: Ideas for improving the multi-function calculator.
-
-
-File: bison.info, Node: RPN Calc, Next: Infix Calc, Up: Examples
-
-Reverse Polish Notation Calculator
-==================================
-
- The first example is that of a simple double-precision "reverse
-polish notation" calculator (a calculator using postfix operators).
-This example provides a good starting point, since operator precedence
-is not an issue. The second example will illustrate how operator
-precedence is handled.
-
- The source code for this calculator is named `rpcalc.y'. The `.y'
-extension is a convention used for Bison input files.
-
-* Menu:
-
-* Decls: Rpcalc Decls. Bison and C declarations for rpcalc.
-* Rules: Rpcalc Rules. Grammar Rules for rpcalc, with explanation.
-* Lexer: Rpcalc Lexer. The lexical analyzer.
-* Main: Rpcalc Main. The controlling function.
-* Error: Rpcalc Error. The error reporting function.
-* Gen: Rpcalc Gen. Running Bison on the grammar file.
-* Comp: Rpcalc Compile. Run the C compiler on the output code.
-
-
-File: bison.info, Node: Rpcalc Decls, Next: Rpcalc Rules, Up: RPN Calc
-
-Declarations for `rpcalc'
--------------------------
-
- Here are the C and Bison declarations for the reverse polish notation
-calculator. As in C, comments are placed between `/*...*/'.
-
- /* Reverse polish notation calculator. */
-
- %{
- #define YYSTYPE double
- #include <math.h>
- %}
-
- %token NUM
-
- %% /* Grammar rules and actions follow */
-
- The C declarations section (*note The C Declarations Section: C
-Declarations.) contains two preprocessor directives.
-
- The `#define' directive defines the macro `YYSTYPE', thus specifying
-the C data type for semantic values of both tokens and groupings (*note
-Data Types of Semantic Values: Value Type.). The Bison parser will use
-whatever type `YYSTYPE' is defined as; if you don't define it, `int' is
-the default. Because we specify `double', each token and each
-expression has an associated value, which is a floating point number.
-
- The `#include' directive is used to declare the exponentiation
-function `pow'.
-
- The second section, Bison declarations, provides information to
-Bison about the token types (*note The Bison Declarations Section:
-Bison Declarations.). Each terminal symbol that is not a
-single-character literal must be declared here. (Single-character
-literals normally don't need to be declared.) In this example, all the
-arithmetic operators are designated by single-character literals, so the
-only terminal symbol that needs to be declared is `NUM', the token type
-for numeric constants.
-
diff -rup --new-file baseline/fsf/bison/bison.info-2 amiga/fsf/bison/bison.info-2
--- baseline/fsf/bison/bison.info-2 Sat Feb 17 09:46:06 1996
+++ amiga/fsf/bison/bison.info-2 Wed Dec 31 17:00:00 1969
@@ -1,1333 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-File: bison.info, Node: Rpcalc Rules, Next: Rpcalc Lexer, Prev: Rpcalc Decls, Up: RPN Calc
-
-Grammar Rules for `rpcalc'
---------------------------
-
- Here are the grammar rules for the reverse polish notation
-calculator.
-
- input: /* empty */
- | input line
- ;
-
- line: '\n'
- | exp '\n' { printf ("\t%.10g\n", $1); }
- ;
-
- exp: NUM { $$ = $1; }
- | exp exp '+' { $$ = $1 + $2; }
- | exp exp '-' { $$ = $1 - $2; }
- | exp exp '*' { $$ = $1 * $2; }
- | exp exp '/' { $$ = $1 / $2; }
- /* Exponentiation */
- | exp exp '^' { $$ = pow ($1, $2); }
- /* Unary minus */
- | exp 'n' { $$ = -$1; }
- ;
- %%
-
- The groupings of the rpcalc "language" defined here are the
-expression (given the name `exp'), the line of input (`line'), and the
-complete input transcript (`input'). Each of these nonterminal symbols
-has several alternate rules, joined by the `|' punctuator which is read
-as "or". The following sections explain what these rules mean.
-
- The semantics of the language is determined by the actions taken
-when a grouping is recognized. The actions are the C code that appears
-inside braces. *Note Actions::.
-
- You must specify these actions in C, but Bison provides the means for
-passing semantic values between the rules. In each action, the
-pseudo-variable `$$' stands for the semantic value for the grouping
-that the rule is going to construct. Assigning a value to `$$' is the
-main job of most actions. The semantic values of the components of the
-rule are referred to as `$1', `$2', and so on.
-
-* Menu:
-
-* Rpcalc Input::
-* Rpcalc Line::
-* Rpcalc Expr::
-
-
-File: bison.info, Node: Rpcalc Input, Next: Rpcalc Line, Up: Rpcalc Rules
-
-Explanation of `input'
-......................
-
- Consider the definition of `input':
-
- input: /* empty */
- | input line
- ;
-
- This definition reads as follows: "A complete input is either an
-empty string, or a complete input followed by an input line". Notice
-that "complete input" is defined in terms of itself. This definition
-is said to be "left recursive" since `input' appears always as the
-leftmost symbol in the sequence. *Note Recursive Rules: Recursion.
-
- The first alternative is empty because there are no symbols between
-the colon and the first `|'; this means that `input' can match an empty
-string of input (no tokens). We write the rules this way because it is
-legitimate to type `Ctrl-d' right after you start the calculator. It's
-conventional to put an empty alternative first and write the comment
-`/* empty */' in it.
-
- The second alternate rule (`input line') handles all nontrivial
-input. It means, "After reading any number of lines, read one more
-line if possible." The left recursion makes this rule into a loop.
-Since the first alternative matches empty input, the loop can be
-executed zero or more times.
-
- The parser function `yyparse' continues to process input until a
-grammatical error is seen or the lexical analyzer says there are no more
-input tokens; we will arrange for the latter to happen at end of file.
-
-
-File: bison.info, Node: Rpcalc Line, Next: Rpcalc Expr, Prev: Rpcalc Input, Up: Rpcalc Rules
-
-Explanation of `line'
-.....................
-
- Now consider the definition of `line':
-
- line: '\n'
- | exp '\n' { printf ("\t%.10g\n", $1); }
- ;
-
- The first alternative is a token which is a newline character; this
-means that rpcalc accepts a blank line (and ignores it, since there is
-no action). The second alternative is an expression followed by a
-newline. This is the alternative that makes rpcalc useful. The
-semantic value of the `exp' grouping is the value of `$1' because the
-`exp' in question is the first symbol in the alternative. The action
-prints this value, which is the result of the computation the user
-asked for.
-
- This action is unusual because it does not assign a value to `$$'.
-As a consequence, the semantic value associated with the `line' is
-uninitialized (its value will be unpredictable). This would be a bug if
-that value were ever used, but we don't use it: once rpcalc has printed
-the value of the user's input line, that value is no longer needed.
-
-
-File: bison.info, Node: Rpcalc Expr, Prev: Rpcalc Line, Up: Rpcalc Rules
-
-Explanation of `expr'
-.....................
-
- The `exp' grouping has several rules, one for each kind of
-expression. The first rule handles the simplest expressions: those
-that are just numbers. The second handles an addition-expression,
-which looks like two expressions followed by a plus-sign. The third
-handles subtraction, and so on.
-
- exp: NUM
- | exp exp '+' { $$ = $1 + $2; }
- | exp exp '-' { $$ = $1 - $2; }
- ...
- ;
-
- We have used `|' to join all the rules for `exp', but we could
-equally well have written them separately:
-
- exp: NUM ;
- exp: exp exp '+' { $$ = $1 + $2; } ;
- exp: exp exp '-' { $$ = $1 - $2; } ;
- ...
-
- Most of the rules have actions that compute the value of the
-expression in terms of the value of its parts. For example, in the
-rule for addition, `$1' refers to the first component `exp' and `$2'
-refers to the second one. The third component, `'+'', has no meaningful
-associated semantic value, but if it had one you could refer to it as
-`$3'. When `yyparse' recognizes a sum expression using this rule, the
-sum of the two subexpressions' values is produced as the value of the
-entire expression. *Note Actions::.
-
- You don't have to give an action for every rule. When a rule has no
-action, Bison by default copies the value of `$1' into `$$'. This is
-what happens in the first rule (the one that uses `NUM').
-
- The formatting shown here is the recommended convention, but Bison
-does not require it. You can add or change whitespace as much as you
-wish. For example, this:
-
- exp : NUM | exp exp '+' {$$ = $1 + $2; } | ...
-
-means the same thing as this:
-
- exp: NUM
- | exp exp '+' { $$ = $1 + $2; }
- | ...
-
-The latter, however, is much more readable.
-
-
-File: bison.info, Node: Rpcalc Lexer, Next: Rpcalc Main, Prev: Rpcalc Rules, Up: RPN Calc
-
-The `rpcalc' Lexical Analyzer
------------------------------
-
- The lexical analyzer's job is low-level parsing: converting
-characters or sequences of characters into tokens. The Bison parser
-gets its tokens by calling the lexical analyzer. *Note The Lexical
-Analyzer Function `yylex': Lexical.
-
- Only a simple lexical analyzer is needed for the RPN calculator.
-This lexical analyzer skips blanks and tabs, then reads in numbers as
-`double' and returns them as `NUM' tokens. Any other character that
-isn't part of a number is a separate token. Note that the token-code
-for such a single-character token is the character itself.
-
- The return value of the lexical analyzer function is a numeric code
-which represents a token type. The same text used in Bison rules to
-stand for this token type is also a C expression for the numeric code
-for the type. This works in two ways. If the token type is a
-character literal, then its numeric code is the ASCII code for that
-character; you can use the same character literal in the lexical
-analyzer to express the number. If the token type is an identifier,
-that identifier is defined by Bison as a C macro whose definition is
-the appropriate number. In this example, therefore, `NUM' becomes a
-macro for `yylex' to use.
-
- The semantic value of the token (if it has one) is stored into the
-global variable `yylval', which is where the Bison parser will look for
-it. (The C data type of `yylval' is `YYSTYPE', which was defined at
-the beginning of the grammar; *note Declarations for `rpcalc': Rpcalc
-Decls..)
-
- A token type code of zero is returned if the end-of-file is
-encountered. (Bison recognizes any nonpositive value as indicating the
-end of the input.)
-
- Here is the code for the lexical analyzer:
-
- /* Lexical analyzer returns a double floating point
- number on the stack and the token NUM, or the ASCII
- character read if not a number. Skips all blanks
- and tabs, returns 0 for EOF. */
-
- #include <ctype.h>
-
- yylex ()
- {
- int c;
-
- /* skip white space */
- while ((c = getchar ()) == ' ' || c == '\t')
- ;
- /* process numbers */
- if (c == '.' || isdigit (c))
- {
- ungetc (c, stdin);
- scanf ("%lf", &yylval);
- return NUM;
- }
- /* return end-of-file */
- if (c == EOF)
- return 0;
- /* return single chars */
- return c;
- }
-
-
-File: bison.info, Node: Rpcalc Main, Next: Rpcalc Error, Prev: Rpcalc Lexer, Up: RPN Calc
-
-The Controlling Function
-------------------------
-
- In keeping with the spirit of this example, the controlling function
-is kept to the bare minimum. The only requirement is that it call
-`yyparse' to start the process of parsing.
-
- main ()
- {
- yyparse ();
- }
-
-
-File: bison.info, Node: Rpcalc Error, Next: Rpcalc Gen, Prev: Rpcalc Main, Up: RPN Calc
-
-The Error Reporting Routine
----------------------------
-
- When `yyparse' detects a syntax error, it calls the error reporting
-function `yyerror' to print an error message (usually but not always
-`"parse error"'). It is up to the programmer to supply `yyerror'
-(*note Parser C-Language Interface: Interface.), so here is the
-definition we will use:
-
- #include <stdio.h>
-
- yyerror (s) /* Called by yyparse on error */
- char *s;
- {
- printf ("%s\n", s);
- }
-
- After `yyerror' returns, the Bison parser may recover from the error
-and continue parsing if the grammar contains a suitable error rule
-(*note Error Recovery::.). Otherwise, `yyparse' returns nonzero. We
-have not written any error rules in this example, so any invalid input
-will cause the calculator program to exit. This is not clean behavior
-for a real calculator, but it is adequate in the first example.
-
-
-File: bison.info, Node: Rpcalc Gen, Next: Rpcalc Compile, Prev: Rpcalc Error, Up: RPN Calc
-
-Running Bison to Make the Parser
---------------------------------
-
- Before running Bison to produce a parser, we need to decide how to
-arrange all the source code in one or more source files. For such a
-simple example, the easiest thing is to put everything in one file.
-The definitions of `yylex', `yyerror' and `main' go at the end, in the
-"additional C code" section of the file (*note The Overall Layout of a
-Bison Grammar: Grammar Layout.).
-
- For a large project, you would probably have several source files,
-and use `make' to arrange to recompile them.
-
- With all the source in a single file, you use the following command
-to convert it into a parser file:
-
- bison FILE_NAME.y
-
-In this example the file was called `rpcalc.y' (for "Reverse Polish
-CALCulator"). Bison produces a file named `FILE_NAME.tab.c', removing
-the `.y' from the original file name. The file output by Bison contains
-the source code for `yyparse'. The additional functions in the input
-file (`yylex', `yyerror' and `main') are copied verbatim to the output.
-
-
-File: bison.info, Node: Rpcalc Compile, Prev: Rpcalc Gen, Up: RPN Calc
-
-Compiling the Parser File
--------------------------
-
- Here is how to compile and run the parser file:
-
- # List files in current directory.
- % ls
- rpcalc.tab.c rpcalc.y
-
- # Compile the Bison parser.
- # `-lm' tells compiler to search math library for `pow'.
- % cc rpcalc.tab.c -lm -o rpcalc
-
- # List files again.
- % ls
- rpcalc rpcalc.tab.c rpcalc.y
-
- The file `rpcalc' now contains the executable code. Here is an
-example session using `rpcalc'.
-
- % rpcalc
- 4 9 +
- 13
- 3 7 + 3 4 5 *+-
- -13
- 3 7 + 3 4 5 * + - n Note the unary minus, `n'
- 13
- 5 6 / 4 n +
- -3.166666667
- 3 4 ^ Exponentiation
- 81
- ^D End-of-file indicator
- %
-
-
-File: bison.info, Node: Infix Calc, Next: Simple Error Recovery, Prev: RPN Calc, Up: Examples
-
-Infix Notation Calculator: `calc'
-=================================
-
- We now modify rpcalc to handle infix operators instead of postfix.
-Infix notation involves the concept of operator precedence and the need
-for parentheses nested to arbitrary depth. Here is the Bison code for
-`calc.y', an infix desk-top calculator.
-
- /* Infix notation calculator--calc */
-
- %{
- #define YYSTYPE double
- #include <math.h>
- %}
-
- /* BISON Declarations */
- %token NUM
- %left '-' '+'
- %left '*' '/'
- %left NEG /* negation--unary minus */
- %right '^' /* exponentiation */
-
- /* Grammar follows */
- %%
- input: /* empty string */
- | input line
- ;
-
- line: '\n'
- | exp '\n' { printf ("\t%.10g\n", $1); }
- ;
-
- exp: NUM { $$ = $1; }
- | exp '+' exp { $$ = $1 + $3; }
- | exp '-' exp { $$ = $1 - $3; }
- | exp '*' exp { $$ = $1 * $3; }
- | exp '/' exp { $$ = $1 / $3; }
- | '-' exp %prec NEG { $$ = -$2; }
- | exp '^' exp { $$ = pow ($1, $3); }
- | '(' exp ')' { $$ = $2; }
- ;
- %%
-
-The functions `yylex', `yyerror' and `main' can be the same as before.
-
- There are two important new features shown in this code.
-
- In the second section (Bison declarations), `%left' declares token
-types and says they are left-associative operators. The declarations
-`%left' and `%right' (right associativity) take the place of `%token'
-which is used to declare a token type name without associativity.
-(These tokens are single-character literals, which ordinarily don't
-need to be declared. We declare them here to specify the
-associativity.)
-
- Operator precedence is determined by the line ordering of the
-declarations; the higher the line number of the declaration (lower on
-the page or screen), the higher the precedence. Hence, exponentiation
-has the highest precedence, unary minus (`NEG') is next, followed by
-`*' and `/', and so on. *Note Operator Precedence: Precedence.
-
- The other important new feature is the `%prec' in the grammar section
-for the unary minus operator. The `%prec' simply instructs Bison that
-the rule `| '-' exp' has the same precedence as `NEG'--in this case the
-next-to-highest. *Note Context-Dependent Precedence: Contextual
-Precedence.
-
- Here is a sample run of `calc.y':
-
- % calc
- 4 + 4.5 - (34/(8*3+-3))
- 6.880952381
- -56 + 2
- -54
- 3 ^ 2
- 9
-
-
-File: bison.info, Node: Simple Error Recovery, Next: Multi-function Calc, Prev: Infix Calc, Up: Examples
-
-Simple Error Recovery
-=====================
-
- Up to this point, this manual has not addressed the issue of "error
-recovery"--how to continue parsing after the parser detects a syntax
-error. All we have handled is error reporting with `yyerror'. Recall
-that by default `yyparse' returns after calling `yyerror'. This means
-that an erroneous input line causes the calculator program to exit.
-Now we show how to rectify this deficiency.
-
- The Bison language itself includes the reserved word `error', which
-may be included in the grammar rules. In the example below it has been
-added to one of the alternatives for `line':
-
- line: '\n'
- | exp '\n' { printf ("\t%.10g\n", $1); }
- | error '\n' { yyerrok; }
- ;
-
- This addition to the grammar allows for simple error recovery in the
-event of a parse error. If an expression that cannot be evaluated is
-read, the error will be recognized by the third rule for `line', and
-parsing will continue. (The `yyerror' function is still called upon to
-print its message as well.) The action executes the statement
-`yyerrok', a macro defined automatically by Bison; its meaning is that
-error recovery is complete (*note Error Recovery::.). Note the
-difference between `yyerrok' and `yyerror'; neither one is a misprint.
-
- This form of error recovery deals with syntax errors. There are
-other kinds of errors; for example, division by zero, which raises an
-exception signal that is normally fatal. A real calculator program
-must handle this signal and use `longjmp' to return to `main' and
-resume parsing input lines; it would also have to discard the rest of
-the current line of input. We won't discuss this issue further because
-it is not specific to Bison programs.
-
-
-File: bison.info, Node: Multi-function Calc, Next: Exercises, Prev: Simple Error Recovery, Up: Examples
-
-Multi-Function Calculator: `mfcalc'
-===================================
-
- Now that the basics of Bison have been discussed, it is time to move
-on to a more advanced problem. The above calculators provided only five
-functions, `+', `-', `*', `/' and `^'. It would be nice to have a
-calculator that provides other mathematical functions such as `sin',
-`cos', etc.
-
- It is easy to add new operators to the infix calculator as long as
-they are only single-character literals. The lexical analyzer `yylex'
-passes back all non-number characters as tokens, so new grammar rules
-suffice for adding a new operator. But we want something more
-flexible: built-in functions whose syntax has this form:
-
- FUNCTION_NAME (ARGUMENT)
-
-At the same time, we will add memory to the calculator, by allowing you
-to create named variables, store values in them, and use them later.
-Here is a sample session with the multi-function calculator:
-
- % mfcalc
- pi = 3.141592653589
- 3.1415926536
- sin(pi)
- 0.0000000000
- alpha = beta1 = 2.3
- 2.3000000000
- alpha
- 2.3000000000
- ln(alpha)
- 0.8329091229
- exp(ln(beta1))
- 2.3000000000
- %
-
- Note that multiple assignment and nested function calls are
-permitted.
-
-* Menu:
-
-* Decl: Mfcalc Decl. Bison declarations for multi-function calculator.
-* Rules: Mfcalc Rules. Grammar rules for the calculator.
-* Symtab: Mfcalc Symtab. Symbol table management subroutines.
-
-
-File: bison.info, Node: Mfcalc Decl, Next: Mfcalc Rules, Up: Multi-function Calc
-
-Declarations for `mfcalc'
--------------------------
-
- Here are the C and Bison declarations for the multi-function
-calculator.
-
- %{
- #include <math.h> /* For math functions, cos(), sin(), etc. */
- #include "calc.h" /* Contains definition of `symrec' */
- %}
- %union {
- double val; /* For returning numbers. */
- symrec *tptr; /* For returning symbol-table pointers */
- }
-
- %token <val> NUM /* Simple double precision number */
- %token <tptr> VAR FNCT /* Variable and Function */
- %type <val> exp
-
- %right '='
- %left '-' '+'
- %left '*' '/'
- %left NEG /* Negation--unary minus */
- %right '^' /* Exponentiation */
-
- /* Grammar follows */
-
- %%
-
- The above grammar introduces only two new features of the Bison
-language. These features allow semantic values to have various data
-types (*note More Than One Value Type: Multiple Types.).
-
- The `%union' declaration specifies the entire list of possible types;
-this is instead of defining `YYSTYPE'. The allowable types are now
-double-floats (for `exp' and `NUM') and pointers to entries in the
-symbol table. *Note The Collection of Value Types: Union Decl.
-
- Since values can now have various types, it is necessary to
-associate a type with each grammar symbol whose semantic value is used.
-These symbols are `NUM', `VAR', `FNCT', and `exp'. Their declarations
-are augmented with information about their data type (placed between
-angle brackets).
-
- The Bison construct `%type' is used for declaring nonterminal
-symbols, just as `%token' is used for declaring token types. We have
-not used `%type' before because nonterminal symbols are normally
-declared implicitly by the rules that define them. But `exp' must be
-declared explicitly so we can specify its value type. *Note
-Nonterminal Symbols: Type Decl.
-
-
-File: bison.info, Node: Mfcalc Rules, Next: Mfcalc Symtab, Prev: Mfcalc Decl, Up: Multi-function Calc
-
-Grammar Rules for `mfcalc'
---------------------------
-
- Here are the grammar rules for the multi-function calculator. Most
-of them are copied directly from `calc'; three rules, those which
-mention `VAR' or `FNCT', are new.
-
- input: /* empty */
- | input line
- ;
-
- line:
- '\n'
- | exp '\n' { printf ("\t%.10g\n", $1); }
- | error '\n' { yyerrok; }
- ;
-
- exp: NUM { $$ = $1; }
- | VAR { $$ = $1->value.var; }
- | VAR '=' exp { $$ = $3; $1->value.var = $3; }
- | FNCT '(' exp ')' { $$ = (*($1->value.fnctptr))($3); }
- | exp '+' exp { $$ = $1 + $3; }
- | exp '-' exp { $$ = $1 - $3; }
- | exp '*' exp { $$ = $1 * $3; }
- | exp '/' exp { $$ = $1 / $3; }
- | '-' exp %prec NEG { $$ = -$2; }
- | exp '^' exp { $$ = pow ($1, $3); }
- | '(' exp ')' { $$ = $2; }
- ;
- /* End of grammar */
- %%
-
-
-File: bison.info, Node: Mfcalc Symtab, Prev: Mfcalc Rules, Up: Multi-function Calc
-
-The `mfcalc' Symbol Table
--------------------------
-
- The multi-function calculator requires a symbol table to keep track
-of the names and meanings of variables and functions. This doesn't
-affect the grammar rules (except for the actions) or the Bison
-declarations, but it requires some additional C functions for support.
-
- The symbol table itself consists of a linked list of records. Its
-definition, which is kept in the header `calc.h', is as follows. It
-provides for either functions or variables to be placed in the table.
-
- /* Data type for links in the chain of symbols. */
- struct symrec
- {
- char *name; /* name of symbol */
- int type; /* type of symbol: either VAR or FNCT */
- union {
- double var; /* value of a VAR */
- double (*fnctptr)(); /* value of a FNCT */
- } value;
- struct symrec *next; /* link field */
- };
-
- typedef struct symrec symrec;
-
- /* The symbol table: a chain of `struct symrec'. */
- extern symrec *sym_table;
-
- symrec *putsym ();
- symrec *getsym ();
-
- The new version of `main' includes a call to `init_table', a
-function that initializes the symbol table. Here it is, and
-`init_table' as well:
-
- #include <stdio.h>
-
- main ()
- {
- init_table ();
- yyparse ();
- }
-
- yyerror (s) /* Called by yyparse on error */
- char *s;
- {
- printf ("%s\n", s);
- }
-
- struct init
- {
- char *fname;
- double (*fnct)();
- };
-
- struct init arith_fncts[]
- = {
- "sin", sin,
- "cos", cos,
- "atan", atan,
- "ln", log,
- "exp", exp,
- "sqrt", sqrt,
- 0, 0
- };
-
- /* The symbol table: a chain of `struct symrec'. */
- symrec *sym_table = (symrec *)0;
-
- init_table () /* puts arithmetic functions in table. */
- {
- int i;
- symrec *ptr;
- for (i = 0; arith_fncts[i].fname != 0; i++)
- {
- ptr = putsym (arith_fncts[i].fname, FNCT);
- ptr->value.fnctptr = arith_fncts[i].fnct;
- }
- }
-
- By simply editing the initialization list and adding the necessary
-include files, you can add additional functions to the calculator.
-
- Two important functions allow look-up and installation of symbols in
-the symbol table. The function `putsym' is passed a name and the type
-(`VAR' or `FNCT') of the object to be installed. The object is linked
-to the front of the list, and a pointer to the object is returned. The
-function `getsym' is passed the name of the symbol to look up. If
-found, a pointer to that symbol is returned; otherwise zero is returned.
-
- symrec *
- putsym (sym_name,sym_type)
- char *sym_name;
- int sym_type;
- {
- symrec *ptr;
- ptr = (symrec *) malloc (sizeof (symrec));
- ptr->name = (char *) malloc (strlen (sym_name) + 1);
- strcpy (ptr->name,sym_name);
- ptr->type = sym_type;
- ptr->value.var = 0; /* set value to 0 even if fctn. */
- ptr->next = (struct symrec *)sym_table;
- sym_table = ptr;
- return ptr;
- }
-
- symrec *
- getsym (sym_name)
- char *sym_name;
- {
- symrec *ptr;
- for (ptr = sym_table; ptr != (symrec *) 0;
- ptr = (symrec *)ptr->next)
- if (strcmp (ptr->name,sym_name) == 0)
- return ptr;
- return 0;
- }
-
- The function `yylex' must now recognize variables, numeric values,
-and the single-character arithmetic operators. Strings of alphanumeric
-characters with a leading nondigit are recognized as either variables or
-functions depending on what the symbol table says about them.
-
- The string is passed to `getsym' for look up in the symbol table. If
-the name appears in the table, a pointer to its location and its type
-(`VAR' or `FNCT') is returned to `yyparse'. If it is not already in
-the table, then it is installed as a `VAR' using `putsym'. Again, a
-pointer and its type (which must be `VAR') is returned to `yyparse'.
-
- No change is needed in the handling of numeric values and arithmetic
-operators in `yylex'.
-
- #include <ctype.h>
- yylex ()
- {
- int c;
-
- /* Ignore whitespace, get first nonwhite character. */
- while ((c = getchar ()) == ' ' || c == '\t');
-
- if (c == EOF)
- return 0;
-
- /* Char starts a number => parse the number. */
- if (c == '.' || isdigit (c))
- {
- ungetc (c, stdin);
- scanf ("%lf", &yylval.val);
- return NUM;
- }
-
- /* Char starts an identifier => read the name. */
- if (isalpha (c))
- {
- symrec *s;
- static char *symbuf = 0;
- static int length = 0;
- int i;
-
- /* Initially make the buffer long enough
- for a 40-character symbol name. */
- if (length == 0)
- length = 40, symbuf = (char *)malloc (length + 1);
-
- i = 0;
- do
-
- {
- /* If buffer is full, make it bigger. */
- if (i == length)
- {
- length *= 2;
- symbuf = (char *)realloc (symbuf, length + 1);
- }
- /* Add this character to the buffer. */
- symbuf[i++] = c;
- /* Get another character. */
- c = getchar ();
- }
-
- while (c != EOF && isalnum (c));
-
- ungetc (c, stdin);
- symbuf[i] = '\0';
-
- s = getsym (symbuf);
- if (s == 0)
- s = putsym (symbuf, VAR);
- yylval.tptr = s;
- return s->type;
- }
-
- /* Any other character is a token by itself. */
- return c;
- }
-
- This program is both powerful and flexible. You may easily add new
-functions, and it is a simple job to modify this code to install
-predefined variables such as `pi' or `e' as well.
-
-
-File: bison.info, Node: Exercises, Prev: Multi-function Calc, Up: Examples
-
-Exercises
-=========
-
- 1. Add some new functions from `math.h' to the initialization list.
-
- 2. Add another array that contains constants and their values. Then
- modify `init_table' to add these constants to the symbol table.
- It will be easiest to give the constants type `VAR'.
-
- 3. Make the program report an error if the user refers to an
- uninitialized variable in any way except to store a value in it.
-
-
-File: bison.info, Node: Grammar File, Next: Interface, Prev: Examples, Up: Top
-
-Bison Grammar Files
-*******************
-
- Bison takes as input a context-free grammar specification and
-produces a C-language function that recognizes correct instances of the
-grammar.
-
- The Bison grammar input file conventionally has a name ending in
-`.y'.
-
-* Menu:
-
-* Grammar Outline:: Overall layout of the grammar file.
-* Symbols:: Terminal and nonterminal symbols.
-* Rules:: How to write grammar rules.
-* Recursion:: Writing recursive rules.
-* Semantics:: Semantic values and actions.
-* Declarations:: All kinds of Bison declarations are described here.
-* Multiple Parsers:: Putting more than one Bison parser in one program.
-
-
-File: bison.info, Node: Grammar Outline, Next: Symbols, Up: Grammar File
-
-Outline of a Bison Grammar
-==========================
-
- A Bison grammar file has four main sections, shown here with the
-appropriate delimiters:
-
- %{
- C DECLARATIONS
- %}
-
- BISON DECLARATIONS
-
- %%
- GRAMMAR RULES
- %%
-
- ADDITIONAL C CODE
-
- Comments enclosed in `/* ... */' may appear in any of the sections.
-
-* Menu:
-
-* C Declarations:: Syntax and usage of the C declarations section.
-* Bison Declarations:: Syntax and usage of the Bison declarations section.
-* Grammar Rules:: Syntax and usage of the grammar rules section.
-* C Code:: Syntax and usage of the additional C code section.
-
-
-File: bison.info, Node: C Declarations, Next: Bison Declarations, Up: Grammar Outline
-
-The C Declarations Section
---------------------------
-
- The C DECLARATIONS section contains macro definitions and
-declarations of functions and variables that are used in the actions in
-the grammar rules. These are copied to the beginning of the parser
-file so that they precede the definition of `yyparse'. You can use
-`#include' to get the declarations from a header file. If you don't
-need any C declarations, you may omit the `%{' and `%}' delimiters that
-bracket this section.
-
-
-File: bison.info, Node: Bison Declarations, Next: Grammar Rules, Prev: C Declarations, Up: Grammar Outline
-
-The Bison Declarations Section
-------------------------------
-
- The BISON DECLARATIONS section contains declarations that define
-terminal and nonterminal symbols, specify precedence, and so on. In
-some simple grammars you may not need any declarations. *Note Bison
-Declarations: Declarations.
-
-
-File: bison.info, Node: Grammar Rules, Next: C Code, Prev: Bison Declarations, Up: Grammar Outline
-
-The Grammar Rules Section
--------------------------
-
- The "grammar rules" section contains one or more Bison grammar
-rules, and nothing else. *Note Syntax of Grammar Rules: Rules.
-
- There must always be at least one grammar rule, and the first `%%'
-(which precedes the grammar rules) may never be omitted even if it is
-the first thing in the file.
-
-
-File: bison.info, Node: C Code, Prev: Grammar Rules, Up: Grammar Outline
-
-The Additional C Code Section
------------------------------
-
- The ADDITIONAL C CODE section is copied verbatim to the end of the
-parser file, just as the C DECLARATIONS section is copied to the
-beginning. This is the most convenient place to put anything that you
-want to have in the parser file but which need not come before the
-definition of `yyparse'. For example, the definitions of `yylex' and
-`yyerror' often go here. *Note Parser C-Language Interface: Interface.
-
- If the last section is empty, you may omit the `%%' that separates it
-from the grammar rules.
-
- The Bison parser itself contains many static variables whose names
-start with `yy' and many macros whose names start with `YY'. It is a
-good idea to avoid using any such names (except those documented in this
-manual) in the additional C code section of the grammar file.
-
-
-File: bison.info, Node: Symbols, Next: Rules, Prev: Grammar Outline, Up: Grammar File
-
-Symbols, Terminal and Nonterminal
-=================================
-
- "Symbols" in Bison grammars represent the grammatical classifications
-of the language.
-
- A "terminal symbol" (also known as a "token type") represents a
-class of syntactically equivalent tokens. You use the symbol in grammar
-rules to mean that a token in that class is allowed. The symbol is
-represented in the Bison parser by a numeric code, and the `yylex'
-function returns a token type code to indicate what kind of token has
-been read. You don't need to know what the code value is; you can use
-the symbol to stand for it.
-
- A "nonterminal symbol" stands for a class of syntactically equivalent
-groupings. The symbol name is used in writing grammar rules. By
-convention, it should be all lower case.
-
- Symbol names can contain letters, digits (not at the beginning),
-underscores and periods. Periods make sense only in nonterminals.
-
- There are three ways of writing terminal symbols in the grammar:
-
- * A "named token type" is written with an identifier, like an
- identifier in C. By convention, it should be all upper case. Each
- such name must be defined with a Bison declaration such as
- `%token'. *Note Token Type Names: Token Decl.
-
- * A "character token type" (or "literal character token") is written
- in the grammar using the same syntax used in C for character
- constants; for example, `'+'' is a character token type. A
- character token type doesn't need to be declared unless you need to
- specify its semantic value data type (*note Data Types of Semantic
- Values: Value Type.), associativity, or precedence (*note Operator
- Precedence: Precedence.).
-
- By convention, a character token type is used only to represent a
- token that consists of that particular character. Thus, the token
- type `'+'' is used to represent the character `+' as a token.
- Nothing enforces this convention, but if you depart from it, your
- program will confuse other readers.
-
- All the usual escape sequences used in character literals in C can
- be used in Bison as well, but you must not use the null character
- as a character literal because its ASCII code, zero, is the code
- `yylex' returns for end-of-input (*note Calling Convention for
- `yylex': Calling Convention.).
-
- * A "literal string token" is written like a C string constant; for
- example, `"<="' is a literal string token. A literal string token
- doesn't need to be declared unless you need to specify its semantic
- value data type (*note Value Type::.), associativity, precedence
- (*note Precedence::.).
-
- You can associate the literal string token with a symbolic name as
- an alias, using the `%token' declaration (*note Token
- Declarations: Token Decl.). If you don't do that, the lexical
- analyzer has to retrieve the token number for the literal string
- token from the `yytname' table (*note Calling Convention::.).
-
- *WARNING*: literal string tokens do not work in Yacc.
-
- By convention, a literal string token is used only to represent a
- token that consists of that particular string. Thus, you should
- use the token type `"<="' to represent the string `<=' as a token.
- Bison does not enforces this convention, but if you depart from
- it, people who read your program will be confused.
-
- All the escape sequences used in string literals in C can be used
- in Bison as well. A literal string token must contain two or more
- characters; for a token containing just one character, use a
- character token (see above).
-
- How you choose to write a terminal symbol has no effect on its
-grammatical meaning. That depends only on where it appears in rules and
-on when the parser function returns that symbol.
-
- The value returned by `yylex' is always one of the terminal symbols
-(or 0 for end-of-input). Whichever way you write the token type in the
-grammar rules, you write it the same way in the definition of `yylex'.
-The numeric code for a character token type is simply the ASCII code for
-the character, so `yylex' can use the identical character constant to
-generate the requisite code. Each named token type becomes a C macro in
-the parser file, so `yylex' can use the name to stand for the code.
-(This is why periods don't make sense in terminal symbols.) *Note
-Calling Convention for `yylex': Calling Convention.
-
- If `yylex' is defined in a separate file, you need to arrange for the
-token-type macro definitions to be available there. Use the `-d'
-option when you run Bison, so that it will write these macro definitions
-into a separate header file `NAME.tab.h' which you can include in the
-other source files that need it. *Note Invoking Bison: Invocation.
-
- The symbol `error' is a terminal symbol reserved for error recovery
-(*note Error Recovery::.); you shouldn't use it for any other purpose.
-In particular, `yylex' should never return this value.
-
-
-File: bison.info, Node: Rules, Next: Recursion, Prev: Symbols, Up: Grammar File
-
-Syntax of Grammar Rules
-=======================
-
- A Bison grammar rule has the following general form:
-
- RESULT: COMPONENTS...
- ;
-
-where RESULT is the nonterminal symbol that this rule describes and
-COMPONENTS are various terminal and nonterminal symbols that are put
-together by this rule (*note Symbols::.).
-
- For example,
-
- exp: exp '+' exp
- ;
-
-says that two groupings of type `exp', with a `+' token in between, can
-be combined into a larger grouping of type `exp'.
-
- Whitespace in rules is significant only to separate symbols. You
-can add extra whitespace as you wish.
-
- Scattered among the components can be ACTIONS that determine the
-semantics of the rule. An action looks like this:
-
- {C STATEMENTS}
-
-Usually there is only one action and it follows the components. *Note
-Actions::.
-
- Multiple rules for the same RESULT can be written separately or can
-be joined with the vertical-bar character `|' as follows:
-
- RESULT: RULE1-COMPONENTS...
- | RULE2-COMPONENTS...
- ...
- ;
-
-They are still considered distinct rules even when joined in this way.
-
- If COMPONENTS in a rule is empty, it means that RESULT can match the
-empty string. For example, here is how to define a comma-separated
-sequence of zero or more `exp' groupings:
-
- expseq: /* empty */
- | expseq1
- ;
-
- expseq1: exp
- | expseq1 ',' exp
- ;
-
-It is customary to write a comment `/* empty */' in each rule with no
-components.
-
-
-File: bison.info, Node: Recursion, Next: Semantics, Prev: Rules, Up: Grammar File
-
-Recursive Rules
-===============
-
- A rule is called "recursive" when its RESULT nonterminal appears
-also on its right hand side. Nearly all Bison grammars need to use
-recursion, because that is the only way to define a sequence of any
-number of somethings. Consider this recursive definition of a
-comma-separated sequence of one or more expressions:
-
- expseq1: exp
- | expseq1 ',' exp
- ;
-
-Since the recursive use of `expseq1' is the leftmost symbol in the
-right hand side, we call this "left recursion". By contrast, here the
-same construct is defined using "right recursion":
-
- expseq1: exp
- | exp ',' expseq1
- ;
-
-Any kind of sequence can be defined using either left recursion or
-right recursion, but you should always use left recursion, because it
-can parse a sequence of any number of elements with bounded stack
-space. Right recursion uses up space on the Bison stack in proportion
-to the number of elements in the sequence, because all the elements
-must be shifted onto the stack before the rule can be applied even
-once. *Note The Bison Parser Algorithm: Algorithm, for further
-explanation of this.
-
- "Indirect" or "mutual" recursion occurs when the result of the rule
-does not appear directly on its right hand side, but does appear in
-rules for other nonterminals which do appear on its right hand side.
-
- For example:
-
- expr: primary
- | primary '+' primary
- ;
-
- primary: constant
- | '(' expr ')'
- ;
-
-defines two mutually-recursive nonterminals, since each refers to the
-other.
-
-
-File: bison.info, Node: Semantics, Next: Declarations, Prev: Recursion, Up: Grammar File
-
-Defining Language Semantics
-===========================
-
- The grammar rules for a language determine only the syntax. The
-semantics are determined by the semantic values associated with various
-tokens and groupings, and by the actions taken when various groupings
-are recognized.
-
- For example, the calculator calculates properly because the value
-associated with each expression is the proper number; it adds properly
-because the action for the grouping `X + Y' is to add the numbers
-associated with X and Y.
-
-* Menu:
-
-* Value Type:: Specifying one data type for all semantic values.
-* Multiple Types:: Specifying several alternative data types.
-* Actions:: An action is the semantic definition of a grammar rule.
-* Action Types:: Specifying data types for actions to operate on.
-* Mid-Rule Actions:: Most actions go at the end of a rule.
- This says when, why and how to use the exceptional
- action in the middle of a rule.
-
-
-File: bison.info, Node: Value Type, Next: Multiple Types, Up: Semantics
-
-Data Types of Semantic Values
------------------------------
-
- In a simple program it may be sufficient to use the same data type
-for the semantic values of all language constructs. This was true in
-the RPN and infix calculator examples (*note Reverse Polish Notation
-Calculator: RPN Calc.).
-
- Bison's default is to use type `int' for all semantic values. To
-specify some other type, define `YYSTYPE' as a macro, like this:
-
- #define YYSTYPE double
-
-This macro definition must go in the C declarations section of the
-grammar file (*note Outline of a Bison Grammar: Grammar Outline.).
-
-
-File: bison.info, Node: Multiple Types, Next: Actions, Prev: Value Type, Up: Semantics
-
-More Than One Value Type
-------------------------
-
- In most programs, you will need different data types for different
-kinds of tokens and groupings. For example, a numeric constant may
-need type `int' or `long', while a string constant needs type `char *',
-and an identifier might need a pointer to an entry in the symbol table.
-
- To use more than one data type for semantic values in one parser,
-Bison requires you to do two things:
-
- * Specify the entire collection of possible data types, with the
- `%union' Bison declaration (*note The Collection of Value Types:
- Union Decl.).
-
- * Choose one of those types for each symbol (terminal or nonterminal)
- for which semantic values are used. This is done for tokens with
- the `%token' Bison declaration (*note Token Type Names: Token
- Decl.) and for groupings with the `%type' Bison declaration (*note
- Nonterminal Symbols: Type Decl.).
-
-
-File: bison.info, Node: Actions, Next: Action Types, Prev: Multiple Types, Up: Semantics
-
-Actions
--------
-
- An action accompanies a syntactic rule and contains C code to be
-executed each time an instance of that rule is recognized. The task of
-most actions is to compute a semantic value for the grouping built by
-the rule from the semantic values associated with tokens or smaller
-groupings.
-
- An action consists of C statements surrounded by braces, much like a
-compound statement in C. It can be placed at any position in the rule;
-it is executed at that position. Most rules have just one action at
-the end of the rule, following all the components. Actions in the
-middle of a rule are tricky and used only for special purposes (*note
-Actions in Mid-Rule: Mid-Rule Actions.).
-
- The C code in an action can refer to the semantic values of the
-components matched by the rule with the construct `$N', which stands for
-the value of the Nth component. The semantic value for the grouping
-being constructed is `$$'. (Bison translates both of these constructs
-into array element references when it copies the actions into the parser
-file.)
-
- Here is a typical example:
-
- exp: ...
- | exp '+' exp
- { $$ = $1 + $3; }
-
-This rule constructs an `exp' from two smaller `exp' groupings
-connected by a plus-sign token. In the action, `$1' and `$3' refer to
-the semantic values of the two component `exp' groupings, which are the
-first and third symbols on the right hand side of the rule. The sum is
-stored into `$$' so that it becomes the semantic value of the
-addition-expression just recognized by the rule. If there were a
-useful semantic value associated with the `+' token, it could be
-referred to as `$2'.
-
- If you don't specify an action for a rule, Bison supplies a default:
-`$$ = $1'. Thus, the value of the first symbol in the rule becomes the
-value of the whole rule. Of course, the default rule is valid only if
-the two data types match. There is no meaningful default action for an
-empty rule; every empty rule must have an explicit action unless the
-rule's value does not matter.
-
- `$N' with N zero or negative is allowed for reference to tokens and
-groupings on the stack *before* those that match the current rule.
-This is a very risky practice, and to use it reliably you must be
-certain of the context in which the rule is applied. Here is a case in
-which you can use this reliably:
-
- foo: expr bar '+' expr { ... }
- | expr bar '-' expr { ... }
- ;
-
- bar: /* empty */
- { previous_expr = $0; }
- ;
-
- As long as `bar' is used only in the fashion shown here, `$0' always
-refers to the `expr' which precedes `bar' in the definition of `foo'.
-
-
-File: bison.info, Node: Action Types, Next: Mid-Rule Actions, Prev: Actions, Up: Semantics
-
-Data Types of Values in Actions
--------------------------------
-
- If you have chosen a single data type for semantic values, the `$$'
-and `$N' constructs always have that data type.
-
- If you have used `%union' to specify a variety of data types, then
-you must declare a choice among these types for each terminal or
-nonterminal symbol that can have a semantic value. Then each time you
-use `$$' or `$N', its data type is determined by which symbol it refers
-to in the rule. In this example,
-
- exp: ...
- | exp '+' exp
- { $$ = $1 + $3; }
-
-`$1' and `$3' refer to instances of `exp', so they all have the data
-type declared for the nonterminal symbol `exp'. If `$2' were used, it
-would have the data type declared for the terminal symbol `'+'',
-whatever that might be.
-
- Alternatively, you can specify the data type when you refer to the
-value, by inserting `<TYPE>' after the `$' at the beginning of the
-reference. For example, if you have defined types as shown here:
-
- %union {
- int itype;
- double dtype;
- }
-
-then you can write `$<itype>1' to refer to the first subunit of the
-rule as an integer, or `$<dtype>1' to refer to it as a double.
-
diff -rup --new-file baseline/fsf/bison/bison.info-3 amiga/fsf/bison/bison.info-3
--- baseline/fsf/bison/bison.info-3 Sat Feb 17 09:46:07 1996
+++ amiga/fsf/bison/bison.info-3 Wed Dec 31 17:00:00 1969
@@ -1,1301 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-File: bison.info, Node: Mid-Rule Actions, Prev: Action Types, Up: Semantics
-
-Actions in Mid-Rule
--------------------
-
- Occasionally it is useful to put an action in the middle of a rule.
-These actions are written just like usual end-of-rule actions, but they
-are executed before the parser even recognizes the following components.
-
- A mid-rule action may refer to the components preceding it using
-`$N', but it may not refer to subsequent components because it is run
-before they are parsed.
-
- The mid-rule action itself counts as one of the components of the
-rule. This makes a difference when there is another action later in
-the same rule (and usually there is another at the end): you have to
-count the actions along with the symbols when working out which number
-N to use in `$N'.
-
- The mid-rule action can also have a semantic value. The action can
-set its value with an assignment to `$$', and actions later in the rule
-can refer to the value using `$N'. Since there is no symbol to name
-the action, there is no way to declare a data type for the value in
-advance, so you must use the `$<...>' construct to specify a data type
-each time you refer to this value.
-
- There is no way to set the value of the entire rule with a mid-rule
-action, because assignments to `$$' do not have that effect. The only
-way to set the value for the entire rule is with an ordinary action at
-the end of the rule.
-
- Here is an example from a hypothetical compiler, handling a `let'
-statement that looks like `let (VARIABLE) STATEMENT' and serves to
-create a variable named VARIABLE temporarily for the duration of
-STATEMENT. To parse this construct, we must put VARIABLE into the
-symbol table while STATEMENT is parsed, then remove it afterward. Here
-is how it is done:
-
- stmt: LET '(' var ')'
- { $<context>$ = push_context ();
- declare_variable ($3); }
- stmt { $$ = $6;
- pop_context ($<context>5); }
-
-As soon as `let (VARIABLE)' has been recognized, the first action is
-run. It saves a copy of the current semantic context (the list of
-accessible variables) as its semantic value, using alternative
-`context' in the data-type union. Then it calls `declare_variable' to
-add the new variable to that list. Once the first action is finished,
-the embedded statement `stmt' can be parsed. Note that the mid-rule
-action is component number 5, so the `stmt' is component number 6.
-
- After the embedded statement is parsed, its semantic value becomes
-the value of the entire `let'-statement. Then the semantic value from
-the earlier action is used to restore the prior list of variables. This
-removes the temporary `let'-variable from the list so that it won't
-appear to exist while the rest of the program is parsed.
-
- Taking action before a rule is completely recognized often leads to
-conflicts since the parser must commit to a parse in order to execute
-the action. For example, the following two rules, without mid-rule
-actions, can coexist in a working parser because the parser can shift
-the open-brace token and look at what follows before deciding whether
-there is a declaration or not:
-
- compound: '{' declarations statements '}'
- | '{' statements '}'
- ;
-
-But when we add a mid-rule action as follows, the rules become
-nonfunctional:
-
- compound: { prepare_for_local_variables (); }
- '{' declarations statements '}'
- | '{' statements '}'
- ;
-
-Now the parser is forced to decide whether to run the mid-rule action
-when it has read no farther than the open-brace. In other words, it
-must commit to using one rule or the other, without sufficient
-information to do it correctly. (The open-brace token is what is called
-the "look-ahead" token at this time, since the parser is still deciding
-what to do about it. *Note Look-Ahead Tokens: Look-Ahead.)
-
- You might think that you could correct the problem by putting
-identical actions into the two rules, like this:
-
- compound: { prepare_for_local_variables (); }
- '{' declarations statements '}'
- | { prepare_for_local_variables (); }
- '{' statements '}'
- ;
-
-But this does not help, because Bison does not realize that the two
-actions are identical. (Bison never tries to understand the C code in
-an action.)
-
- If the grammar is such that a declaration can be distinguished from a
-statement by the first token (which is true in C), then one solution
-which does work is to put the action after the open-brace, like this:
-
- compound: '{' { prepare_for_local_variables (); }
- declarations statements '}'
- | '{' statements '}'
- ;
-
-Now the first token of the following declaration or statement, which
-would in any case tell Bison which rule to use, can still do so.
-
- Another solution is to bury the action inside a nonterminal symbol
-which serves as a subroutine:
-
- subroutine: /* empty */
- { prepare_for_local_variables (); }
- ;
-
- compound: subroutine
- '{' declarations statements '}'
- | subroutine
- '{' statements '}'
- ;
-
-Now Bison can execute the action in the rule for `subroutine' without
-deciding which rule for `compound' it will eventually use. Note that
-the action is now at the end of its rule. Any mid-rule action can be
-converted to an end-of-rule action in this way, and this is what Bison
-actually does to implement mid-rule actions.
-
-
-File: bison.info, Node: Declarations, Next: Multiple Parsers, Prev: Semantics, Up: Grammar File
-
-Bison Declarations
-==================
-
- The "Bison declarations" section of a Bison grammar defines the
-symbols used in formulating the grammar and the data types of semantic
-values. *Note Symbols::.
-
- All token type names (but not single-character literal tokens such as
-`'+'' and `'*'') must be declared. Nonterminal symbols must be
-declared if you need to specify which data type to use for the semantic
-value (*note More Than One Value Type: Multiple Types.).
-
- The first rule in the file also specifies the start symbol, by
-default. If you want some other symbol to be the start symbol, you
-must declare it explicitly (*note Languages and Context-Free Grammars:
-Language and Grammar.).
-
-* Menu:
-
-* Token Decl:: Declaring terminal symbols.
-* Precedence Decl:: Declaring terminals with precedence and associativity.
-* Union Decl:: Declaring the set of all semantic value types.
-* Type Decl:: Declaring the choice of type for a nonterminal symbol.
-* Expect Decl:: Suppressing warnings about shift/reduce conflicts.
-* Start Decl:: Specifying the start symbol.
-* Pure Decl:: Requesting a reentrant parser.
-* Decl Summary:: Table of all Bison declarations.
-
-
-File: bison.info, Node: Token Decl, Next: Precedence Decl, Up: Declarations
-
-Token Type Names
-----------------
-
- The basic way to declare a token type name (terminal symbol) is as
-follows:
-
- %token NAME
-
- Bison will convert this into a `#define' directive in the parser, so
-that the function `yylex' (if it is in this file) can use the name NAME
-to stand for this token type's code.
-
- Alternatively, you can use `%left', `%right', or `%nonassoc' instead
-of `%token', if you wish to specify precedence. *Note Operator
-Precedence: Precedence Decl.
-
- You can explicitly specify the numeric code for a token type by
-appending an integer value in the field immediately following the token
-name:
-
- %token NUM 300
-
-It is generally best, however, to let Bison choose the numeric codes for
-all token types. Bison will automatically select codes that don't
-conflict with each other or with ASCII characters.
-
- In the event that the stack type is a union, you must augment the
-`%token' or other token declaration to include the data type
-alternative delimited by angle-brackets (*note More Than One Value
-Type: Multiple Types.).
-
- For example:
-
- %union { /* define stack type */
- double val;
- symrec *tptr;
- }
- %token <val> NUM /* define token NUM and its type */
-
- You can associate a literal string token with a token type name by
-writing the literal string at the end of a `%token' declaration which
-declares the name. For example:
-
- %token arrow "=>"
-
-For example, a grammar for the C language might specify these names with
-equivalent literal string tokens:
-
- %token <operator> OR "||"
- %token <operator> LE 134 "<="
- %left OR "<="
-
-Once you equate the literal string and the token name, you can use them
-interchangeably in further declarations or the grammar rules. The
-`yylex' function can use the token name or the literal string to obtain
-the token type code number (*note Calling Convention::.).
-
-
-File: bison.info, Node: Precedence Decl, Next: Union Decl, Prev: Token Decl, Up: Declarations
-
-Operator Precedence
--------------------
-
- Use the `%left', `%right' or `%nonassoc' declaration to declare a
-token and specify its precedence and associativity, all at once. These
-are called "precedence declarations". *Note Operator Precedence:
-Precedence, for general information on operator precedence.
-
- The syntax of a precedence declaration is the same as that of
-`%token': either
-
- %left SYMBOLS...
-
-or
-
- %left <TYPE> SYMBOLS...
-
- And indeed any of these declarations serves the purposes of `%token'.
-But in addition, they specify the associativity and relative precedence
-for all the SYMBOLS:
-
- * The associativity of an operator OP determines how repeated uses
- of the operator nest: whether `X OP Y OP Z' is parsed by grouping
- X with Y first or by grouping Y with Z first. `%left' specifies
- left-associativity (grouping X with Y first) and `%right'
- specifies right-associativity (grouping Y with Z first).
- `%nonassoc' specifies no associativity, which means that `X OP Y
- OP Z' is considered a syntax error.
-
- * The precedence of an operator determines how it nests with other
- operators. All the tokens declared in a single precedence
- declaration have equal precedence and nest together according to
- their associativity. When two tokens declared in different
- precedence declarations associate, the one declared later has the
- higher precedence and is grouped first.
-
-
-File: bison.info, Node: Union Decl, Next: Type Decl, Prev: Precedence Decl, Up: Declarations
-
-The Collection of Value Types
------------------------------
-
- The `%union' declaration specifies the entire collection of possible
-data types for semantic values. The keyword `%union' is followed by a
-pair of braces containing the same thing that goes inside a `union' in
-C.
-
- For example:
-
- %union {
- double val;
- symrec *tptr;
- }
-
-This says that the two alternative types are `double' and `symrec *'.
-They are given names `val' and `tptr'; these names are used in the
-`%token' and `%type' declarations to pick one of the types for a
-terminal or nonterminal symbol (*note Nonterminal Symbols: Type Decl.).
-
- Note that, unlike making a `union' declaration in C, you do not write
-a semicolon after the closing brace.
-
-
-File: bison.info, Node: Type Decl, Next: Expect Decl, Prev: Union Decl, Up: Declarations
-
-Nonterminal Symbols
--------------------
-
-When you use `%union' to specify multiple value types, you must declare
-the value type of each nonterminal symbol for which values are used.
-This is done with a `%type' declaration, like this:
-
- %type <TYPE> NONTERMINAL...
-
-Here NONTERMINAL is the name of a nonterminal symbol, and TYPE is the
-name given in the `%union' to the alternative that you want (*note The
-Collection of Value Types: Union Decl.). You can give any number of
-nonterminal symbols in the same `%type' declaration, if they have the
-same value type. Use spaces to separate the symbol names.
-
- You can also declare the value type of a terminal symbol. To do
-this, use the same `<TYPE>' construction in a declaration for the
-terminal symbol. All kinds of token declarations allow `<TYPE>'.
-
-
-File: bison.info, Node: Expect Decl, Next: Start Decl, Prev: Type Decl, Up: Declarations
-
-Suppressing Conflict Warnings
------------------------------
-
- Bison normally warns if there are any conflicts in the grammar
-(*note Shift/Reduce Conflicts: Shift/Reduce.), but most real grammars
-have harmless shift/reduce conflicts which are resolved in a
-predictable way and would be difficult to eliminate. It is desirable
-to suppress the warning about these conflicts unless the number of
-conflicts changes. You can do this with the `%expect' declaration.
-
- The declaration looks like this:
-
- %expect N
-
- Here N is a decimal integer. The declaration says there should be no
-warning if there are N shift/reduce conflicts and no reduce/reduce
-conflicts. The usual warning is given if there are either more or fewer
-conflicts, or if there are any reduce/reduce conflicts.
-
- In general, using `%expect' involves these steps:
-
- * Compile your grammar without `%expect'. Use the `-v' option to
- get a verbose list of where the conflicts occur. Bison will also
- print the number of conflicts.
-
- * Check each of the conflicts to make sure that Bison's default
- resolution is what you really want. If not, rewrite the grammar
- and go back to the beginning.
-
- * Add an `%expect' declaration, copying the number N from the number
- which Bison printed.
-
- Now Bison will stop annoying you about the conflicts you have
-checked, but it will warn you again if changes in the grammar result in
-additional conflicts.
-
-
-File: bison.info, Node: Start Decl, Next: Pure Decl, Prev: Expect Decl, Up: Declarations
-
-The Start-Symbol
-----------------
-
- Bison assumes by default that the start symbol for the grammar is
-the first nonterminal specified in the grammar specification section.
-The programmer may override this restriction with the `%start'
-declaration as follows:
-
- %start SYMBOL
-
-
-File: bison.info, Node: Pure Decl, Next: Decl Summary, Prev: Start Decl, Up: Declarations
-
-A Pure (Reentrant) Parser
--------------------------
-
- A "reentrant" program is one which does not alter in the course of
-execution; in other words, it consists entirely of "pure" (read-only)
-code. Reentrancy is important whenever asynchronous execution is
-possible; for example, a nonreentrant program may not be safe to call
-from a signal handler. In systems with multiple threads of control, a
-nonreentrant program must be called only within interlocks.
-
- The Bison parser is not normally a reentrant program, because it uses
-statically allocated variables for communication with `yylex'. These
-variables include `yylval' and `yylloc'.
-
- The Bison declaration `%pure_parser' says that you want the parser
-to be reentrant. It looks like this:
-
- %pure_parser
-
- The effect is that the two communication variables become local
-variables in `yyparse', and a different calling convention is used for
-the lexical analyzer function `yylex'. *Note Calling Conventions for
-Pure Parsers: Pure Calling, for the details of this. The variable
-`yynerrs' also becomes local in `yyparse' (*note The Error Reporting
-Function `yyerror': Error Reporting.). The convention for calling
-`yyparse' itself is unchanged.
-
-
-File: bison.info, Node: Decl Summary, Prev: Pure Decl, Up: Declarations
-
-Bison Declaration Summary
--------------------------
-
- Here is a summary of all Bison declarations:
-
-`%union'
- Declare the collection of data types that semantic values may have
- (*note The Collection of Value Types: Union Decl.).
-
-`%token'
- Declare a terminal symbol (token type name) with no precedence or
- associativity specified (*note Token Type Names: Token Decl.).
-
-`%right'
- Declare a terminal symbol (token type name) that is
- right-associative (*note Operator Precedence: Precedence Decl.).
-
-`%left'
- Declare a terminal symbol (token type name) that is
- left-associative (*note Operator Precedence: Precedence Decl.).
-
-`%nonassoc'
- Declare a terminal symbol (token type name) that is nonassociative
- (using it in a way that would be associative is a syntax error)
- (*note Operator Precedence: Precedence Decl.).
-
-`%type'
- Declare the type of semantic values for a nonterminal symbol
- (*note Nonterminal Symbols: Type Decl.).
-
-`%start'
- Specify the grammar's start symbol (*note The Start-Symbol: Start
- Decl.).
-
-`%expect'
- Declare the expected number of shift-reduce conflicts (*note
- Suppressing Conflict Warnings: Expect Decl.).
-
-`%pure_parser'
- Request a pure (reentrant) parser program (*note A Pure
- (Reentrant) Parser: Pure Decl.).
-
-`%no_lines'
- Don't generate any `#line' preprocessor commands in the parser
- file. Ordinarily Bison writes these commands in the parser file
- so that the C compiler and debuggers will associate errors and
- object code with your source file (the grammar file). This
- directive causes them to associate errors with the parser file,
- treating it an independent source file in its own right.
-
-`%raw'
- The output file `NAME.h' normally defines the tokens with
- Yacc-compatible token numbers. If this option is specified, the
- internal Bison numbers are used instead. (Yacc-compatible numbers
- start at 257 except for single character tokens; Bison assigns
- token numbers sequentially for all tokens starting at 3.)
-
-`%token_table'
- Generate an array of token names in the parser file. The name of
- the array is `yytname'; `yytname[I]' is the name of the token
- whose internal Bison token code number is I. The first three
- elements of `yytname' are always `"$"', `"error"', and
- `"$illegal"'; after these come the symbols defined in the grammar
- file.
-
- For single-character literal tokens and literal string tokens, the
- name in the table includes the single-quote or double-quote
- characters: for example, `"'+'"' is a single-character literal and
- `"\"<=\""' is a literal string token. All the characters of the
- literal string token appear verbatim in the string found in the
- table; even double-quote characters are not escaped. For example,
- if the token consists of three characters `*"*', its string in
- `yytname' contains `"*"*"'. (In C, that would be written as
- `"\"*\"*\""').
-
- When you specify `%token_table', Bison also generates macro
- definitions for macros `YYNTOKENS', `YYNNTS', and `YYNRULES', and
- `YYNSTATES':
-
- `YYNTOKENS'
- The highest token number, plus one.
-
- `YYNNTS'
- The number of non-terminal symbols.
-
- `YYNRULES'
- The number of grammar rules,
-
- `YYNSTATES'
- The number of parser states (*note Parser States::.).
-
-
-File: bison.info, Node: Multiple Parsers, Prev: Declarations, Up: Grammar File
-
-Multiple Parsers in the Same Program
-====================================
-
- Most programs that use Bison parse only one language and therefore
-contain only one Bison parser. But what if you want to parse more than
-one language with the same program? Then you need to avoid a name
-conflict between different definitions of `yyparse', `yylval', and so
-on.
-
- The easy way to do this is to use the option `-p PREFIX' (*note
-Invoking Bison: Invocation.). This renames the interface functions and
-variables of the Bison parser to start with PREFIX instead of `yy'.
-You can use this to give each parser distinct names that do not
-conflict.
-
- The precise list of symbols renamed is `yyparse', `yylex',
-`yyerror', `yynerrs', `yylval', `yychar' and `yydebug'. For example,
-if you use `-p c', the names become `cparse', `clex', and so on.
-
- *All the other variables and macros associated with Bison are not
-renamed.* These others are not global; there is no conflict if the same
-name is used in different parsers. For example, `YYSTYPE' is not
-renamed, but defining this in different ways in different parsers causes
-no trouble (*note Data Types of Semantic Values: Value Type.).
-
- The `-p' option works by adding macro definitions to the beginning
-of the parser source file, defining `yyparse' as `PREFIXparse', and so
-on. This effectively substitutes one name for the other in the entire
-parser file.
-
-
-File: bison.info, Node: Interface, Next: Algorithm, Prev: Grammar File, Up: Top
-
-Parser C-Language Interface
-***************************
-
- The Bison parser is actually a C function named `yyparse'. Here we
-describe the interface conventions of `yyparse' and the other functions
-that it needs to use.
-
- Keep in mind that the parser uses many C identifiers starting with
-`yy' and `YY' for internal purposes. If you use such an identifier
-(aside from those in this manual) in an action or in additional C code
-in the grammar file, you are likely to run into trouble.
-
-* Menu:
-
-* Parser Function:: How to call `yyparse' and what it returns.
-* Lexical:: You must supply a function `yylex'
- which reads tokens.
-* Error Reporting:: You must supply a function `yyerror'.
-* Action Features:: Special features for use in actions.
-
-
-File: bison.info, Node: Parser Function, Next: Lexical, Up: Interface
-
-The Parser Function `yyparse'
-=============================
-
- You call the function `yyparse' to cause parsing to occur. This
-function reads tokens, executes actions, and ultimately returns when it
-encounters end-of-input or an unrecoverable syntax error. You can also
-write an action which directs `yyparse' to return immediately without
-reading further.
-
- The value returned by `yyparse' is 0 if parsing was successful
-(return is due to end-of-input).
-
- The value is 1 if parsing failed (return is due to a syntax error).
-
- In an action, you can cause immediate return from `yyparse' by using
-these macros:
-
-`YYACCEPT'
- Return immediately with value 0 (to report success).
-
-`YYABORT'
- Return immediately with value 1 (to report failure).
-
-
-File: bison.info, Node: Lexical, Next: Error Reporting, Prev: Parser Function, Up: Interface
-
-The Lexical Analyzer Function `yylex'
-=====================================
-
- The "lexical analyzer" function, `yylex', recognizes tokens from the
-input stream and returns them to the parser. Bison does not create
-this function automatically; you must write it so that `yyparse' can
-call it. The function is sometimes referred to as a lexical scanner.
-
- In simple programs, `yylex' is often defined at the end of the Bison
-grammar file. If `yylex' is defined in a separate source file, you
-need to arrange for the token-type macro definitions to be available
-there. To do this, use the `-d' option when you run Bison, so that it
-will write these macro definitions into a separate header file
-`NAME.tab.h' which you can include in the other source files that need
-it. *Note Invoking Bison: Invocation.
-
-* Menu:
-
-* Calling Convention:: How `yyparse' calls `yylex'.
-* Token Values:: How `yylex' must return the semantic value
- of the token it has read.
-* Token Positions:: How `yylex' must return the text position
- (line number, etc.) of the token, if the
- actions want that.
-* Pure Calling:: How the calling convention differs
- in a pure parser (*note A Pure (Reentrant) Parser: Pure Decl.).
-
-
-File: bison.info, Node: Calling Convention, Next: Token Values, Up: Lexical
-
-Calling Convention for `yylex'
-------------------------------
-
- The value that `yylex' returns must be the numeric code for the type
-of token it has just found, or 0 for end-of-input.
-
- When a token is referred to in the grammar rules by a name, that name
-in the parser file becomes a C macro whose definition is the proper
-numeric code for that token type. So `yylex' can use the name to
-indicate that type. *Note Symbols::.
-
- When a token is referred to in the grammar rules by a character
-literal, the numeric code for that character is also the code for the
-token type. So `yylex' can simply return that character code. The
-null character must not be used this way, because its code is zero and
-that is what signifies end-of-input.
-
- Here is an example showing these things:
-
- yylex ()
- {
- ...
- if (c == EOF) /* Detect end of file. */
- return 0;
- ...
- if (c == '+' || c == '-')
- return c; /* Assume token type for `+' is '+'. */
- ...
- return INT; /* Return the type of the token. */
- ...
- }
-
-This interface has been designed so that the output from the `lex'
-utility can be used without change as the definition of `yylex'.
-
- If the grammar uses literal string tokens, there are two ways that
-`yylex' can determine the token type codes for them:
-
- * If the grammar defines symbolic token names as aliases for the
- literal string tokens, `yylex' can use these symbolic names like
- all others. In this case, the use of the literal string tokens in
- the grammar file has no effect on `yylex'.
-
- * `yylex' can find the multi-character token in the `yytname' table.
- The index of the token in the table is the token type's code.
- The name of a multi-character token is recorded in `yytname' with a
- double-quote, the token's characters, and another double-quote.
- The token's characters are not escaped in any way; they appear
- verbatim in the contents of the string in the table.
-
- Here's code for looking up a token in `yytname', assuming that the
- characters of the token are stored in `token_buffer'.
-
- for (i = 0; i < YYNTOKENS; i++)
- {
- if (yytname[i] != 0
- && yytname[i][0] == '"'
- && strncmp (yytname[i] + 1, token_buffer, strlen (token_buffer))
- && yytname[i][strlen (token_buffer) + 1] == '"'
- && yytname[i][strlen (token_buffer) + 2] == 0)
- break;
- }
-
- The `yytname' table is generated only if you use the
- `%token_table' declaration. *Note Decl Summary::.
-
-
-File: bison.info, Node: Token Values, Next: Token Positions, Prev: Calling Convention, Up: Lexical
-
-Semantic Values of Tokens
--------------------------
-
- In an ordinary (nonreentrant) parser, the semantic value of the
-token must be stored into the global variable `yylval'. When you are
-using just one data type for semantic values, `yylval' has that type.
-Thus, if the type is `int' (the default), you might write this in
-`yylex':
-
- ...
- yylval = value; /* Put value onto Bison stack. */
- return INT; /* Return the type of the token. */
- ...
-
- When you are using multiple data types, `yylval''s type is a union
-made from the `%union' declaration (*note The Collection of Value
-Types: Union Decl.). So when you store a token's value, you must use
-the proper member of the union. If the `%union' declaration looks like
-this:
-
- %union {
- int intval;
- double val;
- symrec *tptr;
- }
-
-then the code in `yylex' might look like this:
-
- ...
- yylval.intval = value; /* Put value onto Bison stack. */
- return INT; /* Return the type of the token. */
- ...
-
-
-File: bison.info, Node: Token Positions, Next: Pure Calling, Prev: Token Values, Up: Lexical
-
-Textual Positions of Tokens
----------------------------
-
- If you are using the `@N'-feature (*note Special Features for Use in
-Actions: Action Features.) in actions to keep track of the textual
-locations of tokens and groupings, then you must provide this
-information in `yylex'. The function `yyparse' expects to find the
-textual location of a token just parsed in the global variable
-`yylloc'. So `yylex' must store the proper data in that variable. The
-value of `yylloc' is a structure and you need only initialize the
-members that are going to be used by the actions. The four members are
-called `first_line', `first_column', `last_line' and `last_column'.
-Note that the use of this feature makes the parser noticeably slower.
-
- The data type of `yylloc' has the name `YYLTYPE'.
-
-
-File: bison.info, Node: Pure Calling, Prev: Token Positions, Up: Lexical
-
-Calling Conventions for Pure Parsers
-------------------------------------
-
- When you use the Bison declaration `%pure_parser' to request a pure,
-reentrant parser, the global communication variables `yylval' and
-`yylloc' cannot be used. (*Note A Pure (Reentrant) Parser: Pure Decl.)
-In such parsers the two global variables are replaced by pointers
-passed as arguments to `yylex'. You must declare them as shown here,
-and pass the information back by storing it through those pointers.
-
- yylex (lvalp, llocp)
- YYSTYPE *lvalp;
- YYLTYPE *llocp;
- {
- ...
- *lvalp = value; /* Put value onto Bison stack. */
- return INT; /* Return the type of the token. */
- ...
- }
-
- If the grammar file does not use the `@' constructs to refer to
-textual positions, then the type `YYLTYPE' will not be defined. In
-this case, omit the second argument; `yylex' will be called with only
-one argument.
-
- If you use a reentrant parser, you can optionally pass additional
-parameter information to it in a reentrant way. To do so, define the
-macro `YYPARSE_PARAM' as a variable name. This modifies the `yyparse'
-function to accept one argument, of type `void *', with that name.
-
- When you call `yyparse', pass the address of an object, casting the
-address to `void *'. The grammar actions can refer to the contents of
-the object by casting the pointer value back to its proper type and
-then dereferencing it. Here's an example. Write this in the parser:
-
- %{
- struct parser_control
- {
- int nastiness;
- int randomness;
- };
-
- #define YYPARSE_PARAM parm
- %}
-
-Then call the parser like this:
-
- struct parser_control
- {
- int nastiness;
- int randomness;
- };
-
- ...
-
- {
- struct parser_control foo;
- ... /* Store proper data in `foo'. */
- value = yyparse ((void *) &foo);
- ...
- }
-
-In the grammar actions, use expressions like this to refer to the data:
-
- ((struct parser_control *) parm)->randomness
-
- If you wish to pass the additional parameter data to `yylex', define
-the macro `YYLEX_PARAM' just like `YYPARSE_PARAM', as shown here:
-
- %{
- struct parser_control
- {
- int nastiness;
- int randomness;
- };
-
- #define YYPARSE_PARAM parm
- #define YYLEX_PARAM parm
- %}
-
- You should then define `yylex' to accept one additional
-argument--the value of `parm'. (This makes either two or three
-arguments in total, depending on whether an argument of type `YYLTYPE'
-is passed.) You can declare the argument as a pointer to the proper
-object type, or you can declare it as `void *' and access the contents
-as shown above.
-
- You can use `%pure_parser' to request a reentrant parser without
-also using `YYPARSE_PARAM'. Then you should call `yyparse' with no
-arguments, as usual.
-
-
-File: bison.info, Node: Error Reporting, Next: Action Features, Prev: Lexical, Up: Interface
-
-The Error Reporting Function `yyerror'
-======================================
-
- The Bison parser detects a "parse error" or "syntax error" whenever
-it reads a token which cannot satisfy any syntax rule. A action in the
-grammar can also explicitly proclaim an error, using the macro
-`YYERROR' (*note Special Features for Use in Actions: Action Features.).
-
- The Bison parser expects to report the error by calling an error
-reporting function named `yyerror', which you must supply. It is
-called by `yyparse' whenever a syntax error is found, and it receives
-one argument. For a parse error, the string is normally
-`"parse error"'.
-
- If you define the macro `YYERROR_VERBOSE' in the Bison declarations
-section (*note The Bison Declarations Section: Bison Declarations.),
-then Bison provides a more verbose and specific error message string
-instead of just plain `"parse error"'. It doesn't matter what
-definition you use for `YYERROR_VERBOSE', just whether you define it.
-
- The parser can detect one other kind of error: stack overflow. This
-happens when the input contains constructions that are very deeply
-nested. It isn't likely you will encounter this, since the Bison
-parser extends its stack automatically up to a very large limit. But
-if overflow happens, `yyparse' calls `yyerror' in the usual fashion,
-except that the argument string is `"parser stack overflow"'.
-
- The following definition suffices in simple programs:
-
- yyerror (s)
- char *s;
- {
- fprintf (stderr, "%s\n", s);
- }
-
- After `yyerror' returns to `yyparse', the latter will attempt error
-recovery if you have written suitable error recovery grammar rules
-(*note Error Recovery::.). If recovery is impossible, `yyparse' will
-immediately return 1.
-
- The variable `yynerrs' contains the number of syntax errors
-encountered so far. Normally this variable is global; but if you
-request a pure parser (*note A Pure (Reentrant) Parser: Pure Decl.)
-then it is a local variable which only the actions can access.
-
-
-File: bison.info, Node: Action Features, Prev: Error Reporting, Up: Interface
-
-Special Features for Use in Actions
-===================================
-
- Here is a table of Bison constructs, variables and macros that are
-useful in actions.
-
-`$$'
- Acts like a variable that contains the semantic value for the
- grouping made by the current rule. *Note Actions::.
-
-`$N'
- Acts like a variable that contains the semantic value for the Nth
- component of the current rule. *Note Actions::.
-
-`$<TYPEALT>$'
- Like `$$' but specifies alternative TYPEALT in the union specified
- by the `%union' declaration. *Note Data Types of Values in
- Actions: Action Types.
-
-`$<TYPEALT>N'
- Like `$N' but specifies alternative TYPEALT in the union specified
- by the `%union' declaration. *Note Data Types of Values in
- Actions: Action Types.
-
-`YYABORT;'
- Return immediately from `yyparse', indicating failure. *Note The
- Parser Function `yyparse': Parser Function.
-
-`YYACCEPT;'
- Return immediately from `yyparse', indicating success. *Note The
- Parser Function `yyparse': Parser Function.
-
-`YYBACKUP (TOKEN, VALUE);'
- Unshift a token. This macro is allowed only for rules that reduce
- a single value, and only when there is no look-ahead token. It
- installs a look-ahead token with token type TOKEN and semantic
- value VALUE; then it discards the value that was going to be
- reduced by this rule.
-
- If the macro is used when it is not valid, such as when there is a
- look-ahead token already, then it reports a syntax error with a
- message `cannot back up' and performs ordinary error recovery.
-
- In either case, the rest of the action is not executed.
-
-`YYEMPTY'
- Value stored in `yychar' when there is no look-ahead token.
-
-`YYERROR;'
- Cause an immediate syntax error. This statement initiates error
- recovery just as if the parser itself had detected an error;
- however, it does not call `yyerror', and does not print any
- message. If you want to print an error message, call `yyerror'
- explicitly before the `YYERROR;' statement. *Note Error
- Recovery::.
-
-`YYRECOVERING'
- This macro stands for an expression that has the value 1 when the
- parser is recovering from a syntax error, and 0 the rest of the
- time. *Note Error Recovery::.
-
-`yychar'
- Variable containing the current look-ahead token. (In a pure
- parser, this is actually a local variable within `yyparse'.) When
- there is no look-ahead token, the value `YYEMPTY' is stored in the
- variable. *Note Look-Ahead Tokens: Look-Ahead.
-
-`yyclearin;'
- Discard the current look-ahead token. This is useful primarily in
- error rules. *Note Error Recovery::.
-
-`yyerrok;'
- Resume generating error messages immediately for subsequent syntax
- errors. This is useful primarily in error rules. *Note Error
- Recovery::.
-
-`@N'
- Acts like a structure variable containing information on the line
- numbers and column numbers of the Nth component of the current
- rule. The structure has four members, like this:
-
- struct {
- int first_line, last_line;
- int first_column, last_column;
- };
-
- Thus, to get the starting line number of the third component, use
- `@3.first_line'.
-
- In order for the members of this structure to contain valid
- information, you must make `yylex' supply this information about
- each token. If you need only certain members, then `yylex' need
- only fill in those members.
-
- The use of this feature makes the parser noticeably slower.
-
-
-File: bison.info, Node: Algorithm, Next: Error Recovery, Prev: Interface, Up: Top
-
-The Bison Parser Algorithm
-**************************
-
- As Bison reads tokens, it pushes them onto a stack along with their
-semantic values. The stack is called the "parser stack". Pushing a
-token is traditionally called "shifting".
-
- For example, suppose the infix calculator has read `1 + 5 *', with a
-`3' to come. The stack will have four elements, one for each token
-that was shifted.
-
- But the stack does not always have an element for each token read.
-When the last N tokens and groupings shifted match the components of a
-grammar rule, they can be combined according to that rule. This is
-called "reduction". Those tokens and groupings are replaced on the
-stack by a single grouping whose symbol is the result (left hand side)
-of that rule. Running the rule's action is part of the process of
-reduction, because this is what computes the semantic value of the
-resulting grouping.
-
- For example, if the infix calculator's parser stack contains this:
-
- 1 + 5 * 3
-
-and the next input token is a newline character, then the last three
-elements can be reduced to 15 via the rule:
-
- expr: expr '*' expr;
-
-Then the stack contains just these three elements:
-
- 1 + 15
-
-At this point, another reduction can be made, resulting in the single
-value 16. Then the newline token can be shifted.
-
- The parser tries, by shifts and reductions, to reduce the entire
-input down to a single grouping whose symbol is the grammar's
-start-symbol (*note Languages and Context-Free Grammars: Language and
-Grammar.).
-
- This kind of parser is known in the literature as a bottom-up parser.
-
-* Menu:
-
-* Look-Ahead:: Parser looks one token ahead when deciding what to do.
-* Shift/Reduce:: Conflicts: when either shifting or reduction is valid.
-* Precedence:: Operator precedence works by resolving conflicts.
-* Contextual Precedence:: When an operator's precedence depends on context.
-* Parser States:: The parser is a finite-state-machine with stack.
-* Reduce/Reduce:: When two rules are applicable in the same situation.
-* Mystery Conflicts:: Reduce/reduce conflicts that look unjustified.
-* Stack Overflow:: What happens when stack gets full. How to avoid it.
-
-
-File: bison.info, Node: Look-Ahead, Next: Shift/Reduce, Up: Algorithm
-
-Look-Ahead Tokens
-=================
-
- The Bison parser does *not* always reduce immediately as soon as the
-last N tokens and groupings match a rule. This is because such a
-simple strategy is inadequate to handle most languages. Instead, when a
-reduction is possible, the parser sometimes "looks ahead" at the next
-token in order to decide what to do.
-
- When a token is read, it is not immediately shifted; first it
-becomes the "look-ahead token", which is not on the stack. Now the
-parser can perform one or more reductions of tokens and groupings on
-the stack, while the look-ahead token remains off to the side. When no
-more reductions should take place, the look-ahead token is shifted onto
-the stack. This does not mean that all possible reductions have been
-done; depending on the token type of the look-ahead token, some rules
-may choose to delay their application.
-
- Here is a simple case where look-ahead is needed. These three rules
-define expressions which contain binary addition operators and postfix
-unary factorial operators (`!'), and allow parentheses for grouping.
-
- expr: term '+' expr
- | term
- ;
-
- term: '(' expr ')'
- | term '!'
- | NUMBER
- ;
-
- Suppose that the tokens `1 + 2' have been read and shifted; what
-should be done? If the following token is `)', then the first three
-tokens must be reduced to form an `expr'. This is the only valid
-course, because shifting the `)' would produce a sequence of symbols
-`term ')'', and no rule allows this.
-
- If the following token is `!', then it must be shifted immediately so
-that `2 !' can be reduced to make a `term'. If instead the parser were
-to reduce before shifting, `1 + 2' would become an `expr'. It would
-then be impossible to shift the `!' because doing so would produce on
-the stack the sequence of symbols `expr '!''. No rule allows that
-sequence.
-
- The current look-ahead token is stored in the variable `yychar'.
-*Note Special Features for Use in Actions: Action Features.
-
-
-File: bison.info, Node: Shift/Reduce, Next: Precedence, Prev: Look-Ahead, Up: Algorithm
-
-Shift/Reduce Conflicts
-======================
-
- Suppose we are parsing a language which has if-then and if-then-else
-statements, with a pair of rules like this:
-
- if_stmt:
- IF expr THEN stmt
- | IF expr THEN stmt ELSE stmt
- ;
-
-Here we assume that `IF', `THEN' and `ELSE' are terminal symbols for
-specific keyword tokens.
-
- When the `ELSE' token is read and becomes the look-ahead token, the
-contents of the stack (assuming the input is valid) are just right for
-reduction by the first rule. But it is also legitimate to shift the
-`ELSE', because that would lead to eventual reduction by the second
-rule.
-
- This situation, where either a shift or a reduction would be valid,
-is called a "shift/reduce conflict". Bison is designed to resolve
-these conflicts by choosing to shift, unless otherwise directed by
-operator precedence declarations. To see the reason for this, let's
-contrast it with the other alternative.
-
- Since the parser prefers to shift the `ELSE', the result is to attach
-the else-clause to the innermost if-statement, making these two inputs
-equivalent:
-
- if x then if y then win (); else lose;
-
- if x then do; if y then win (); else lose; end;
-
- But if the parser chose to reduce when possible rather than shift,
-the result would be to attach the else-clause to the outermost
-if-statement, making these two inputs equivalent:
-
- if x then if y then win (); else lose;
-
- if x then do; if y then win (); end; else lose;
-
- The conflict exists because the grammar as written is ambiguous:
-either parsing of the simple nested if-statement is legitimate. The
-established convention is that these ambiguities are resolved by
-attaching the else-clause to the innermost if-statement; this is what
-Bison accomplishes by choosing to shift rather than reduce. (It would
-ideally be cleaner to write an unambiguous grammar, but that is very
-hard to do in this case.) This particular ambiguity was first
-encountered in the specifications of Algol 60 and is called the
-"dangling `else'" ambiguity.
-
- To avoid warnings from Bison about predictable, legitimate
-shift/reduce conflicts, use the `%expect N' declaration. There will be
-no warning as long as the number of shift/reduce conflicts is exactly N.
-*Note Suppressing Conflict Warnings: Expect Decl.
-
- The definition of `if_stmt' above is solely to blame for the
-conflict, but the conflict does not actually appear without additional
-rules. Here is a complete Bison input file that actually manifests the
-conflict:
-
- %token IF THEN ELSE variable
- %%
- stmt: expr
- | if_stmt
- ;
-
- if_stmt:
- IF expr THEN stmt
- | IF expr THEN stmt ELSE stmt
- ;
-
- expr: variable
- ;
-
-
-File: bison.info, Node: Precedence, Next: Contextual Precedence, Prev: Shift/Reduce, Up: Algorithm
-
-Operator Precedence
-===================
-
- Another situation where shift/reduce conflicts appear is in
-arithmetic expressions. Here shifting is not always the preferred
-resolution; the Bison declarations for operator precedence allow you to
-specify when to shift and when to reduce.
-
-* Menu:
-
-* Why Precedence:: An example showing why precedence is needed.
-* Using Precedence:: How to specify precedence in Bison grammars.
-* Precedence Examples:: How these features are used in the previous example.
-* How Precedence:: How they work.
-
-
-File: bison.info, Node: Why Precedence, Next: Using Precedence, Up: Precedence
-
-When Precedence is Needed
--------------------------
-
- Consider the following ambiguous grammar fragment (ambiguous because
-the input `1 - 2 * 3' can be parsed in two different ways):
-
- expr: expr '-' expr
- | expr '*' expr
- | expr '<' expr
- | '(' expr ')'
- ...
- ;
-
-Suppose the parser has seen the tokens `1', `-' and `2'; should it
-reduce them via the rule for the addition operator? It depends on the
-next token. Of course, if the next token is `)', we must reduce;
-shifting is invalid because no single rule can reduce the token
-sequence `- 2 )' or anything starting with that. But if the next token
-is `*' or `<', we have a choice: either shifting or reduction would
-allow the parse to complete, but with different results.
-
- To decide which one Bison should do, we must consider the results.
-If the next operator token OP is shifted, then it must be reduced first
-in order to permit another opportunity to reduce the sum. The result
-is (in effect) `1 - (2 OP 3)'. On the other hand, if the subtraction
-is reduced before shifting OP, the result is `(1 - 2) OP 3'. Clearly,
-then, the choice of shift or reduce should depend on the relative
-precedence of the operators `-' and OP: `*' should be shifted first,
-but not `<'.
-
- What about input such as `1 - 2 - 5'; should this be `(1 - 2) - 5'
-or should it be `1 - (2 - 5)'? For most operators we prefer the
-former, which is called "left association". The latter alternative,
-"right association", is desirable for assignment operators. The choice
-of left or right association is a matter of whether the parser chooses
-to shift or reduce when the stack contains `1 - 2' and the look-ahead
-token is `-': shifting makes right-associativity.
-
-
-File: bison.info, Node: Using Precedence, Next: Precedence Examples, Prev: Why Precedence, Up: Precedence
-
-Specifying Operator Precedence
-------------------------------
-
- Bison allows you to specify these choices with the operator
-precedence declarations `%left' and `%right'. Each such declaration
-contains a list of tokens, which are operators whose precedence and
-associativity is being declared. The `%left' declaration makes all
-those operators left-associative and the `%right' declaration makes
-them right-associative. A third alternative is `%nonassoc', which
-declares that it is a syntax error to find the same operator twice "in a
-row".
-
- The relative precedence of different operators is controlled by the
-order in which they are declared. The first `%left' or `%right'
-declaration in the file declares the operators whose precedence is
-lowest, the next such declaration declares the operators whose
-precedence is a little higher, and so on.
-
-
-File: bison.info, Node: Precedence Examples, Next: How Precedence, Prev: Using Precedence, Up: Precedence
-
-Precedence Examples
--------------------
-
- In our example, we would want the following declarations:
-
- %left '<'
- %left '-'
- %left '*'
-
- In a more complete example, which supports other operators as well,
-we would declare them in groups of equal precedence. For example,
-`'+'' is declared with `'-'':
-
- %left '<' '>' '=' NE LE GE
- %left '+' '-'
- %left '*' '/'
-
-(Here `NE' and so on stand for the operators for "not equal" and so on.
-We assume that these tokens are more than one character long and
-therefore are represented by names, not character literals.)
-
-
-File: bison.info, Node: How Precedence, Prev: Precedence Examples, Up: Precedence
-
-How Precedence Works
---------------------
-
- The first effect of the precedence declarations is to assign
-precedence levels to the terminal symbols declared. The second effect
-is to assign precedence levels to certain rules: each rule gets its
-precedence from the last terminal symbol mentioned in the components.
-(You can also specify explicitly the precedence of a rule. *Note
-Context-Dependent Precedence: Contextual Precedence.)
-
- Finally, the resolution of conflicts works by comparing the
-precedence of the rule being considered with that of the look-ahead
-token. If the token's precedence is higher, the choice is to shift.
-If the rule's precedence is higher, the choice is to reduce. If they
-have equal precedence, the choice is made based on the associativity of
-that precedence level. The verbose output file made by `-v' (*note
-Invoking Bison: Invocation.) says how each conflict was resolved.
-
- Not all rules and not all tokens have precedence. If either the
-rule or the look-ahead token has no precedence, then the default is to
-shift.
-
diff -rup --new-file baseline/fsf/bison/bison.info-4 amiga/fsf/bison/bison.info-4
--- baseline/fsf/bison/bison.info-4 Sat Feb 17 09:46:08 1996
+++ amiga/fsf/bison/bison.info-4 Wed Dec 31 17:00:00 1969
@@ -1,1276 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-File: bison.info, Node: Contextual Precedence, Next: Parser States, Prev: Precedence, Up: Algorithm
-
-Context-Dependent Precedence
-============================
-
- Often the precedence of an operator depends on the context. This
-sounds outlandish at first, but it is really very common. For example,
-a minus sign typically has a very high precedence as a unary operator,
-and a somewhat lower precedence (lower than multiplication) as a binary
-operator.
-
- The Bison precedence declarations, `%left', `%right' and
-`%nonassoc', can only be used once for a given token; so a token has
-only one precedence declared in this way. For context-dependent
-precedence, you need to use an additional mechanism: the `%prec'
-modifier for rules.
-
- The `%prec' modifier declares the precedence of a particular rule by
-specifying a terminal symbol whose precedence should be used for that
-rule. It's not necessary for that symbol to appear otherwise in the
-rule. The modifier's syntax is:
-
- %prec TERMINAL-SYMBOL
-
-and it is written after the components of the rule. Its effect is to
-assign the rule the precedence of TERMINAL-SYMBOL, overriding the
-precedence that would be deduced for it in the ordinary way. The
-altered rule precedence then affects how conflicts involving that rule
-are resolved (*note Operator Precedence: Precedence.).
-
- Here is how `%prec' solves the problem of unary minus. First,
-declare a precedence for a fictitious terminal symbol named `UMINUS'.
-There are no tokens of this type, but the symbol serves to stand for its
-precedence:
-
- ...
- %left '+' '-'
- %left '*'
- %left UMINUS
-
- Now the precedence of `UMINUS' can be used in specific rules:
-
- exp: ...
- | exp '-' exp
- ...
- | '-' exp %prec UMINUS
-
-
-File: bison.info, Node: Parser States, Next: Reduce/Reduce, Prev: Contextual Precedence, Up: Algorithm
-
-Parser States
-=============
-
- The function `yyparse' is implemented using a finite-state machine.
-The values pushed on the parser stack are not simply token type codes;
-they represent the entire sequence of terminal and nonterminal symbols
-at or near the top of the stack. The current state collects all the
-information about previous input which is relevant to deciding what to
-do next.
-
- Each time a look-ahead token is read, the current parser state
-together with the type of look-ahead token are looked up in a table.
-This table entry can say, "Shift the look-ahead token." In this case,
-it also specifies the new parser state, which is pushed onto the top of
-the parser stack. Or it can say, "Reduce using rule number N." This
-means that a certain number of tokens or groupings are taken off the
-top of the stack, and replaced by one grouping. In other words, that
-number of states are popped from the stack, and one new state is pushed.
-
- There is one other alternative: the table can say that the
-look-ahead token is erroneous in the current state. This causes error
-processing to begin (*note Error Recovery::.).
-
-
-File: bison.info, Node: Reduce/Reduce, Next: Mystery Conflicts, Prev: Parser States, Up: Algorithm
-
-Reduce/Reduce Conflicts
-=======================
-
- A reduce/reduce conflict occurs if there are two or more rules that
-apply to the same sequence of input. This usually indicates a serious
-error in the grammar.
-
- For example, here is an erroneous attempt to define a sequence of
-zero or more `word' groupings.
-
- sequence: /* empty */
- { printf ("empty sequence\n"); }
- | maybeword
- | sequence word
- { printf ("added word %s\n", $2); }
- ;
-
- maybeword: /* empty */
- { printf ("empty maybeword\n"); }
- | word
- { printf ("single word %s\n", $1); }
- ;
-
-The error is an ambiguity: there is more than one way to parse a single
-`word' into a `sequence'. It could be reduced to a `maybeword' and
-then into a `sequence' via the second rule. Alternatively,
-nothing-at-all could be reduced into a `sequence' via the first rule,
-and this could be combined with the `word' using the third rule for
-`sequence'.
-
- There is also more than one way to reduce nothing-at-all into a
-`sequence'. This can be done directly via the first rule, or
-indirectly via `maybeword' and then the second rule.
-
- You might think that this is a distinction without a difference,
-because it does not change whether any particular input is valid or
-not. But it does affect which actions are run. One parsing order runs
-the second rule's action; the other runs the first rule's action and
-the third rule's action. In this example, the output of the program
-changes.
-
- Bison resolves a reduce/reduce conflict by choosing to use the rule
-that appears first in the grammar, but it is very risky to rely on
-this. Every reduce/reduce conflict must be studied and usually
-eliminated. Here is the proper way to define `sequence':
-
- sequence: /* empty */
- { printf ("empty sequence\n"); }
- | sequence word
- { printf ("added word %s\n", $2); }
- ;
-
- Here is another common error that yields a reduce/reduce conflict:
-
- sequence: /* empty */
- | sequence words
- | sequence redirects
- ;
-
- words: /* empty */
- | words word
- ;
-
- redirects:/* empty */
- | redirects redirect
- ;
-
-The intention here is to define a sequence which can contain either
-`word' or `redirect' groupings. The individual definitions of
-`sequence', `words' and `redirects' are error-free, but the three
-together make a subtle ambiguity: even an empty input can be parsed in
-infinitely many ways!
-
- Consider: nothing-at-all could be a `words'. Or it could be two
-`words' in a row, or three, or any number. It could equally well be a
-`redirects', or two, or any number. Or it could be a `words' followed
-by three `redirects' and another `words'. And so on.
-
- Here are two ways to correct these rules. First, to make it a
-single level of sequence:
-
- sequence: /* empty */
- | sequence word
- | sequence redirect
- ;
-
- Second, to prevent either a `words' or a `redirects' from being
-empty:
-
- sequence: /* empty */
- | sequence words
- | sequence redirects
- ;
-
- words: word
- | words word
- ;
-
- redirects:redirect
- | redirects redirect
- ;
-
-
-File: bison.info, Node: Mystery Conflicts, Next: Stack Overflow, Prev: Reduce/Reduce, Up: Algorithm
-
-Mysterious Reduce/Reduce Conflicts
-==================================
-
- Sometimes reduce/reduce conflicts can occur that don't look
-warranted. Here is an example:
-
- %token ID
-
- %%
- def: param_spec return_spec ','
- ;
- param_spec:
- type
- | name_list ':' type
- ;
- return_spec:
- type
- | name ':' type
- ;
- type: ID
- ;
- name: ID
- ;
- name_list:
- name
- | name ',' name_list
- ;
-
- It would seem that this grammar can be parsed with only a single
-token of look-ahead: when a `param_spec' is being read, an `ID' is a
-`name' if a comma or colon follows, or a `type' if another `ID'
-follows. In other words, this grammar is LR(1).
-
- However, Bison, like most parser generators, cannot actually handle
-all LR(1) grammars. In this grammar, two contexts, that after an `ID'
-at the beginning of a `param_spec' and likewise at the beginning of a
-`return_spec', are similar enough that Bison assumes they are the same.
-They appear similar because the same set of rules would be active--the
-rule for reducing to a `name' and that for reducing to a `type'. Bison
-is unable to determine at that stage of processing that the rules would
-require different look-ahead tokens in the two contexts, so it makes a
-single parser state for them both. Combining the two contexts causes a
-conflict later. In parser terminology, this occurrence means that the
-grammar is not LALR(1).
-
- In general, it is better to fix deficiencies than to document them.
-But this particular deficiency is intrinsically hard to fix; parser
-generators that can handle LR(1) grammars are hard to write and tend to
-produce parsers that are very large. In practice, Bison is more useful
-as it is now.
-
- When the problem arises, you can often fix it by identifying the two
-parser states that are being confused, and adding something to make them
-look distinct. In the above example, adding one rule to `return_spec'
-as follows makes the problem go away:
-
- %token BOGUS
- ...
- %%
- ...
- return_spec:
- type
- | name ':' type
- /* This rule is never used. */
- | ID BOGUS
- ;
-
- This corrects the problem because it introduces the possibility of an
-additional active rule in the context after the `ID' at the beginning of
-`return_spec'. This rule is not active in the corresponding context in
-a `param_spec', so the two contexts receive distinct parser states. As
-long as the token `BOGUS' is never generated by `yylex', the added rule
-cannot alter the way actual input is parsed.
-
- In this particular example, there is another way to solve the
-problem: rewrite the rule for `return_spec' to use `ID' directly
-instead of via `name'. This also causes the two confusing contexts to
-have different sets of active rules, because the one for `return_spec'
-activates the altered rule for `return_spec' rather than the one for
-`name'.
-
- param_spec:
- type
- | name_list ':' type
- ;
- return_spec:
- type
- | ID ':' type
- ;
-
-
-File: bison.info, Node: Stack Overflow, Prev: Mystery Conflicts, Up: Algorithm
-
-Stack Overflow, and How to Avoid It
-===================================
-
- The Bison parser stack can overflow if too many tokens are shifted
-and not reduced. When this happens, the parser function `yyparse'
-returns a nonzero value, pausing only to call `yyerror' to report the
-overflow.
-
- By defining the macro `YYMAXDEPTH', you can control how deep the
-parser stack can become before a stack overflow occurs. Define the
-macro with a value that is an integer. This value is the maximum number
-of tokens that can be shifted (and not reduced) before overflow. It
-must be a constant expression whose value is known at compile time.
-
- The stack space allowed is not necessarily allocated. If you
-specify a large value for `YYMAXDEPTH', the parser actually allocates a
-small stack at first, and then makes it bigger by stages as needed.
-This increasing allocation happens automatically and silently.
-Therefore, you do not need to make `YYMAXDEPTH' painfully small merely
-to save space for ordinary inputs that do not need much stack.
-
- The default value of `YYMAXDEPTH', if you do not define it, is 10000.
-
- You can control how much stack is allocated initially by defining the
-macro `YYINITDEPTH'. This value too must be a compile-time constant
-integer. The default is 200.
-
-
-File: bison.info, Node: Error Recovery, Next: Context Dependency, Prev: Algorithm, Up: Top
-
-Error Recovery
-**************
-
- It is not usually acceptable to have a program terminate on a parse
-error. For example, a compiler should recover sufficiently to parse the
-rest of the input file and check it for errors; a calculator should
-accept another expression.
-
- In a simple interactive command parser where each input is one line,
-it may be sufficient to allow `yyparse' to return 1 on error and have
-the caller ignore the rest of the input line when that happens (and
-then call `yyparse' again). But this is inadequate for a compiler,
-because it forgets all the syntactic context leading up to the error.
-A syntax error deep within a function in the compiler input should not
-cause the compiler to treat the following line like the beginning of a
-source file.
-
- You can define how to recover from a syntax error by writing rules to
-recognize the special token `error'. This is a terminal symbol that is
-always defined (you need not declare it) and reserved for error
-handling. The Bison parser generates an `error' token whenever a
-syntax error happens; if you have provided a rule to recognize this
-token in the current context, the parse can continue.
-
- For example:
-
- stmnts: /* empty string */
- | stmnts '\n'
- | stmnts exp '\n'
- | stmnts error '\n'
-
- The fourth rule in this example says that an error followed by a
-newline makes a valid addition to any `stmnts'.
-
- What happens if a syntax error occurs in the middle of an `exp'? The
-error recovery rule, interpreted strictly, applies to the precise
-sequence of a `stmnts', an `error' and a newline. If an error occurs in
-the middle of an `exp', there will probably be some additional tokens
-and subexpressions on the stack after the last `stmnts', and there will
-be tokens to read before the next newline. So the rule is not
-applicable in the ordinary way.
-
- But Bison can force the situation to fit the rule, by discarding
-part of the semantic context and part of the input. First it discards
-states and objects from the stack until it gets back to a state in
-which the `error' token is acceptable. (This means that the
-subexpressions already parsed are discarded, back to the last complete
-`stmnts'.) At this point the `error' token can be shifted. Then, if
-the old look-ahead token is not acceptable to be shifted next, the
-parser reads tokens and discards them until it finds a token which is
-acceptable. In this example, Bison reads and discards input until the
-next newline so that the fourth rule can apply.
-
- The choice of error rules in the grammar is a choice of strategies
-for error recovery. A simple and useful strategy is simply to skip the
-rest of the current input line or current statement if an error is
-detected:
-
- stmnt: error ';' /* on error, skip until ';' is read */
-
- It is also useful to recover to the matching close-delimiter of an
-opening-delimiter that has already been parsed. Otherwise the
-close-delimiter will probably appear to be unmatched, and generate
-another, spurious error message:
-
- primary: '(' expr ')'
- | '(' error ')'
- ...
- ;
-
- Error recovery strategies are necessarily guesses. When they guess
-wrong, one syntax error often leads to another. In the above example,
-the error recovery rule guesses that an error is due to bad input
-within one `stmnt'. Suppose that instead a spurious semicolon is
-inserted in the middle of a valid `stmnt'. After the error recovery
-rule recovers from the first error, another syntax error will be found
-straightaway, since the text following the spurious semicolon is also
-an invalid `stmnt'.
-
- To prevent an outpouring of error messages, the parser will output
-no error message for another syntax error that happens shortly after
-the first; only after three consecutive input tokens have been
-successfully shifted will error messages resume.
-
- Note that rules which accept the `error' token may have actions, just
-as any other rules can.
-
- You can make error messages resume immediately by using the macro
-`yyerrok' in an action. If you do this in the error rule's action, no
-error messages will be suppressed. This macro requires no arguments;
-`yyerrok;' is a valid C statement.
-
- The previous look-ahead token is reanalyzed immediately after an
-error. If this is unacceptable, then the macro `yyclearin' may be used
-to clear this token. Write the statement `yyclearin;' in the error
-rule's action.
-
- For example, suppose that on a parse error, an error handling
-routine is called that advances the input stream to some point where
-parsing should once again commence. The next symbol returned by the
-lexical scanner is probably correct. The previous look-ahead token
-ought to be discarded with `yyclearin;'.
-
- The macro `YYRECOVERING' stands for an expression that has the value
-1 when the parser is recovering from a syntax error, and 0 the rest of
-the time. A value of 1 indicates that error messages are currently
-suppressed for new syntax errors.
-
-
-File: bison.info, Node: Context Dependency, Next: Debugging, Prev: Error Recovery, Up: Top
-
-Handling Context Dependencies
-*****************************
-
- The Bison paradigm is to parse tokens first, then group them into
-larger syntactic units. In many languages, the meaning of a token is
-affected by its context. Although this violates the Bison paradigm,
-certain techniques (known as "kludges") may enable you to write Bison
-parsers for such languages.
-
-* Menu:
-
-* Semantic Tokens:: Token parsing can depend on the semantic context.
-* Lexical Tie-ins:: Token parsing can depend on the syntactic context.
-* Tie-in Recovery:: Lexical tie-ins have implications for how
- error recovery rules must be written.
-
- (Actually, "kludge" means any technique that gets its job done but is
-neither clean nor robust.)
-
-
-File: bison.info, Node: Semantic Tokens, Next: Lexical Tie-ins, Up: Context Dependency
-
-Semantic Info in Token Types
-============================
-
- The C language has a context dependency: the way an identifier is
-used depends on what its current meaning is. For example, consider
-this:
-
- foo (x);
-
- This looks like a function call statement, but if `foo' is a typedef
-name, then this is actually a declaration of `x'. How can a Bison
-parser for C decide how to parse this input?
-
- The method used in GNU C is to have two different token types,
-`IDENTIFIER' and `TYPENAME'. When `yylex' finds an identifier, it
-looks up the current declaration of the identifier in order to decide
-which token type to return: `TYPENAME' if the identifier is declared as
-a typedef, `IDENTIFIER' otherwise.
-
- The grammar rules can then express the context dependency by the
-choice of token type to recognize. `IDENTIFIER' is accepted as an
-expression, but `TYPENAME' is not. `TYPENAME' can start a declaration,
-but `IDENTIFIER' cannot. In contexts where the meaning of the
-identifier is *not* significant, such as in declarations that can
-shadow a typedef name, either `TYPENAME' or `IDENTIFIER' is
-accepted--there is one rule for each of the two token types.
-
- This technique is simple to use if the decision of which kinds of
-identifiers to allow is made at a place close to where the identifier is
-parsed. But in C this is not always so: C allows a declaration to
-redeclare a typedef name provided an explicit type has been specified
-earlier:
-
- typedef int foo, bar, lose;
- static foo (bar); /* redeclare `bar' as static variable */
- static int foo (lose); /* redeclare `foo' as function */
-
- Unfortunately, the name being declared is separated from the
-declaration construct itself by a complicated syntactic structure--the
-"declarator".
-
- As a result, the part of Bison parser for C needs to be duplicated,
-with all the nonterminal names changed: once for parsing a declaration
-in which a typedef name can be redefined, and once for parsing a
-declaration in which that can't be done. Here is a part of the
-duplication, with actions omitted for brevity:
-
- initdcl:
- declarator maybeasm '='
- init
- | declarator maybeasm
- ;
-
- notype_initdcl:
- notype_declarator maybeasm '='
- init
- | notype_declarator maybeasm
- ;
-
-Here `initdcl' can redeclare a typedef name, but `notype_initdcl'
-cannot. The distinction between `declarator' and `notype_declarator'
-is the same sort of thing.
-
- There is some similarity between this technique and a lexical tie-in
-(described next), in that information which alters the lexical analysis
-is changed during parsing by other parts of the program. The
-difference is here the information is global, and is used for other
-purposes in the program. A true lexical tie-in has a special-purpose
-flag controlled by the syntactic context.
-
-
-File: bison.info, Node: Lexical Tie-ins, Next: Tie-in Recovery, Prev: Semantic Tokens, Up: Context Dependency
-
-Lexical Tie-ins
-===============
-
- One way to handle context-dependency is the "lexical tie-in": a flag
-which is set by Bison actions, whose purpose is to alter the way tokens
-are parsed.
-
- For example, suppose we have a language vaguely like C, but with a
-special construct `hex (HEX-EXPR)'. After the keyword `hex' comes an
-expression in parentheses in which all integers are hexadecimal. In
-particular, the token `a1b' must be treated as an integer rather than
-as an identifier if it appears in that context. Here is how you can do
-it:
-
- %{
- int hexflag;
- %}
- %%
- ...
- expr: IDENTIFIER
- | constant
- | HEX '('
- { hexflag = 1; }
- expr ')'
- { hexflag = 0;
- $$ = $4; }
- | expr '+' expr
- { $$ = make_sum ($1, $3); }
- ...
- ;
-
- constant:
- INTEGER
- | STRING
- ;
-
-Here we assume that `yylex' looks at the value of `hexflag'; when it is
-nonzero, all integers are parsed in hexadecimal, and tokens starting
-with letters are parsed as integers if possible.
-
- The declaration of `hexflag' shown in the C declarations section of
-the parser file is needed to make it accessible to the actions (*note
-The C Declarations Section: C Declarations.). You must also write the
-code in `yylex' to obey the flag.
-
-
-File: bison.info, Node: Tie-in Recovery, Prev: Lexical Tie-ins, Up: Context Dependency
-
-Lexical Tie-ins and Error Recovery
-==================================
-
- Lexical tie-ins make strict demands on any error recovery rules you
-have. *Note Error Recovery::.
-
- The reason for this is that the purpose of an error recovery rule is
-to abort the parsing of one construct and resume in some larger
-construct. For example, in C-like languages, a typical error recovery
-rule is to skip tokens until the next semicolon, and then start a new
-statement, like this:
-
- stmt: expr ';'
- | IF '(' expr ')' stmt { ... }
- ...
- error ';'
- { hexflag = 0; }
- ;
-
- If there is a syntax error in the middle of a `hex (EXPR)'
-construct, this error rule will apply, and then the action for the
-completed `hex (EXPR)' will never run. So `hexflag' would remain set
-for the entire rest of the input, or until the next `hex' keyword,
-causing identifiers to be misinterpreted as integers.
-
- To avoid this problem the error recovery rule itself clears
-`hexflag'.
-
- There may also be an error recovery rule that works within
-expressions. For example, there could be a rule which applies within
-parentheses and skips to the close-parenthesis:
-
- expr: ...
- | '(' expr ')'
- { $$ = $2; }
- | '(' error ')'
- ...
-
- If this rule acts within the `hex' construct, it is not going to
-abort that construct (since it applies to an inner level of parentheses
-within the construct). Therefore, it should not clear the flag: the
-rest of the `hex' construct should be parsed with the flag still in
-effect.
-
- What if there is an error recovery rule which might abort out of the
-`hex' construct or might not, depending on circumstances? There is no
-way you can write the action to determine whether a `hex' construct is
-being aborted or not. So if you are using a lexical tie-in, you had
-better make sure your error recovery rules are not of this kind. Each
-rule must be such that you can be sure that it always will, or always
-won't, have to clear the flag.
-
-
-File: bison.info, Node: Debugging, Next: Invocation, Prev: Context Dependency, Up: Top
-
-Debugging Your Parser
-*********************
-
- If a Bison grammar compiles properly but doesn't do what you want
-when it runs, the `yydebug' parser-trace feature can help you figure
-out why.
-
- To enable compilation of trace facilities, you must define the macro
-`YYDEBUG' when you compile the parser. You could use `-DYYDEBUG=1' as
-a compiler option or you could put `#define YYDEBUG 1' in the C
-declarations section of the grammar file (*note The C Declarations
-Section: C Declarations.). Alternatively, use the `-t' option when you
-run Bison (*note Invoking Bison: Invocation.). We always define
-`YYDEBUG' so that debugging is always possible.
-
- The trace facility uses `stderr', so you must add
-`#include <stdio.h>' to the C declarations section unless it is already
-there.
-
- Once you have compiled the program with trace facilities, the way to
-request a trace is to store a nonzero value in the variable `yydebug'.
-You can do this by making the C code do it (in `main', perhaps), or you
-can alter the value with a C debugger.
-
- Each step taken by the parser when `yydebug' is nonzero produces a
-line or two of trace information, written on `stderr'. The trace
-messages tell you these things:
-
- * Each time the parser calls `yylex', what kind of token was read.
-
- * Each time a token is shifted, the depth and complete contents of
- the state stack (*note Parser States::.).
-
- * Each time a rule is reduced, which rule it is, and the complete
- contents of the state stack afterward.
-
- To make sense of this information, it helps to refer to the listing
-file produced by the Bison `-v' option (*note Invoking Bison:
-Invocation.). This file shows the meaning of each state in terms of
-positions in various rules, and also what each state will do with each
-possible input token. As you read the successive trace messages, you
-can see that the parser is functioning according to its specification
-in the listing file. Eventually you will arrive at the place where
-something undesirable happens, and you will see which parts of the
-grammar are to blame.
-
- The parser file is a C program and you can use C debuggers on it,
-but it's not easy to interpret what it is doing. The parser function
-is a finite-state machine interpreter, and aside from the actions it
-executes the same code over and over. Only the values of variables
-show where in the grammar it is working.
-
- The debugging information normally gives the token type of each token
-read, but not its semantic value. You can optionally define a macro
-named `YYPRINT' to provide a way to print the value. If you define
-`YYPRINT', it should take three arguments. The parser will pass a
-standard I/O stream, the numeric code for the token type, and the token
-value (from `yylval').
-
- Here is an example of `YYPRINT' suitable for the multi-function
-calculator (*note Declarations for `mfcalc': Mfcalc Decl.):
-
- #define YYPRINT(file, type, value) yyprint (file, type, value)
-
- static void
- yyprint (file, type, value)
- FILE *file;
- int type;
- YYSTYPE value;
- {
- if (type == VAR)
- fprintf (file, " %s", value.tptr->name);
- else if (type == NUM)
- fprintf (file, " %d", value.val);
- }
-
-
-File: bison.info, Node: Invocation, Next: Table of Symbols, Prev: Debugging, Up: Top
-
-Invoking Bison
-**************
-
- The usual way to invoke Bison is as follows:
-
- bison INFILE
-
- Here INFILE is the grammar file name, which usually ends in `.y'.
-The parser file's name is made by replacing the `.y' with `.tab.c'.
-Thus, the `bison foo.y' filename yields `foo.tab.c', and the `bison
-hack/foo.y' filename yields `hack/foo.tab.c'.
-
-* Menu:
-
-* Bison Options:: All the options described in detail,
- in alphabetical order by short options.
-* Option Cross Key:: Alphabetical list of long options.
-* VMS Invocation:: Bison command syntax on VMS.
-
-
-File: bison.info, Node: Bison Options, Next: Option Cross Key, Up: Invocation
-
-Bison Options
-=============
-
- Bison supports both traditional single-letter options and mnemonic
-long option names. Long option names are indicated with `--' instead of
-`-'. Abbreviations for option names are allowed as long as they are
-unique. When a long option takes an argument, like `--file-prefix',
-connect the option name and the argument with `='.
-
- Here is a list of options that can be used with Bison, alphabetized
-by short option. It is followed by a cross key alphabetized by long
-option.
-
-`-b FILE-PREFIX'
-`--file-prefix=PREFIX'
- Specify a prefix to use for all Bison output file names. The
- names are chosen as if the input file were named `PREFIX.c'.
-
-`-d'
-`--defines'
- Write an extra output file containing macro definitions for the
- token type names defined in the grammar and the semantic value type
- `YYSTYPE', as well as a few `extern' variable declarations.
-
- If the parser output file is named `NAME.c' then this file is
- named `NAME.h'.
-
- This output file is essential if you wish to put the definition of
- `yylex' in a separate source file, because `yylex' needs to be
- able to refer to token type codes and the variable `yylval'.
- *Note Semantic Values of Tokens: Token Values.
-
-`-l'
-`--no-lines'
- Don't put any `#line' preprocessor commands in the parser file.
- Ordinarily Bison puts them in the parser file so that the C
- compiler and debuggers will associate errors with your source
- file, the grammar file. This option causes them to associate
- errors with the parser file, treating it as an independent source
- file in its own right.
-
-`-n'
-`--no-parser'
- Do not include any C code in the parser file; generate tables
- only. The parser file contains just `#define' directives and
- static variable declarations.
-
- This option also tells Bison to write the C code for the grammar
- actions into a file named `FILENAME.act', in the form of a
- brace-surrounded body fit for a `switch' statement.
-
-`-o OUTFILE'
-`--output-file=OUTFILE'
- Specify the name OUTFILE for the parser file.
-
- The other output files' names are constructed from OUTFILE as
- described under the `-v' and `-d' options.
-
-`-p PREFIX'
-`--name-prefix=PREFIX'
- Rename the external symbols used in the parser so that they start
- with PREFIX instead of `yy'. The precise list of symbols renamed
- is `yyparse', `yylex', `yyerror', `yynerrs', `yylval', `yychar'
- and `yydebug'.
-
- For example, if you use `-p c', the names become `cparse', `clex',
- and so on.
-
- *Note Multiple Parsers in the Same Program: Multiple Parsers.
-
-`-r'
-`--raw'
- Pretend that `%raw' was specified. *Note Decl Summary::.
-
-`-t'
-`--debug'
- Output a definition of the macro `YYDEBUG' into the parser file,
- so that the debugging facilities are compiled. *Note Debugging
- Your Parser: Debugging.
-
-`-v'
-`--verbose'
- Write an extra output file containing verbose descriptions of the
- parser states and what is done for each type of look-ahead token in
- that state.
-
- This file also describes all the conflicts, both those resolved by
- operator precedence and the unresolved ones.
-
- The file's name is made by removing `.tab.c' or `.c' from the
- parser output file name, and adding `.output' instead.
-
- Therefore, if the input file is `foo.y', then the parser file is
- called `foo.tab.c' by default. As a consequence, the verbose
- output file is called `foo.output'.
-
-`-V'
-`--version'
- Print the version number of Bison and exit.
-
-`-h'
-`--help'
- Print a summary of the command-line options to Bison and exit.
-
-`-y'
-`--yacc'
-`--fixed-output-files'
- Equivalent to `-o y.tab.c'; the parser output file is called
- `y.tab.c', and the other outputs are called `y.output' and
- `y.tab.h'. The purpose of this option is to imitate Yacc's output
- file name conventions. Thus, the following shell script can
- substitute for Yacc:
-
- bison -y $*
-
-
-File: bison.info, Node: Option Cross Key, Next: VMS Invocation, Prev: Bison Options, Up: Invocation
-
-Option Cross Key
-================
-
- Here is a list of options, alphabetized by long option, to help you
-find the corresponding short option.
-
- --debug -t
- --defines -d
- --file-prefix=PREFIX -b FILE-PREFIX
- --fixed-output-files --yacc -y
- --help -h
- --name-prefix=PREFIX -p NAME-PREFIX
- --no-lines -l
- --no-parser -n
- --output-file=OUTFILE -o OUTFILE
- --raw -r
- --token-table -k
- --verbose -v
- --version -V
-
-
-File: bison.info, Node: VMS Invocation, Prev: Option Cross Key, Up: Invocation
-
-Invoking Bison under VMS
-========================
-
- The command line syntax for Bison on VMS is a variant of the usual
-Bison command syntax--adapted to fit VMS conventions.
-
- To find the VMS equivalent for any Bison option, start with the long
-option, and substitute a `/' for the leading `--', and substitute a `_'
-for each `-' in the name of the long option. For example, the
-following invocation under VMS:
-
- bison /debug/name_prefix=bar foo.y
-
-is equivalent to the following command under POSIX.
-
- bison --debug --name-prefix=bar foo.y
-
- The VMS file system does not permit filenames such as `foo.tab.c'.
-In the above example, the output file would instead be named
-`foo_tab.c'.
-
-
-File: bison.info, Node: Table of Symbols, Next: Glossary, Prev: Invocation, Up: Top
-
-Bison Symbols
-*************
-
-`error'
- A token name reserved for error recovery. This token may be used
- in grammar rules so as to allow the Bison parser to recognize an
- error in the grammar without halting the process. In effect, a
- sentence containing an error may be recognized as valid. On a
- parse error, the token `error' becomes the current look-ahead
- token. Actions corresponding to `error' are then executed, and
- the look-ahead token is reset to the token that originally caused
- the violation. *Note Error Recovery::.
-
-`YYABORT'
- Macro to pretend that an unrecoverable syntax error has occurred,
- by making `yyparse' return 1 immediately. The error reporting
- function `yyerror' is not called. *Note The Parser Function
- `yyparse': Parser Function.
-
-`YYACCEPT'
- Macro to pretend that a complete utterance of the language has been
- read, by making `yyparse' return 0 immediately. *Note The Parser
- Function `yyparse': Parser Function.
-
-`YYBACKUP'
- Macro to discard a value from the parser stack and fake a
- look-ahead token. *Note Special Features for Use in Actions:
- Action Features.
-
-`YYERROR'
- Macro to pretend that a syntax error has just been detected: call
- `yyerror' and then perform normal error recovery if possible
- (*note Error Recovery::.), or (if recovery is impossible) make
- `yyparse' return 1. *Note Error Recovery::.
-
-`YYERROR_VERBOSE'
- Macro that you define with `#define' in the Bison declarations
- section to request verbose, specific error message strings when
- `yyerror' is called.
-
-`YYINITDEPTH'
- Macro for specifying the initial size of the parser stack. *Note
- Stack Overflow::.
-
-`YYLEX_PARAM'
- Macro for specifying an extra argument (or list of extra
- arguments) for `yyparse' to pass to `yylex'. *Note Calling
- Conventions for Pure Parsers: Pure Calling.
-
-`YYLTYPE'
- Macro for the data type of `yylloc'; a structure with four
- members. *Note Textual Positions of Tokens: Token Positions.
-
-`yyltype'
- Default value for YYLTYPE.
-
-`YYMAXDEPTH'
- Macro for specifying the maximum size of the parser stack. *Note
- Stack Overflow::.
-
-`YYPARSE_PARAM'
- Macro for specifying the name of a parameter that `yyparse' should
- accept. *Note Calling Conventions for Pure Parsers: Pure Calling.
-
-`YYRECOVERING'
- Macro whose value indicates whether the parser is recovering from a
- syntax error. *Note Special Features for Use in Actions: Action
- Features.
-
-`YYSTYPE'
- Macro for the data type of semantic values; `int' by default.
- *Note Data Types of Semantic Values: Value Type.
-
-`yychar'
- External integer variable that contains the integer value of the
- current look-ahead token. (In a pure parser, it is a local
- variable within `yyparse'.) Error-recovery rule actions may
- examine this variable. *Note Special Features for Use in Actions:
- Action Features.
-
-`yyclearin'
- Macro used in error-recovery rule actions. It clears the previous
- look-ahead token. *Note Error Recovery::.
-
-`yydebug'
- External integer variable set to zero by default. If `yydebug' is
- given a nonzero value, the parser will output information on input
- symbols and parser action. *Note Debugging Your Parser: Debugging.
-
-`yyerrok'
- Macro to cause parser to recover immediately to its normal mode
- after a parse error. *Note Error Recovery::.
-
-`yyerror'
- User-supplied function to be called by `yyparse' on error. The
- function receives one argument, a pointer to a character string
- containing an error message. *Note The Error Reporting Function
- `yyerror': Error Reporting.
-
-`yylex'
- User-supplied lexical analyzer function, called with no arguments
- to get the next token. *Note The Lexical Analyzer Function
- `yylex': Lexical.
-
-`yylval'
- External variable in which `yylex' should place the semantic value
- associated with a token. (In a pure parser, it is a local
- variable within `yyparse', and its address is passed to `yylex'.)
- *Note Semantic Values of Tokens: Token Values.
-
-`yylloc'
- External variable in which `yylex' should place the line and
- column numbers associated with a token. (In a pure parser, it is a
- local variable within `yyparse', and its address is passed to
- `yylex'.) You can ignore this variable if you don't use the `@'
- feature in the grammar actions. *Note Textual Positions of
- Tokens: Token Positions.
-
-`yynerrs'
- Global variable which Bison increments each time there is a parse
- error. (In a pure parser, it is a local variable within
- `yyparse'.) *Note The Error Reporting Function `yyerror': Error
- Reporting.
-
-`yyparse'
- The parser function produced by Bison; call this function to start
- parsing. *Note The Parser Function `yyparse': Parser Function.
-
-`%left'
- Bison declaration to assign left associativity to token(s). *Note
- Operator Precedence: Precedence Decl.
-
-`%no_lines'
- Bison declaration to avoid generating `#line' directives in the
- parser file. *Note Decl Summary::.
-
-`%nonassoc'
- Bison declaration to assign nonassociativity to token(s). *Note
- Operator Precedence: Precedence Decl.
-
-`%prec'
- Bison declaration to assign a precedence to a specific rule.
- *Note Context-Dependent Precedence: Contextual Precedence.
-
-`%pure_parser'
- Bison declaration to request a pure (reentrant) parser. *Note A
- Pure (Reentrant) Parser: Pure Decl.
-
-`%raw'
- Bison declaration to use Bison internal token code numbers in token
- tables instead of the usual Yacc-compatible token code numbers.
- *Note Decl Summary::.
-
-`%right'
- Bison declaration to assign right associativity to token(s).
- *Note Operator Precedence: Precedence Decl.
-
-`%start'
- Bison declaration to specify the start symbol. *Note The
- Start-Symbol: Start Decl.
-
-`%token'
- Bison declaration to declare token(s) without specifying
- precedence. *Note Token Type Names: Token Decl.
-
-`%token_table'
- Bison declaration to include a token name table in the parser file.
- *Note Decl Summary::.
-
-`%type'
- Bison declaration to declare nonterminals. *Note Nonterminal
- Symbols: Type Decl.
-
-`%union'
- Bison declaration to specify several possible data types for
- semantic values. *Note The Collection of Value Types: Union Decl.
-
- These are the punctuation and delimiters used in Bison input:
-
-`%%'
- Delimiter used to separate the grammar rule section from the Bison
- declarations section or the additional C code section. *Note The
- Overall Layout of a Bison Grammar: Grammar Layout.
-
-`%{ %}'
- All code listed between `%{' and `%}' is copied directly to the
- output file uninterpreted. Such code forms the "C declarations"
- section of the input file. *Note Outline of a Bison Grammar:
- Grammar Outline.
-
-`/*...*/'
- Comment delimiters, as in C.
-
-`:'
- Separates a rule's result from its components. *Note Syntax of
- Grammar Rules: Rules.
-
-`;'
- Terminates a rule. *Note Syntax of Grammar Rules: Rules.
-
-`|'
- Separates alternate rules for the same result nonterminal. *Note
- Syntax of Grammar Rules: Rules.
-
-
-File: bison.info, Node: Glossary, Next: Index, Prev: Table of Symbols, Up: Top
-
-Glossary
-********
-
-Backus-Naur Form (BNF)
- Formal method of specifying context-free grammars. BNF was first
- used in the `ALGOL-60' report, 1963. *Note Languages and
- Context-Free Grammars: Language and Grammar.
-
-Context-free grammars
- Grammars specified as rules that can be applied regardless of
- context. Thus, if there is a rule which says that an integer can
- be used as an expression, integers are allowed *anywhere* an
- expression is permitted. *Note Languages and Context-Free
- Grammars: Language and Grammar.
-
-Dynamic allocation
- Allocation of memory that occurs during execution, rather than at
- compile time or on entry to a function.
-
-Empty string
- Analogous to the empty set in set theory, the empty string is a
- character string of length zero.
-
-Finite-state stack machine
- A "machine" that has discrete states in which it is said to exist
- at each instant in time. As input to the machine is processed, the
- machine moves from state to state as specified by the logic of the
- machine. In the case of the parser, the input is the language
- being parsed, and the states correspond to various stages in the
- grammar rules. *Note The Bison Parser Algorithm: Algorithm.
-
-Grouping
- A language construct that is (in general) grammatically divisible;
- for example, `expression' or `declaration' in C. *Note Languages
- and Context-Free Grammars: Language and Grammar.
-
-Infix operator
- An arithmetic operator that is placed between the operands on
- which it performs some operation.
-
-Input stream
- A continuous flow of data between devices or programs.
-
-Language construct
- One of the typical usage schemas of the language. For example,
- one of the constructs of the C language is the `if' statement.
- *Note Languages and Context-Free Grammars: Language and Grammar.
-
-Left associativity
- Operators having left associativity are analyzed from left to
- right: `a+b+c' first computes `a+b' and then combines with `c'.
- *Note Operator Precedence: Precedence.
-
-Left recursion
- A rule whose result symbol is also its first component symbol; for
- example, `expseq1 : expseq1 ',' exp;'. *Note Recursive Rules:
- Recursion.
-
-Left-to-right parsing
- Parsing a sentence of a language by analyzing it token by token
- from left to right. *Note The Bison Parser Algorithm: Algorithm.
-
-Lexical analyzer (scanner)
- A function that reads an input stream and returns tokens one by
- one. *Note The Lexical Analyzer Function `yylex': Lexical.
-
-Lexical tie-in
- A flag, set by actions in the grammar rules, which alters the way
- tokens are parsed. *Note Lexical Tie-ins::.
-
-Literal string token
- A token which constists of two or more fixed characters. *Note
- Symbols::.
-
-Look-ahead token
- A token already read but not yet shifted. *Note Look-Ahead
- Tokens: Look-Ahead.
-
-LALR(1)
- The class of context-free grammars that Bison (like most other
- parser generators) can handle; a subset of LR(1). *Note
- Mysterious Reduce/Reduce Conflicts: Mystery Conflicts.
-
-LR(1)
- The class of context-free grammars in which at most one token of
- look-ahead is needed to disambiguate the parsing of any piece of
- input.
-
-Nonterminal symbol
- A grammar symbol standing for a grammatical construct that can be
- expressed through rules in terms of smaller constructs; in other
- words, a construct that is not a token. *Note Symbols::.
-
-Parse error
- An error encountered during parsing of an input stream due to
- invalid syntax. *Note Error Recovery::.
-
-Parser
- A function that recognizes valid sentences of a language by
- analyzing the syntax structure of a set of tokens passed to it
- from a lexical analyzer.
-
-Postfix operator
- An arithmetic operator that is placed after the operands upon
- which it performs some operation.
-
-Reduction
- Replacing a string of nonterminals and/or terminals with a single
- nonterminal, according to a grammar rule. *Note The Bison Parser
- Algorithm: Algorithm.
-
-Reentrant
- A reentrant subprogram is a subprogram which can be in invoked any
- number of times in parallel, without interference between the
- various invocations. *Note A Pure (Reentrant) Parser: Pure Decl.
-
-Reverse polish notation
- A language in which all operators are postfix operators.
-
-Right recursion
- A rule whose result symbol is also its last component symbol; for
- example, `expseq1: exp ',' expseq1;'. *Note Recursive Rules:
- Recursion.
-
-Semantics
- In computer languages, the semantics are specified by the actions
- taken for each instance of the language, i.e., the meaning of each
- statement. *Note Defining Language Semantics: Semantics.
-
-Shift
- A parser is said to shift when it makes the choice of analyzing
- further input from the stream rather than reducing immediately some
- already-recognized rule. *Note The Bison Parser Algorithm:
- Algorithm.
-
-Single-character literal
- A single character that is recognized and interpreted as is.
- *Note From Formal Rules to Bison Input: Grammar in Bison.
-
-Start symbol
- The nonterminal symbol that stands for a complete valid utterance
- in the language being parsed. The start symbol is usually listed
- as the first nonterminal symbol in a language specification.
- *Note The Start-Symbol: Start Decl.
-
-Symbol table
- A data structure where symbol names and associated data are stored
- during parsing to allow for recognition and use of existing
- information in repeated uses of a symbol. *Note Multi-function
- Calc::.
-
-Token
- A basic, grammatically indivisible unit of a language. The symbol
- that describes a token in the grammar is a terminal symbol. The
- input of the Bison parser is a stream of tokens which comes from
- the lexical analyzer. *Note Symbols::.
-
-Terminal symbol
- A grammar symbol that has no rules in the grammar and therefore is
- grammatically indivisible. The piece of text it represents is a
- token. *Note Languages and Context-Free Grammars: Language and
- Grammar.
-
diff -rup --new-file baseline/fsf/bison/bison.info-5 amiga/fsf/bison/bison.info-5
--- baseline/fsf/bison/bison.info-5 Sat Feb 17 09:46:08 1996
+++ amiga/fsf/bison/bison.info-5 Wed Dec 31 17:00:00 1969
@@ -1,234 +0,0 @@
-This is Info file bison.info, produced by Makeinfo-1.64 from the input
-file ./bison.texinfo.
-
- This file documents the Bison parser generator.
-
- Copyright (C) 1988, 89, 90, 91, 92, 93, 1995 Free Software
-Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the sections entitled "GNU General Public License" and "Conditions
-for Using Bison" are included exactly as in the original, and provided
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the sections entitled "GNU General Public
-License", "Conditions for Using Bison" and this permission notice may be
-included in translations approved by the Free Software Foundation
-instead of in the original English.
-
-
-File: bison.info, Node: Index, Prev: Glossary, Up: Top
-
-Index
-*****
-
-* Menu:
-
-* $$: Actions.
-* $N: Actions.
-* %expect: Expect Decl.
-* %left: Using Precedence.
-* %nonassoc: Using Precedence.
-* %prec: Contextual Precedence.
-* %pure_parser: Pure Decl.
-* %right: Using Precedence.
-* %start: Start Decl.
-* %token: Token Decl.
-* %type: Type Decl.
-* %union: Union Decl.
-* @N: Action Features.
-* calc: Infix Calc.
-* else, dangling: Shift/Reduce.
-* mfcalc: Multi-function Calc.
-* rpcalc: RPN Calc.
-* action: Actions.
-* action data types: Action Types.
-* action features summary: Action Features.
-* actions in mid-rule: Mid-Rule Actions.
-* actions, semantic: Semantic Actions.
-* additional C code section: C Code.
-* algorithm of parser: Algorithm.
-* associativity: Why Precedence.
-* Backus-Naur form: Language and Grammar.
-* Bison declaration summary: Decl Summary.
-* Bison declarations: Declarations.
-* Bison declarations (introduction): Bison Declarations.
-* Bison grammar: Grammar in Bison.
-* Bison invocation: Invocation.
-* Bison parser: Bison Parser.
-* Bison parser algorithm: Algorithm.
-* Bison symbols, table of: Table of Symbols.
-* Bison utility: Bison Parser.
-* BNF: Language and Grammar.
-* C code, section for additional: C Code.
-* C declarations section: C Declarations.
-* C-language interface: Interface.
-* calculator, infix notation: Infix Calc.
-* calculator, multi-function: Multi-function Calc.
-* calculator, simple: RPN Calc.
-* character token: Symbols.
-* compiling the parser: Rpcalc Compile.
-* conflicts: Shift/Reduce.
-* conflicts, reduce/reduce: Reduce/Reduce.
-* conflicts, suppressing warnings of: Expect Decl.
-* context-dependent precedence: Contextual Precedence.
-* context-free grammar: Language and Grammar.
-* controlling function: Rpcalc Main.
-* dangling else: Shift/Reduce.
-* data types in actions: Action Types.
-* data types of semantic values: Value Type.
-* debugging: Debugging.
-* declaration summary: Decl Summary.
-* declarations, Bison: Declarations.
-* declarations, Bison (introduction): Bison Declarations.
-* declarations, C: C Declarations.
-* declaring literal string tokens: Token Decl.
-* declaring operator precedence: Precedence Decl.
-* declaring the start symbol: Start Decl.
-* declaring token type names: Token Decl.
-* declaring value types: Union Decl.
-* declaring value types, nonterminals: Type Decl.
-* default action: Actions.
-* default data type: Value Type.
-* default stack limit: Stack Overflow.
-* default start symbol: Start Decl.
-* defining language semantics: Semantics.
-* error: Error Recovery.
-* error recovery: Error Recovery.
-* error recovery, simple: Simple Error Recovery.
-* error reporting function: Error Reporting.
-* error reporting routine: Rpcalc Error.
-* examples, simple: Examples.
-* exercises: Exercises.
-* file format: Grammar Layout.
-* finite-state machine: Parser States.
-* formal grammar: Grammar in Bison.
-* format of grammar file: Grammar Layout.
-* glossary: Glossary.
-* grammar file: Grammar Layout.
-* grammar rule syntax: Rules.
-* grammar rules section: Grammar Rules.
-* grammar, Bison: Grammar in Bison.
-* grammar, context-free: Language and Grammar.
-* grouping, syntactic: Language and Grammar.
-* infix notation calculator: Infix Calc.
-* interface: Interface.
-* introduction: Introduction.
-* invoking Bison: Invocation.
-* invoking Bison under VMS: VMS Invocation.
-* LALR(1): Mystery Conflicts.
-* language semantics, defining: Semantics.
-* layout of Bison grammar: Grammar Layout.
-* left recursion: Recursion.
-* lexical analyzer: Lexical.
-* lexical analyzer, purpose: Bison Parser.
-* lexical analyzer, writing: Rpcalc Lexer.
-* lexical tie-in: Lexical Tie-ins.
-* literal string token: Symbols.
-* literal token: Symbols.
-* look-ahead token: Look-Ahead.
-* LR(1): Mystery Conflicts.
-* main function in simple example: Rpcalc Main.
-* mid-rule actions: Mid-Rule Actions.
-* multi-character literal: Symbols.
-* multi-function calculator: Multi-function Calc.
-* mutual recursion: Recursion.
-* nonterminal symbol: Symbols.
-* operator precedence: Precedence.
-* operator precedence, declaring: Precedence Decl.
-* options for invoking Bison: Invocation.
-* overflow of parser stack: Stack Overflow.
-* parse error: Error Reporting.
-* parser: Bison Parser.
-* parser stack: Algorithm.
-* parser stack overflow: Stack Overflow.
-* parser state: Parser States.
-* polish notation calculator: RPN Calc.
-* precedence declarations: Precedence Decl.
-* precedence of operators: Precedence.
-* precedence, context-dependent: Contextual Precedence.
-* precedence, unary operator: Contextual Precedence.
-* preventing warnings about conflicts: Expect Decl.
-* pure parser: Pure Decl.
-* recovery from errors: Error Recovery.
-* recursive rule: Recursion.
-* reduce/reduce conflict: Reduce/Reduce.
-* reduction: Algorithm.
-* reentrant parser: Pure Decl.
-* reverse polish notation: RPN Calc.
-* right recursion: Recursion.
-* rule syntax: Rules.
-* rules section for grammar: Grammar Rules.
-* running Bison (introduction): Rpcalc Gen.
-* semantic actions: Semantic Actions.
-* semantic value: Semantic Values.
-* semantic value type: Value Type.
-* shift/reduce conflicts: Shift/Reduce.
-* shifting: Algorithm.
-* simple examples: Examples.
-* single-character literal: Symbols.
-* stack overflow: Stack Overflow.
-* stack, parser: Algorithm.
-* stages in using Bison: Stages.
-* start symbol: Language and Grammar.
-* start symbol, declaring: Start Decl.
-* state (of parser): Parser States.
-* string token: Symbols.
-* summary, action features: Action Features.
-* summary, Bison declaration: Decl Summary.
-* suppressing conflict warnings: Expect Decl.
-* symbol: Symbols.
-* symbol table example: Mfcalc Symtab.
-* symbols (abstract): Language and Grammar.
-* symbols in Bison, table of: Table of Symbols.
-* syntactic grouping: Language and Grammar.
-* syntax error: Error Reporting.
-* syntax of grammar rules: Rules.
-* terminal symbol: Symbols.
-* token: Language and Grammar.
-* token type: Symbols.
-* token type names, declaring: Token Decl.
-* tracing the parser: Debugging.
-* unary operator precedence: Contextual Precedence.
-* using Bison: Stages.
-* value type, semantic: Value Type.
-* value types, declaring: Union Decl.
-* value types, nonterminals, declaring: Type Decl.
-* value, semantic: Semantic Values.
-* VMS: VMS Invocation.
-* warnings, preventing: Expect Decl.
-* writing a lexical analyzer: Rpcalc Lexer.
-* YYABORT: Parser Function.
-* YYACCEPT: Parser Function.
-* YYBACKUP: Action Features.
-* yychar: Look-Ahead.
-* yyclearin: Error Recovery.
-* YYDEBUG: Debugging.
-* YYEMPTY: Action Features.
-* yyerrok: Error Recovery.
-* YYERROR: Action Features.
-* yyerror: Error Reporting.
-* YYERROR_VERBOSE: Error Reporting.
-* YYINITDEPTH: Stack Overflow.
-* yylex: Lexical.
-* YYLEX_PARAM: Pure Calling.
-* yylloc: Token Positions.
-* YYLTYPE: Token Positions.
-* yylval: Token Values.
-* YYMAXDEPTH: Stack Overflow.
-* yynerrs: Error Reporting.
-* yyparse: Parser Function.
-* YYPARSE_PARAM: Pure Calling.
-* YYPRINT: Debugging.
-* YYRECOVERING: Error Recovery.
-* |: Rules.
-
-
diff -rup --new-file baseline/fsf/bison/configure amiga/fsf/bison/configure
--- baseline/fsf/bison/configure Thu Dec 28 13:08:14 1995
+++ amiga/fsf/bison/configure Mon Sep 30 22:37:48 1996
@@ -1,8 +1,8 @@
#! /bin/sh
# Guess values for system-dependent variables and create Makefiles.
-# Generated automatically using autoconf version 2.7
-# Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
+# Generated automatically using autoconf version 2.10
+# Copyright (C) 1992, 93, 94, 95, 96 Free Software Foundation, Inc.
#
# This configure script is free software; the Free Software Foundation
# gives unlimited permission to copy, distribute and modify it.
@@ -44,6 +44,9 @@ libdir='${exec_prefix}/lib'
includedir='${prefix}/include'
oldincludedir='/usr/include'
infodir='${prefix}/info'
+guidedir='${prefix}/guide'
+psdir='${prefix}/ps'
+dvidir='${prefix}/dvi'
mandir='${prefix}/man'
# Initialize some other variables.
@@ -158,6 +161,9 @@ Directory and file names:
--includedir=DIR C header files in DIR [PREFIX/include]
--oldincludedir=DIR C header files for non-gcc in DIR [/usr/include]
--infodir=DIR info documentation in DIR [PREFIX/info]
+ --guidedir=DIR Amigaguide documentation in DIR [PREFIX/guide]
+ --psdir=DIR postscript documentation in DIR [PREFIX/ps]
+ --dvidir=DIR TeX dvi documentation in DIR [PREFIX/dvi]
--mandir=DIR man documentation in DIR [PREFIX/man]
--srcdir=DIR find the sources in DIR [configure dir or ..]
--program-prefix=PREFIX prepend PREFIX to installed program names
@@ -200,6 +206,18 @@ EOF
-infodir=* | --infodir=* | --infodi=* | --infod=* | --info=* | --inf=*)
infodir="$ac_optarg" ;;
+ -guidedir | --guidedir | --guidedi | --guided | --guide | --gui)
+ ac_prev=guidedir ;;
+ -guidedir=* | --guidedir=* | --guidedi=* | --guided=* | --guide=* |--gui=*)+ guidedir="$ac_optarg" ;;
+
+ -psdir | --psdir | --psdi | --psd | --ps)
+ ac_prev=psdir ;;
+ -psdir=* | --psdir=* | --psdi=* | --psd=* | --ps=*)+ psdir="$ac_optarg" ;;
+
+ -dvidir | --dvidir | --dvidi | --dvid | --dvi | --dv)
+ ac_prev=dvidir ;;
+ -dvidir=* | --dvidir=* | --dvidi=* | --dvid=* | --dvi=* |--dv=*)+ dvidir="$ac_optarg" ;;
+
-libdir | --libdir | --libdi | --libd)
ac_prev=libdir ;;
-libdir=* | --libdir=* | --libdi=* | --libd=*)
@@ -330,7 +348,7 @@ EOF
verbose=yes ;;
-version | --version | --versio | --versi | --vers)
- echo "configure generated by autoconf version 2.7"
+ echo "configure generated by autoconf version 2.10"
exit 0 ;;
-with-* | --with-*)
@@ -495,12 +513,9 @@ fi
ac_ext=c
# CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
-ac_cpp='echo $CPP $CPPFLAGS 1>&5;
-$CPP $CPPFLAGS'
-ac_compile='echo ${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5;
-${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5 2>&5'
-ac_link='echo ${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5;
-${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5 2>&5'
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5'
+ac_link='${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5'
if (echo "testing\c"; echo 1,2,3) | grep c >/dev/null; then
# Stardent Vistra SVR4 grep lacks -e, says ghazi@caip.rutgers.edu.
@@ -534,7 +549,6 @@ else
fi
done
IFS="$ac_save_ifs"
- test -z "$ac_cv_prog_CC" && ac_cv_prog_CC="cc"
fi
fi
CC="$ac_cv_prog_CC"
@@ -544,6 +558,55 @@ else
echo "$ac_t""no" 1>&6
fi
+if test -z "$CC"; then
+ # Extract the first word of "cc", so it can be a program name with args.
+set dummy cc; ac_word=$2
+echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
+if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
+ echo $ac_n "(cached) $ac_c" 1>&6
+else
+ if test -n "$CC"; then
+ ac_cv_prog_CC="$CC" # Let the user override the test.
+else
+ IFS="${IFS= }"; ac_save_ifs="$IFS"; IFS="${IFS}:"
+ ac_prog_rejected=no
+ for ac_dir in $PATH; do
+ test -z "$ac_dir" && ac_dir=.
+ if test -f $ac_dir/$ac_word; then
+ if test "$ac_dir/$ac_word" = "/usr/ucb/cc"; then
+ ac_prog_rejected=yes
+ continue
+ fi
+ ac_cv_prog_CC="cc"
+ break
+ fi
+ done
+ IFS="$ac_save_ifs"
+if test $ac_prog_rejected = yes; then
+ # We found a bogon in the path, so make sure we never use it.
+ set dummy $ac_cv_prog_CC
+ shift
+ if test $# -gt 0; then
+ # We chose a different compiler from the bogus one.
+ # However, it has the same basename, so the bogon will be chosen
+ # first if we set CC to just the basename; use the full file name.
+ shift
+ set dummy "$ac_dir/$ac_word" "$@"
+ shift
+ ac_cv_prog_CC="$@"
+ fi
+fi
+fi
+fi
+CC="$ac_cv_prog_CC"
+if test -n "$CC"; then
+ echo "$ac_t""$CC" 1>&6
+else
+ echo "$ac_t""no" 1>&6
+fi
+
+ test -z "$CC" && { echo "configure: error: no acceptable cc found in \$PATH" 1>&2; exit 1; }
+fi
echo $ac_n "checking whether we are using GNU C""... $ac_c" 1>&6
if eval "test \"`echo '$''{'ac_cv_prog_gcc'+set}'`\" = set"; then
@@ -554,7 +617,7 @@ else
yes;
#endif
EOF
-if ${CC-cc} -E conftest.c 2>&5 | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:621: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
ac_cv_prog_gcc=yes
else
ac_cv_prog_gcc=no
@@ -581,9 +644,9 @@ fi
echo "$ac_t""$ac_cv_prog_gcc_g" 1>&6
if test $ac_cv_prog_gcc_g = yes; then
- CFLAGS="-g -O"
+ CFLAGS="-g -O2"
else
- CFLAGS="-O"
+ CFLAGS="-O2"
fi
fi
else
@@ -617,6 +680,7 @@ ac_configure=$ac_aux_dir/configure # Thi
# SunOS /usr/etc/install
# IRIX /sbin/install
# AIX /bin/install
+# AmigaOS /c/install
# AFS /usr/afsws/bin/install, which mishandles nonexistent args
# SVR4 /usr/ucb/install, which tries to use the nonexistent group "staff"
# ./install, which can be erroneously created by make from ./install.sh.
@@ -629,7 +693,7 @@ else
for ac_dir in $PATH; do
# Account for people who put trailing slashes in PATH elements.
case "$ac_dir/" in
- /|./|.//|/etc/*|/usr/sbin/*|/usr/etc/*|/sbin/*|/usr/afsws/bin/*|/usr/ucb/*) ;;
+ /|./|.//|/etc/*|/c/*|/usr/sbin/*|/usr/etc/*|/sbin/*|/usr/afsws/bin/*|/usr/ucb/*) ;;
*)
# OSF1 and SCO ODT 3.0 have their own names for install.
for ac_prog in ginstall installbsd scoinst install; do
@@ -685,12 +749,13 @@ else
# On the NeXT, cc -E runs the code through the compiler's parser,
# not just through cpp.
cat > conftest.$ac_ext <<EOF
-#line 689 "configure"
+#line 753 "configure"
#include "confdefs.h"
#include <assert.h>
Syntax Error
EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:759: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
ac_err=`grep -v '^ *+' conftest.out`
if test -z "$ac_err"; then
:
@@ -699,12 +764,13 @@ else
rm -rf conftest*
CPP="${CC-cc} -E -traditional-cpp"
cat > conftest.$ac_ext <<EOF
-#line 703 "configure"
+#line 768 "configure"
#include "confdefs.h"
#include <assert.h>
Syntax Error
EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:774: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
ac_err=`grep -v '^ *+' conftest.out`
if test -z "$ac_err"; then
:
@@ -730,11 +796,12 @@ if eval "test \"`echo '$''{'ac_cv_header
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 734 "configure"
+#line 800 "configure"
#include "confdefs.h"
#include <minix/config.h>
EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:805: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
ac_err=`grep -v '^ *+' conftest.out`
if test -z "$ac_err"; then
rm -rf conftest*
@@ -799,11 +866,11 @@ else
ac_cv_c_cross=yes
else
cat > conftest.$ac_ext <<EOF
-#line 803 "configure"
+#line 870 "configure"
#include "confdefs.h"
main(){return(0);}
EOF
-eval $ac_link
+{ (eval echo configure:874: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
if test -s conftest && (./conftest; exit) 2>/dev/null; then
ac_cv_c_cross=no
else
@@ -821,14 +888,15 @@ if eval "test \"`echo '$''{'ac_cv_header
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 825 "configure"
+#line 892 "configure"
#include "confdefs.h"
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <float.h>
EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:900: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
ac_err=`grep -v '^ *+' conftest.out`
if test -z "$ac_err"; then
rm -rf conftest*
@@ -843,7 +911,7 @@ rm -f conftest*
if test $ac_cv_header_stdc = yes; then
# SunOS 4.x string.h does not declare mem*, contrary to ANSI.
cat > conftest.$ac_ext <<EOF
-#line 847 "configure"
+#line 915 "configure"
#include "confdefs.h"
#include <string.h>
EOF
@@ -861,7 +929,7 @@ fi
if test $ac_cv_header_stdc = yes; then
# ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
cat > conftest.$ac_ext <<EOF
-#line 865 "configure"
+#line 933 "configure"
#include "confdefs.h"
#include <stdlib.h>
EOF
@@ -882,7 +950,7 @@ if test "$cross_compiling" = yes; then
:
else
cat > conftest.$ac_ext <<EOF
-#line 886 "configure"
+#line 954 "configure"
#include "confdefs.h"
#include <ctype.h>
#define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -893,7 +961,7 @@ if (XOR (islower (i), ISLOWER (i)) || to
exit (0); }
EOF
-eval $ac_link
+{ (eval echo configure:965: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
if test -s conftest && (./conftest; exit) 2>/dev/null; then
:
else
@@ -920,11 +988,12 @@ if eval "test \"`echo '$''{'ac_cv_header
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 924 "configure"
+#line 992 "configure"
#include "confdefs.h"
#include <$ac_hdr>
EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:997: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
ac_err=`grep -v '^ *+' conftest.out`
if test -z "$ac_err"; then
rm -rf conftest*
@@ -954,7 +1023,7 @@ if eval "test \"`echo '$''{'ac_cv_c_cons
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 958 "configure"
+#line 1027 "configure"
#include "confdefs.h"
int main() { return 0; }
@@ -1004,7 +1073,7 @@ ccp = (char const *const *) p;
; return 0; }
EOF
-if eval $ac_compile; then
+if { (eval echo configure:1077: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
rm -rf conftest*
ac_cv_c_const=yes
else
@@ -1031,15 +1100,15 @@ if eval "test \"`echo '$''{'ac_cv_header
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 1035 "configure"
+#line 1104 "configure"
#include "confdefs.h"
#include <alloca.h>
-int main() { return 0; }
+int main() { t(); return 0; }
int t() {
char *p = alloca(2 * sizeof(int));
; return 0; }
EOF
-if eval $ac_link; then
+if { (eval echo configure:1112: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
rm -rf conftest*
ac_cv_header_alloca_h=yes
else
@@ -1063,7 +1132,7 @@ if eval "test \"`echo '$''{'ac_cv_func_a
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 1067 "configure"
+#line 1136 "configure"
#include "confdefs.h"
#ifdef __GNUC__
@@ -1082,12 +1151,12 @@ char *alloca ();
# endif
#endif
-int main() { return 0; }
+int main() { t(); return 0; }
int t() {
char *p = (char *) alloca(1);
; return 0; }
EOF
-if eval $ac_link; then
+if { (eval echo configure:1160: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
rm -rf conftest*
ac_cv_func_alloca=yes
else
@@ -1122,7 +1191,7 @@ if eval "test \"`echo '$''{'ac_cv_os_cra
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 1126 "configure"
+#line 1195 "configure"
#include "confdefs.h"
#if defined(CRAY) && ! defined(CRAY2)
webecray
@@ -1151,15 +1220,17 @@ if eval "test \"`echo '$''{'ac_cv_func_$
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 1155 "configure"
+#line 1224 "configure"
#include "confdefs.h"
/* System header to define __stub macros and hopefully few prototypes,
which can conflict with char $ac_func(); below. */
#include <assert.h>
/* Override any gcc2 internal prototype to avoid an error. */
+/* We use char because int might match the return type of a gcc2
+ builtin and then its argument prototype would still apply. */
char $ac_func();
-int main() { return 0; }
+int main() { t(); return 0; }
int t() {
/* The GNU C library defines this for functions which it implements
@@ -1173,7 +1244,7 @@ $ac_func();
; return 0; }
EOF
-if eval $ac_link; then
+if { (eval echo configure:1248: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
rm -rf conftest*
eval "ac_cv_func_$ac_func=yes"
else
@@ -1205,7 +1276,7 @@ else
ac_cv_c_stack_direction=0
else
cat > conftest.$ac_ext <<EOF
-#line 1209 "configure"
+#line 1280 "configure"
#include "confdefs.h"
find_stack_direction ()
{
@@ -1224,7 +1295,7 @@ main ()
exit (find_stack_direction() < 0);
}
EOF
-eval $ac_link
+{ (eval echo configure:1299: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
if test -s conftest && (./conftest; exit) 2>/dev/null; then
ac_cv_c_stack_direction=1
else
@@ -1248,15 +1319,17 @@ if eval "test \"`echo '$''{'ac_cv_func_$
echo $ac_n "(cached) $ac_c" 1>&6
else
cat > conftest.$ac_ext <<EOF
-#line 1252 "configure"
+#line 1323 "configure"
#include "confdefs.h"
/* System header to define __stub macros and hopefully few prototypes,
which can conflict with char $ac_func(); below. */
#include <assert.h>
/* Override any gcc2 internal prototype to avoid an error. */
+/* We use char because int might match the return type of a gcc2
+ builtin and then its argument prototype would still apply. */
char $ac_func();
-int main() { return 0; }
+int main() { t(); return 0; }
int t() {
/* The GNU C library defines this for functions which it implements
@@ -1270,7 +1343,7 @@ $ac_func();
; return 0; }
EOF
-if eval $ac_link; then
+if { (eval echo configure:1347: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
rm -rf conftest*
eval "ac_cv_func_$ac_func=yes"
else
@@ -1346,7 +1419,7 @@ trap 'rm -f $CONFIG_STATUS conftest*; ex
# Protect against shell expansion while executing Makefile rules.
# Protect against Makefile macro expansion.
cat > conftest.defs <<\EOF
-s%#define \([A-Za-z_][A-Za-z0-9_]*\) \(.*\)%-D\1=\2%g
+s%#define \([A-Za-z_][A-Za-z0-9_]*\) *\(.*\)%-D\1=\2%g
s%[ `~#$^&*(){}\\|;'"<>?]%\\&%g
s%\[%\\&%g
s%\]%\\&%g
@@ -1360,7 +1433,9 @@ rm -f conftest.defs
: ${CONFIG_STATUS=./config.status}
echo creating $CONFIG_STATUS
-rm -f $CONFIG_STATUS
+# Some systems, like AmigaOS, won't allow you to remove a script that is
+# being executed, so just move it out of the way instead.
+if test -f $CONFIG_STATUS; then mv $CONFIG_STATUS $CONFIG_STATUS.old; else true; fi
cat > $CONFIG_STATUS <<EOF
#! /bin/sh
# Generated automatically by configure.
@@ -1381,7 +1456,7 @@ do
echo "running \${CONFIG_SHELL-/bin/sh} $0 $ac_configure_args --no-create --no-recursion"
exec \${CONFIG_SHELL-/bin/sh} $0 $ac_configure_args --no-create --no-recursion ;;
-version | --version | --versio | --versi | --vers | --ver | --ve | --v)
- echo "$CONFIG_STATUS generated by autoconf version 2.7"
+ echo "$CONFIG_STATUS generated by autoconf version 2.10"
exit 0 ;;
-help | --help | --hel | --he | --h)
echo "\$ac_cs_usage"; exit 0 ;;
@@ -1421,6 +1496,9 @@ s%@libdir@%$libdir%g
s%@includedir@%$includedir%g
s%@oldincludedir@%$oldincludedir%g
s%@infodir@%$infodir%g
+s%@guidedir@%$guidedir%g
+s%@psdir@%$psdir%g
+s%@dvidir@%$dvidir%g
s%@mandir@%$mandir%g
s%@CC@%$CC%g
s%@INSTALL_PROGRAM@%$INSTALL_PROGRAM%g
@@ -1493,6 +1571,7 @@ rm -f conftest.subs
exit 0
EOF
chmod +x $CONFIG_STATUS
+rm -f CONFIG.STATUS.old
rm -fr confdefs* $ac_clean_files
test "$no_create" = yes || ${CONFIG_SHELL-/bin/sh} $CONFIG_STATUS || exit 1
diff -rup --new-file baseline/fsf/bison/main.c amiga/fsf/bison/main.c
--- baseline/fsf/bison/main.c Sun Oct 15 09:44:08 1995
+++ amiga/fsf/bison/main.c Sat Sep 28 00:00:00 1996
@@ -163,7 +163,13 @@ warn(s)
fprintf(stderr, "(\"%s\", line %d) error: %s\n",
infile, lineno, s);
+#ifndef __amigaos__
+ /* The ADE contains at least one program (f2c) where warnings are
+ generated by the grammar files, so don't abort for now. I'm not
+ even sure why a warnings were changed to be errors, other than
+ to try and force people to fix their grammar files. -fnf */
failure = 1;
+#endif
}
/* Print a warning message containing the string for the integer X1.
diff -rup --new-file baseline/fsf/bison/manifests/bin amiga/fsf/bison/manifests/bin
--- baseline/fsf/bison/manifests/bin Wed Dec 31 17:00:00 1969
+++ amiga/fsf/bison/manifests/bin Sat Sep 28 00:00:00 1996
@@ -0,0 +1,15 @@
+COPYING
+COPYING.info
+bin/bison
+dvi/bison.dvi
+guide/bison.guide
+info/bison.info
+info/bison.info-1
+info/bison.info-2
+info/bison.info-3
+info/bison.info-4
+info/bison.info-5
+man/man1/bison.1
+ps/bison.ps
+share/bison.hairy
+share/bison.simple
diff -rup --new-file baseline/fsf/bison/manifests/src amiga/fsf/bison/manifests/src
--- baseline/fsf/bison/manifests/src Wed Dec 31 17:00:00 1969
+++ amiga/fsf/bison/manifests/src Sat Sep 28 00:00:00 1996
@@ -0,0 +1,58 @@
+fsf/bison/BeOS.diffs
+fsf/bison/COPYING
+fsf/bison/ChangeLog
+fsf/bison/INSTALL
+fsf/bison/LR0.c
+fsf/bison/Makefile.in
+fsf/bison/NEWS
+fsf/bison/Product-Info
+fsf/bison/README
+fsf/bison/REFERENCES
+fsf/bison/alloca.c
+fsf/bison/allocate.c
+fsf/bison/bison.1
+fsf/bison/bison.cld
+fsf/bison/bison.hairy
+fsf/bison/bison.rnh
+fsf/bison/bison.simple
+fsf/bison/bison.texinfo
+fsf/bison/build.com
+fsf/bison/closure.c
+fsf/bison/configure
+fsf/bison/configure.bat
+fsf/bison/configure.in
+fsf/bison/conflicts.c
+fsf/bison/derives.c
+fsf/bison/files.c
+fsf/bison/files.h
+fsf/bison/getargs.c
+fsf/bison/getopt.c
+fsf/bison/getopt.h
+fsf/bison/getopt1.c
+fsf/bison/gram.c
+fsf/bison/gram.h
+fsf/bison/install-sh
+fsf/bison/lalr.c
+fsf/bison/lex.c
+fsf/bison/lex.h
+fsf/bison/machine.h
+fsf/bison/main.c
+fsf/bison/manifests/bin
+fsf/bison/manifests/src
+fsf/bison/mkinstalldirs
+fsf/bison/new.h
+fsf/bison/nullable.c
+fsf/bison/output.c
+fsf/bison/print.c
+fsf/bison/reader.c
+fsf/bison/reduce.c
+fsf/bison/state.h
+fsf/bison/symtab.c
+fsf/bison/symtab.h
+fsf/bison/system.h
+fsf/bison/texinfo.tex
+fsf/bison/types.h
+fsf/bison/version.c
+fsf/bison/vmsgetargs.c
+fsf/bison/vmshlp.mar
+fsf/bison/warshall.c
diff -rup --new-file baseline/fsf/bison/output.c amiga/fsf/bison/output.c
--- baseline/fsf/bison/output.c Wed Jan 24 20:56:24 1996
+++ amiga/fsf/bison/output.c Sat Sep 28 00:00:00 1996
@@ -266,7 +266,8 @@ output()
fprintf(ftable, "#include <stdio.h>\n\n");
/* Make "const" do nothing if not in ANSI C. */
- fprintf (ftable, "#ifndef __cplusplus\n#ifndef __STDC__\n#define const\n#endif\n#endif\n\n");
+ /* However don't override a previous #define if one exists. -fnf */
+ fprintf (ftable, "#ifndef __cplusplus\n#ifndef __STDC__\n#ifndef const\n#define const\n#endif\n#endif\n#endif\n\n");
free_itemsets();
output_defines();