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TeX 1995 July
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TeX CD-ROM July 1995 (Disc 1)(Walnut Creek)(1995).ISO
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macros
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latex209
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contrib
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rail
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gram.y
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1993-01-11
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/* gram.y - yacc grammar for rail program */
%{
#include <stdio.h>
#include "rail.h"
char optchar;
%}
/* identifier */
%token <id> IDENTIFIER
/* number */
%token <num> NUMBER
/* [annotation] */
%token <text> ANNOT
/* \rail@i \rail@p \rail@t \\ */
%token RAILI RAILP RAILT RAILCR
/* TeX control sequence */
%token CS
/* 'c' "string" */
%token <text> STRING
%type <rule> rule rules
%type <body> body body0 body1 body2e body2 body3 body4e body4 empty
%type <text> annot
%start rails
%%
rails : rails rail
| rail
;
rail : RAILI raili
| RAILP railp
| RAILT railt
| error
;
railp :
'{'
{
fprintf(outf,"\\rail@p {");
copy=1;
optchar = '-'; }
options '}'
{
fprintf(outf,"\n");
copy=0;
}
;
options : /*empty*/
| options '-'
{ optchar = '-'; }
| options '+'
{ optchar = '+'; }
| options IDENTIFIER
{
if(setopt(optchar,$2->name)==0)
error("unknown option",(char *)NULL);
if($2->kind==UNKNOWN)
delete($2);
}
;
railt : '{' IDENTIFIER '}'
{
if($2->kind==UNKNOWN || $2->kind==TOKEN)
$2->kind=TERM;
else
redef($2);
fprintf(outf,"\\rail@t {%s}\n",$2->name);
}
;
raili : '{' NUMBER '}'
{
fprintf(outf,"\\rail@i {%d}",$2);
copy=1;
}
'{' rules '}'
{ copy=0;
fprintf(outf,"\n");
fprintf(outf,"\\rail@o {%d}{\n",$2);
outrule($6); /* embedded action is $4 */
freerule($6);
fprintf(outf,"}\n");
}
;
rules : rules ';' rule
{ $$=addrule($1,$3); }
| rules ';'
{ $$=$1; }
| rule
| error
{ $$=NULL; }
;
rule : IDENTIFIER ':'
{ errorid=$1; }
body
{
if($1->kind==UNKNOWN || $1->kind==TOKEN)
$1->kind=NTERM;
else
redef($1);
$$=newrule($1,$4); /* embedded action is $3 */
errorid=NULL;
}
| body
{
anonymous++;
$$=newrule((IDTYPE *)NULL,$1);
}
;
body : body0
{ $$=$1; $$->done=1; }
;
body0 : body0 '|' ANNOT body1
{
$$=newbody(ANNOTE,NULLBODY,NULLBODY);
$$->text=$3;
$$=addbody(CAT,$$,$4);
$$=addbody(BAR,$1,$$);
}
| body0 '|' body1
{ $$=addbody(BAR,$1,$3); }
| ANNOT body1
{
$$=newbody(ANNOTE,NULLBODY,NULLBODY);
$$->text=$1;
$$=addbody(CAT,$$,$2);
}
| body1
;
body1 : body2 '*' body4e
{
if(altstar && isemptybody($3)) {
$$=newbody(EMPTY,NULLBODY,NULLBODY);
$$=addbody(PLUS,$$,revbody($1));
} else {
$$=newbody(EMPTY,NULLBODY,NULLBODY);
$$=addbody(BAR,$$,addbody(PLUS,$1,revbody($3)));
}
}
| body2 '+' body4e
{ $$=newbody(PLUS,$1,revbody($3)); }
| body2e
;
body2e : body2 | empty ;
body2 : body2 body3
{ $$=addbody(CAT,$1,$2); }
| body3
;
body3 : body4 '?'
{ $$=addbody(BAR,newbody(EMPTY,NULLBODY,NULLBODY),$1); }
| body4
;
body4e : body4 | empty ;
body4 : '(' body0 ')'
{ $$=$2; $$->done=1; }
| STRING annot
{
$$=newbody(STRNG,NULLBODY,NULLBODY);
$$->annot=$2;
$$->text=$1;
}
| IDENTIFIER annot
{
if($1->kind==UNKNOWN)
$1->kind=TOKEN;
$$=newbody(IDENT,NULLBODY,NULLBODY);
$$->annot=$2;
$$->id=$1;
}
| RAILCR
{ $$=newbody(CR,NULLBODY,NULLBODY); }
;
empty : /*empty*/
{ $$=newbody(EMPTY,NULLBODY,NULLBODY); }
;
annot : ANNOT
{ $$=$1; }
| /*empty*/
{ $$=NULL; }
;
%%