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yyparse.c
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C/C++ Source or Header
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1980-02-17
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3KB
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213 lines
/* Copyright (c) 1979 Regents of the University of California */
#
/*
* pi - Pascal interpreter code translator
*
* Charles Haley, Bill Joy UCB
* Version 1.2 January 1979
*
*
* pxp - Pascal execution profiler
*
* Bill Joy UCB
* Version 1.2 January 1979
*/
#include "0.h"
#include "yy.h"
/*
* Parser for 'yacc' output.
* Specifially Modified for Berkeley Pascal
*/
int yystate; /* Current parser state */
int *yypv;
unsigned yytshifts 1; /* Number of "true" shifts */
/*
* Parse Tables
*/
int yygo[];
int yypgo[];
int yyr1[];
int yyr2[];
int yyact[];
int yypact[];
/*
* Parse and parallel semantic stack
*/
int yyv[MAXDEPTH];
int yys[MAXDEPTH];
/*
* This routine parses the input stream, and
* returns if it accepts, or if an unrecoverable syntax
* error is encountered.
*/
yyparse()
{
register int *ps, n, *p;
int paniced, *panicps, idfail;
yystate = 0;
yychar = yylex();
OY.Yychar = -1;
yyshifts = 3;
paniced = 0;
ps = &yys[0]-1;
yypv = &yyv[0]-1;
#ifdef PXP
yypw = &yyw[0]-1;
#endif
stack:
/*
* Push new state and value.
*/
if (yypv >= &yyv[MAXDEPTH-1]) {
yerror("Parse stack overflow");
pexit(DIED);
}
*++ps = yystate;
*++yypv = yyval;
#ifdef PXP
yypw++;
#endif
newstate:
/*
* Locate parsing actions for the
* new parser state.
*/
p = &yyact[ yypact[yystate+1] ];
actn:
/*
* Search the parse actions table
* for something useful to do.
* While n is non-positive, it is the negation
* of the token we are testing for.
*/
#ifdef PI
if ((n = *p++) <= 0) {
if (yychar < 0)
yychar = yylex();
do
if ((n =+ yychar) != 0)
p++;
while ((n = *p++) <= 0);
}
#else
while ((n = *p++) <= 0)
if ((n =+ yychar) != 0)
p++;
#endif
switch (n >> 12) {
/*
* Shift.
*/
case 2:
#ifdef PXP
yypw[1].Wseqid = yyseqid;
yypw[1].Wcol = yycol;
#endif
OYcopy();
yystate = n & 07777;
yyval = yylval;
#ifdef PI
yychar = -1;
#else
yychar = yylex();
#endif
yyshifts++;
yytshifts++;
goto stack;
/*
* Reduce.
*/
case 3:
n =& 07777;
N = yyr2[n];
if (N == 1 && OY.Yychar == YID && !yyEactr(n, yypv[0])) {
idfail = 1;
goto errin;
}
OY.Yychar = -1;
ps =- N;
yypv =- N;
#ifdef PXP
yypw =- N;
#endif
yyval = yypv[1];
yyactr(n);
/*
* Use goto table to find next state.
*/
p = &yygo[yypgo[yyr1[n]]];
while (*p != *ps && *p >= 0)
p =+ 2;
yystate = p[1];
goto stack;
/*
* Accept.
*/
case 4:
return;
/*
* Error.
*/
case 1:
idfail = 0;
errin:
if ((paniced || yyshifts != 0) && yyrecover(ps, idfail)) {
paniced = 0;
ps = Ps;
yystate = *ps;
goto newstate;
}
/*
* Find a state where 'error' is a
* legal shift action.
*/
if (paniced && yyshifts <= 0 && ps >= panicps) {
yypv =- (ps - panicps) + 1;
#ifdef PXP
yypw =- (ps - panicps) + 1;
#endif
ps = panicps - 1;
}
while (ps >= yys) {
for (p = &yyact[ yypact[*ps+1] ] ; *p <= 0; p=+ 2)
if (*p == -256) {
panicps = ps;
yystate= p[1] & 07777;
yyOshifts = yyshifts;
yyshifts = 0;
paniced = 1;
goto stack;
}
--ps;
--yypv;
#ifdef PXP
--yypw;
#endif
#ifdef PI
if (OY.Yychar != YID)
syneflg++;
#endif
OY.Yychar = -1;
}
if (yychar == YEOF)
yyunexeof();
if (yystate == 1)
yyexeof();
yerror("Unrecoverable syntax error - QUIT");
return;
}
panic("yyparse");
}