![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to yyparse.c CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [CSRG BSD Unix] / 43BSDReno / pgrm / pascal / src|
Return to yyparse.c CVS log | Up to [CSRG BSD Unix] / 43BSDReno / pgrm / pascal / src |
1.1 root 1: /*
2: * Copyright (c) 1980 Regents of the University of California.
3: * All rights reserved. The Berkeley software License Agreement
4: * specifies the terms and conditions for redistribution.
5: */
6:
7: #ifndef lint
8: static char sccsid[] = "@(#)yyparse.c 5.1 (Berkeley) 6/5/85";
9: #endif not lint
10:
11: #include "whoami.h"
12: #include "0.h"
13: #include "tree_ty.h" /* must be included for yy.h */
14: #include "yy.h"
15:
16: /*
17: * Parser for 'yacc' output.
18: * Specifially Modified for Berkeley Pascal
19: */
20:
21: int yystate; /* Current parser state */
22: union semstack *yypv;
23: unsigned yytshifts = 1; /* Number of "true" shifts */
24:
25: /*
26: * Parse Tables
27: */
28: int yygo[];
29: int yypgo[];
30: int yyr1[];
31: int yyr2[];
32: int yyact[];
33: int yypact[];
34:
35: /*
36: * Parse and parallel semantic stack
37: */
38: union semstack yyv[MAXDEPTH];
39: int yys[MAXDEPTH];
40:
41: /*
42: * This routine parses the input stream, and
43: * returns if it accepts, or if an unrecoverable syntax
44: * error is encountered.
45: */
46: yyparse()
47: {
48: register int *ps, n, *p;
49: int paniced, *panicps, idfail;
50:
51: #ifdef lint
52: panicps = (int *) 0;
53: #endif
54: yystate = 0;
55: yychar = yylex();
56: OY.Yychar = -1;
57: yyshifts = 3;
58: paniced = 0;
59: ps = &yys[0]-1;
60: yypv = &yyv[0]-1;
61: #ifdef PXP
62: yypw = &yyw[0]-1;
63: #endif
64:
65: stack:
66: /*
67: * Push new state and value.
68: */
69: if (yypv >= &yyv[MAXDEPTH-1]) {
70: yerror("Parse stack overflow");
71: pexit(DIED);
72: }
73: *++ps = yystate;
74: *++yypv = yyval;
75: #ifdef PXP
76: yypw++;
77: #endif
78: newstate:
79: /*
80: * Locate parsing actions for the
81: * new parser state.
82: */
83: p = &yyact[ yypact[yystate+1] ];
84: /*
85: * Search the parse actions table
86: * for something useful to do.
87: * While n is non-positive, it is the negation
88: * of the token we are testing for.
89: */
90: #ifdef PI
91: if ((n = *p++) <= 0) {
92: if (yychar < 0)
93: yychar = yylex();
94: do
95: if ((n += yychar) != 0)
96: p++;
97: while ((n = *p++) <= 0);
98: }
99: #else
100: while ((n = *p++) <= 0)
101: if ((n += yychar) != 0)
102: p++;
103: #endif
104: switch (n >> 12) {
105:
106: /*
107: * Shift.
108: */
109: case 2:
110: #ifdef PXP
111: yypw[1].Wseqid = yyseqid;
112: yypw[1].Wcol = yycol;
113: #endif
114: OYcopy();
115: yystate = n & 07777;
116: yyval.i_entry = yylval;
117: #ifdef PI
118: yychar = -1;
119: #else
120: yychar = yylex();
121: #endif
122: yyshifts++;
123: yytshifts++;
124: goto stack;
125:
126: /*
127: * Reduce.
128: */
129: case 3:
130: n &= 07777;
131: N = yyr2[n];
132: if (N == 1 && OY.Yychar == YID && !yyEactr(n,
133: yypv[0].cptr)) {
134: idfail = 1;
135: goto errin;
136: }
137: OY.Yychar = -1;
138: ps -= N;
139: yypv -= N;
140: #ifdef PXP
141: yypw -= N;
142: #endif
143: yyval = yypv[1];
144: yyactr(n);
145: /*
146: * Use goto table to find next state.
147: */
148: p = &yygo[yypgo[yyr1[n]]];
149: while (*p != *ps && *p >= 0)
150: p += 2;
151: yystate = p[1];
152: goto stack;
153:
154: /*
155: * Accept.
156: */
157: case 4:
158: return;
159:
160: /*
161: * Error.
162: */
163: case 1:
164: idfail = 0;
165: errin:
166: if ((paniced || yyshifts != 0) && yyrecover(ps, idfail)) {
167: paniced = 0;
168: ps = Ps;
169: yystate = *ps;
170: goto newstate;
171: }
172: /*
173: * Find a state where 'error' is a
174: * legal shift action.
175: */
176: if (paniced && yyshifts <= 0 && ps >= panicps) {
177: yypv -= (ps - panicps) + 1;
178: #ifdef PXP
179: yypw -= (ps - panicps) + 1;
180: #endif
181: ps = panicps - 1;
182: }
183: while (ps >= yys) {
184: for (p = &yyact[ yypact[*ps+1] ] ; *p <= 0; p += 2)
185: if (*p == -256) {
186: panicps = ps;
187: yystate= p[1] & 07777;
188: yyOshifts = yyshifts;
189: yyshifts = 0;
190: paniced = 1;
191: goto stack;
192: }
193: --ps;
194: --yypv;
195: #ifdef PXP
196: --yypw;
197: #endif
198: #ifdef PI
199: if (OY.Yychar != YID)
200: syneflg = TRUE;
201: #endif
202: OY.Yychar = -1;
203: }
204: if (yychar == YEOF)
205: yyunexeof();
206: if (yystate == 1)
207: yyexeof();
208: yerror("Unrecoverable syntax error - QUIT");
209: return;
210: }
211: panic("yyparse");
212: }
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.