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1.1 root 1: /* Copyright (c) 1979 Regents of the University of California */
2:
3: static char sccsid[] = "@(#)yyparse.c 1.1 8/27/80";
4:
5: #include "whoami.h"
6: #include "0.h"
7: #include "yy.h"
8:
9: /*
10: * Parser for 'yacc' output.
11: * Specifially Modified for Berkeley Pascal
12: */
13:
14: int yystate; /* Current parser state */
15: int *yypv;
16: unsigned yytshifts 1; /* Number of "true" shifts */
17:
18: /*
19: * Parse Tables
20: */
21: int yygo[];
22: int yypgo[];
23: int yyr1[];
24: int yyr2[];
25: int yyact[];
26: int yypact[];
27:
28: /*
29: * Parse and parallel semantic stack
30: */
31: int yyv[MAXDEPTH];
32: int yys[MAXDEPTH];
33:
34: /*
35: * This routine parses the input stream, and
36: * returns if it accepts, or if an unrecoverable syntax
37: * error is encountered.
38: */
39: yyparse()
40: {
41: register int *ps, n, *p;
42: int paniced, *panicps, idfail;
43:
44: yystate = 0;
45: yychar = yylex();
46: OY.Yychar = -1;
47: yyshifts = 3;
48: paniced = 0;
49: ps = &yys[0]-1;
50: yypv = &yyv[0]-1;
51: #ifdef PXP
52: yypw = &yyw[0]-1;
53: #endif
54:
55: stack:
56: /*
57: * Push new state and value.
58: */
59: if (yypv >= &yyv[MAXDEPTH-1]) {
60: yerror("Parse stack overflow");
61: pexit(DIED);
62: }
63: *++ps = yystate;
64: *++yypv = yyval;
65: #ifdef PXP
66: yypw++;
67: #endif
68: newstate:
69: /*
70: * Locate parsing actions for the
71: * new parser state.
72: */
73: p = &yyact[ yypact[yystate+1] ];
74: actn:
75: /*
76: * Search the parse actions table
77: * for something useful to do.
78: * While n is non-positive, it is the negation
79: * of the token we are testing for.
80: */
81: #ifdef PI
82: if ((n = *p++) <= 0) {
83: if (yychar < 0)
84: yychar = yylex();
85: do
86: if ((n =+ yychar) != 0)
87: p++;
88: while ((n = *p++) <= 0);
89: }
90: #else
91: while ((n = *p++) <= 0)
92: if ((n =+ yychar) != 0)
93: p++;
94: #endif
95: switch (n >> 12) {
96:
97: /*
98: * Shift.
99: */
100: case 2:
101: #ifdef PXP
102: yypw[1].Wseqid = yyseqid;
103: yypw[1].Wcol = yycol;
104: #endif
105: OYcopy();
106: yystate = n & 07777;
107: yyval = yylval;
108: #ifdef PI
109: yychar = -1;
110: #else
111: yychar = yylex();
112: #endif
113: yyshifts++;
114: yytshifts++;
115: goto stack;
116:
117: /*
118: * Reduce.
119: */
120: case 3:
121: n =& 07777;
122: N = yyr2[n];
123: if (N == 1 && OY.Yychar == YID && !yyEactr(n, yypv[0])) {
124: idfail = 1;
125: goto errin;
126: }
127: OY.Yychar = -1;
128: ps =- N;
129: yypv =- N;
130: #ifdef PXP
131: yypw =- N;
132: #endif
133: yyval = yypv[1];
134: yyactr(n);
135: /*
136: * Use goto table to find next state.
137: */
138: p = &yygo[yypgo[yyr1[n]]];
139: while (*p != *ps && *p >= 0)
140: p =+ 2;
141: yystate = p[1];
142: goto stack;
143:
144: /*
145: * Accept.
146: */
147: case 4:
148: return;
149:
150: /*
151: * Error.
152: */
153: case 1:
154: idfail = 0;
155: errin:
156: if ((paniced || yyshifts != 0) && yyrecover(ps, idfail)) {
157: paniced = 0;
158: ps = Ps;
159: yystate = *ps;
160: goto newstate;
161: }
162: /*
163: * Find a state where 'error' is a
164: * legal shift action.
165: */
166: if (paniced && yyshifts <= 0 && ps >= panicps) {
167: yypv =- (ps - panicps) + 1;
168: #ifdef PXP
169: yypw =- (ps - panicps) + 1;
170: #endif
171: ps = panicps - 1;
172: }
173: while (ps >= yys) {
174: for (p = &yyact[ yypact[*ps+1] ] ; *p <= 0; p=+ 2)
175: if (*p == -256) {
176: panicps = ps;
177: yystate= p[1] & 07777;
178: yyOshifts = yyshifts;
179: yyshifts = 0;
180: paniced = 1;
181: goto stack;
182: }
183: --ps;
184: --yypv;
185: #ifdef PXP
186: --yypw;
187: #endif
188: #ifdef PI
189: if (OY.Yychar != YID)
190: syneflg++;
191: #endif
192: OY.Yychar = -1;
193: }
194: if (yychar == YEOF)
195: yyunexeof();
196: if (yystate == 1)
197: yyexeof();
198: yerror("Unrecoverable syntax error - QUIT");
199: return;
200: }
201: panic("yyparse");
202: }
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