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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[] = "@(#)yypanic.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: struct yytok oldpos;
17: /*
18: * The routine yyPerror coordinates the panic when
19: * the correction routines fail. Three types of panics
20: * are possible - those in a declaration part, those
21: * in a statement part, and those in an expression.
22: *
23: * Declaration part panics consider insertion of "begin",
24: * expression part panics will stop on more symbols.
25: * The panics are otherwise the same.
26: *
27: * ERROR MESSAGE SUPPRESSION STRATEGY: August 11, 1977
28: *
29: * If the parser has not made at least 2 moves since the last point of
30: * error then we want to suppress the supplied error message.
31: * Otherwise we print it.
32: * We then skip input up to the next solid symbol.
33: */
34: yyPerror(cp, kind)
35: char *cp;
36: register int kind;
37: {
38: register int ishifts, brlev;
39:
40: copy((char *) (&oldpos), (char *) (&Y), sizeof oldpos);
41: brlev = 0;
42: if (yychar < 0)
43: yychar = yylex();
44: for (ishifts = yyshifts; ; yychar = yylex(), yyshifts++)
45: switch (yychar) {
46: case YILLCH:
47: yerror("Illegal character");
48: if (ishifts == yyshifts)
49: yyOshifts = 0;
50: continue;
51: case YEOF:
52: if (kind == PDECL) {
53: /*
54: * we have paniced to end of file
55: * during declarations. Separately
56: * compiled segments can syntactically
57: * exit without any error message, so
58: * we force one here.
59: */
60: yerror(cp);
61: continuation();
62: yyunexeof();
63: }
64: goto quiet;
65: case ';':
66: if (kind == PPROG)
67: continue;
68: if (kind == PDECL)
69: yychar = yylex();
70: goto resume;
71: case YEND:
72: if (kind == PPROG)
73: continue;
74: case YPROCEDURE:
75: case YFUNCTION:
76: goto resume;
77: case YLABEL:
78: case YTYPE:
79: case YCONST:
80: case YVAR:
81: if (kind == PSTAT) {
82: yerror("Declaration found when statement expected");
83: goto quiet;
84: }
85: case YBEGIN:
86: goto resume;
87: case YFOR:
88: case YREPEAT:
89: case YWHILE:
90: case YGOTO:
91: case YIF:
92: if (kind != PDECL)
93: goto resume;
94: yerror("Expected keyword begin after declarations, before statements");
95: unyylex(&Y);
96: yychar = YBEGIN;
97: yylval = nullsem(YBEGIN);
98: goto quiet;
99: case YTHEN:
100: case YELSE:
101: case YDO:
102: if (kind == PSTAT) {
103: yychar = yylex();
104: goto resume;
105: }
106: if (kind == PEXPR)
107: goto resume;
108: continue;
109: case ')':
110: case ']':
111: if (kind != PEXPR)
112: continue;
113: if (brlev == 0)
114: goto resume;
115: if (brlev > 0)
116: brlev--;
117: continue;
118: case '(':
119: case '[':
120: brlev++;
121: continue;
122: case ',':
123: if (brlev != 0)
124: continue;
125: case YOF:
126: case YTO:
127: case YDOWNTO:
128: if (kind == PEXPR)
129: goto resume;
130: continue;
131: #ifdef PI
132: /*
133: * A rough approximation for now
134: * Should be much more lenient on suppressing
135: * warnings.
136: */
137: case YID:
138: syneflg = TRUE;
139: continue;
140: #endif
141: }
142: resume:
143: if (yyOshifts >= 2) {
144: if (yychar != -1)
145: unyylex(&Y);
146: copy((char *) (&Y), (char *) (&oldpos), sizeof Y);
147: yerror(cp);
148: yychar = yylex();
149: }
150: quiet:
151: if (yyshifts - ishifts > 2 && opt('r')) {
152: setpfx('r');
153: yerror("Parsing resumes");
154: }
155: /*
156: * If we paniced in the statement part,
157: * and didn't stop at a ';', then we insert
158: * a ';' to prevent the recovery from immediately
159: * inserting one and complaining about it.
160: */
161: if (kind == PSTAT && yychar != ';') {
162: unyylex(&Y);
163: yyshifts--;
164: yytshifts--;
165: yychar = ';';
166: yylval = nullsem(';');
167: }
168: }
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