projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| d503ec6c BJ |
1 | /* Copyright (c) 1979 Regents of the University of California */ |
| 2 | # | |
| 3 | /* | |
| 4 | * pi - Pascal interpreter code translator | |
| 5 | * | |
| 6 | * Charles Haley, Bill Joy UCB | |
| 7 | * Version 1.2 January 1979 | |
| 8 | * | |
| 9 | * | |
| 10 | * pxp - Pascal execution profiler | |
| 11 | * | |
| 12 | * Bill Joy UCB | |
| 13 | * Version 1.2 January 1979 | |
| 14 | */ | |
| 15 | ||
| 16 | #include "0.h" | |
| 17 | #include "yy.h" | |
| 18 | ||
| 19 | struct yytok oldpos; | |
| 20 | /* | |
| 21 | * The routine yyPerror coordinates the panic when | |
| 22 | * the correction routines fail. Three types of panics | |
| 23 | * are possible - those in a declaration part, those | |
| 24 | * in a statement part, and those in an expression. | |
| 25 | * | |
| 26 | * Declaration part panics consider insertion of "begin", | |
| 27 | * expression part panics will stop on more symbols. | |
| 28 | * The panics are otherwise the same. | |
| 29 | * | |
| 30 | * ERROR MESSAGE SUPPRESSION STRATEGY: August 11, 1977 | |
| 31 | * | |
| 32 | * If the parser has not made at least 2 moves since the last point of | |
| 33 | * error then we want to suppress the supplied error message. | |
| 34 | * Otherwise we print it. | |
| 35 | * We then skip input up to the next solid symbol. | |
| 36 | */ | |
| 37 | yyPerror(cp, kind) | |
| 38 | char *cp; | |
| 39 | register int kind; | |
| 40 | { | |
| 41 | register int ishifts, brlev; | |
| 42 | ||
| 43 | copy(&oldpos, &Y, sizeof oldpos); | |
| 44 | brlev = 0; | |
| 45 | if (yychar < 0) | |
| 46 | yychar = yylex(); | |
| 47 | for (ishifts = yyshifts; ; yychar = yylex(), yyshifts++) | |
| 48 | switch (yychar) { | |
| 49 | case YILLCH: | |
| 50 | yerror("Illegal character"); | |
| 51 | if (ishifts == yyshifts) | |
| 52 | yyOshifts = 0; | |
| 53 | continue; | |
| 54 | case YEOF: | |
| 55 | goto quiet; | |
| 56 | case ';': | |
| 57 | if (kind == PPROG) | |
| 58 | continue; | |
| 59 | if (kind == PDECL) | |
| 60 | yychar = yylex(); | |
| 61 | goto resume; | |
| 62 | case YEND: | |
| 63 | if (kind == PPROG) | |
| 64 | continue; | |
| 65 | case YPROCEDURE: | |
| 66 | case YFUNCTION: | |
| 67 | goto resume; | |
| 68 | case YLABEL: | |
| 69 | case YTYPE: | |
| 70 | case YCONST: | |
| 71 | case YVAR: | |
| 72 | if (kind == PSTAT) { | |
| 73 | yerror("Declaration found when statement expected"); | |
| 74 | goto quiet; | |
| 75 | } | |
| 76 | case YBEGIN: | |
| 77 | goto resume; | |
| 78 | case YFOR: | |
| 79 | case YREPEAT: | |
| 80 | case YWHILE: | |
| 81 | case YGOTO: | |
| 82 | case YIF: | |
| 83 | if (kind != PDECL) | |
| 84 | goto resume; | |
| 85 | yerror("Expected keyword begin after declarations, before statements"); | |
| 86 | unyylex(&Y); | |
| 87 | yychar = YBEGIN; | |
| 88 | yylval = nullsem(YBEGIN); | |
| 89 | goto quiet; | |
| 90 | case YTHEN: | |
| 91 | case YELSE: | |
| 92 | case YDO: | |
| 93 | if (kind == PSTAT) { | |
| 94 | yychar = yylex(); | |
| 95 | goto resume; | |
| 96 | } | |
| 97 | if (kind == PEXPR) | |
| 98 | goto resume; | |
| 99 | continue; | |
| 100 | case ')': | |
| 101 | case ']': | |
| 102 | if (kind != PEXPR) | |
| 103 | continue; | |
| 104 | if (brlev == 0) | |
| 105 | goto resume; | |
| 106 | if (brlev > 0) | |
| 107 | brlev--; | |
| 108 | continue; | |
| 109 | case '(': | |
| 110 | case '[': | |
| 111 | brlev++; | |
| 112 | continue; | |
| 113 | case ',': | |
| 114 | if (brlev != 0) | |
| 115 | continue; | |
| 116 | case YOF: | |
| 117 | case YTO: | |
| 118 | case YDOWNTO: | |
| 119 | if (kind == PEXPR) | |
| 120 | goto resume; | |
| 121 | continue; | |
| 122 | #ifdef PI | |
| 123 | /* | |
| 124 | * A rough approximation for now | |
| 125 | * Should be much more lenient on suppressing | |
| 126 | * warnings. | |
| 127 | */ | |
| 128 | case YID: | |
| 129 | syneflg++; | |
| 130 | continue; | |
| 131 | #endif | |
| 132 | } | |
| 133 | resume: | |
| 134 | if (yyOshifts >= 2) { | |
| 135 | if (yychar != -1) | |
| 136 | unyylex(&Y); | |
| 137 | copy(&Y, &oldpos, sizeof Y); | |
| 138 | yerror(cp); | |
| 139 | yychar = yylex(); | |
| 140 | } | |
| 141 | quiet: | |
| 142 | if (yyshifts - ishifts > 2 && opt('r')) { | |
| 143 | setpfx('r'); | |
| 144 | yerror("Parsing resumes"); | |
| 145 | } | |
| 146 | /* | |
| 147 | * If we paniced in the statement part, | |
| 148 | * and didn't stop at a ';', then we insert | |
| 149 | * a ';' to prevent the recovery from immediately | |
| 150 | * inserting one and complaining about it. | |
| 151 | */ | |
| 152 | if (kind == PSTAT && yychar != ';') { | |
| 153 | unyylex(&Y); | |
| 154 | yyshifts--; | |
| 155 | yytshifts--; | |
| 156 | yychar = ';'; | |
| 157 | yylval = nullsem(';'); | |
| 158 | } | |
| 159 | } |