2.11BSD#431 - /usr/src/ucb/pascal/pi/yypanic.c

   1: /*	@(#)yypanic.c	2.2	SCCS id keyword	*/
   2: /* Copyright (c) 1979 Regents of the University of California */
   3: #
   4: /*
   5:  * pi - Pascal interpreter code translator
   6:  *
   7:  * Charles Haley, Bill Joy UCB
   8:  * Version 1.1 February 1978
   9:  *
  10:  *
  11:  * pxp - Pascal execution profiler
  12:  *
  13:  * Bill Joy UCB
  14:  * Version 1.1 February 1978
  15:  */
  16: 
  17: #include "whoami"
  18: #include "0.h"
  19: #include "yy.h"
  20: 
  21: struct yytok oldpos;
  22: /*
  23:  * The routine yyPerror coordinates the panic when
  24:  * the correction routines fail. Three types of panics
  25:  * are possible - those in a declaration part, those
  26:  * in a statement part, and those in an expression.
  27:  *
  28:  * Declaration part panics consider insertion of "begin",
  29:  * expression part panics will stop on more symbols.
  30:  * The panics are otherwise the same.
  31:  *
  32:  * ERROR MESSAGE SUPPRESSION STRATEGY: August 11, 1977
  33:  *
  34:  * If the parser has not made at least 2 moves since the last point of
  35:  * error then we want to suppress the supplied error message.
  36:  * Otherwise we print it.
  37:  * We then skip input up to the next solid symbol.
  38:  */
  39: yyPerror(cp, kind)
  40:     char *cp;
  41:     register int kind;
  42: {
  43:     register int ishifts, brlev;
  44: 
  45:     copy(&oldpos, &Y, sizeof oldpos);
  46:     brlev = 0;
  47:     if (yychar < 0)
  48:         yychar = yylex();
  49:     for (ishifts = yyshifts; ; yychar = yylex(), yyshifts++)
  50:         switch (yychar) {
  51:             case YILLCH:
  52:                 yerror("Illegal character");
  53:                 if (ishifts == yyshifts)
  54:                     yyOshifts = 0;
  55:                 continue;
  56:             case YEOF:
  57:                 goto quiet;
  58:             case ';':
  59:                 if (kind == PPROG)
  60:                     continue;
  61:                 if (kind == PDECL)
  62:                     yychar = yylex();
  63:                 goto resume;
  64:             case YEND:
  65:                 if (kind == PPROG)
  66:                     continue;
  67:             case YPROCEDURE:
  68:             case YFUNCTION:
  69:                 goto resume;
  70:             case YLABEL:
  71:             case YTYPE:
  72:             case YCONST:
  73:             case YVAR:
  74:                 if (kind == PSTAT) {
  75:                     yerror("Declaration found when statement expected");
  76:                     goto quiet;
  77:                 }
  78:             case YBEGIN:
  79:                 goto resume;
  80:             case YFOR:
  81:             case YREPEAT:
  82:             case YWHILE:
  83:             case YGOTO:
  84:             case YIF:
  85:                 if (kind != PDECL)
  86:                     goto resume;
  87:                 yerror("Expected keyword begin after declarations, before statements");
  88:                 unyylex(&Y);
  89:                 yychar = YBEGIN;
  90:                 yylval = nullsem(YBEGIN);
  91:                 goto quiet;
  92:             case YTHEN:
  93:             case YELSE:
  94:             case YDO:
  95:                 if (kind == PSTAT) {
  96:                     yychar = yylex();
  97:                     goto resume;
  98:                 }
  99:                 if (kind == PEXPR)
 100:                     goto resume;
 101:                 continue;
 102:             case ')':
 103:             case ']':
 104:                 if (kind != PEXPR)
 105:                     continue;
 106:                 if (brlev == 0)
 107:                     goto resume;
 108:                 if (brlev > 0)
 109:                     brlev--;
 110:                 continue;
 111:             case '(':
 112:             case '[':
 113:                 brlev++;
 114:                 continue;
 115:             case ',':
 116:                 if (brlev != 0)
 117:                     continue;
 118:             case YOF:
 119:             case YTO:
 120:             case YDOWNTO:
 121:                 if (kind == PEXPR)
 122:                     goto resume;
 123:                 continue;
 124: #ifdef PI
 125:             /*
 126: 			 * A rough approximation for now
 127: 			 * Should be much more lenient on suppressing
 128: 			 * warnings.
 129: 			 */
 130:             case YID:
 131:                 syneflg++;
 132:                 continue;
 133: #endif
 134:         }
 135: resume:
 136:     if (yyOshifts >= 2) {
 137:         if (yychar != -1)
 138:             unyylex(&Y);
 139:         copy(&Y, &oldpos, sizeof Y);
 140:         yerror(cp);
 141:         yychar = yylex();
 142:     }
 143: quiet:
 144:     if (yyshifts - ishifts > 2 && opt('r')) {
 145:         setpfx('r');
 146:         yerror("Parsing resumes");
 147:     }
 148:     /*
 149: 	 * If we paniced in the statement part,
 150: 	 * and didn't stop at a ';', then we insert
 151: 	 * a ';' to prevent the recovery from immediately
 152: 	 * inserting one and complaining about it.
 153: 	 */
 154:     if (kind == PSTAT && yychar != ';') {
 155:         unyylex(&Y);
 156:         yyshifts--;
 157:         yytshifts--;
 158:         yychar = ';';
 159:         yylval = nullsem(';');
 160:     }
 161: }

Defined functions

Defined variables