1 /*- 2 * Copyright (c) 1980, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 static char sccsid[] = "@(#)yyparse.c 8.1 (Berkeley) 06/06/93"; 10 #endif /* not lint */ 11 12 #include "whoami.h" 13 #include "0.h" 14 #include "tree_ty.h" /* must be included for yy.h */ 15 #include "yy.h" 16 17 /* 18 * Parser for 'yacc' output. 19 * Specifially Modified for Berkeley Pascal 20 */ 21 22 int yystate; /* Current parser state */ 23 union semstack *yypv; 24 unsigned yytshifts = 1; /* Number of "true" shifts */ 25 26 /* 27 * Parse Tables 28 */ 29 int yygo[]; 30 int yypgo[]; 31 int yyr1[]; 32 int yyr2[]; 33 int yyact[]; 34 int yypact[]; 35 36 /* 37 * Parse and parallel semantic stack 38 */ 39 union semstack yyv[MAXDEPTH]; 40 int yys[MAXDEPTH]; 41 42 /* 43 * This routine parses the input stream, and 44 * returns if it accepts, or if an unrecoverable syntax 45 * error is encountered. 46 */ 47 yyparse() 48 { 49 register int *ps, n, *p; 50 int paniced, *panicps, idfail; 51 52 #ifdef lint 53 panicps = (int *) 0; 54 #endif 55 yystate = 0; 56 yychar = yylex(); 57 OY.Yychar = -1; 58 yyshifts = 3; 59 paniced = 0; 60 ps = &yys[0]-1; 61 yypv = &yyv[0]-1; 62 #ifdef PXP 63 yypw = &yyw[0]-1; 64 #endif 65 66 stack: 67 /* 68 * Push new state and value. 69 */ 70 if (yypv >= &yyv[MAXDEPTH-1]) { 71 yerror("Parse stack overflow"); 72 pexit(DIED); 73 } 74 *++ps = yystate; 75 *++yypv = yyval; 76 #ifdef PXP 77 yypw++; 78 #endif 79 newstate: 80 /* 81 * Locate parsing actions for the 82 * new parser state. 83 */ 84 p = &yyact[ yypact[yystate+1] ]; 85 /* 86 * Search the parse actions table 87 * for something useful to do. 88 * While n is non-positive, it is the negation 89 * of the token we are testing for. 90 */ 91 #ifdef PI 92 if ((n = *p++) <= 0) { 93 if (yychar < 0) 94 yychar = yylex(); 95 do 96 if ((n += yychar) != 0) 97 p++; 98 while ((n = *p++) <= 0); 99 } 100 #else 101 while ((n = *p++) <= 0) 102 if ((n += yychar) != 0) 103 p++; 104 #endif 105 switch (n >> 12) { 106 107 /* 108 * Shift. 109 */ 110 case 2: 111 #ifdef PXP 112 yypw[1].Wseqid = yyseqid; 113 yypw[1].Wcol = yycol; 114 #endif 115 OYcopy(); 116 yystate = n & 07777; 117 yyval.i_entry = yylval; 118 #ifdef PI 119 yychar = -1; 120 #else 121 yychar = yylex(); 122 #endif 123 yyshifts++; 124 yytshifts++; 125 goto stack; 126 127 /* 128 * Reduce. 129 */ 130 case 3: 131 n &= 07777; 132 N = yyr2[n]; 133 if (N == 1 && OY.Yychar == YID && !yyEactr(n, 134 yypv[0].cptr)) { 135 idfail = 1; 136 goto errin; 137 } 138 OY.Yychar = -1; 139 ps -= N; 140 yypv -= N; 141 #ifdef PXP 142 yypw -= N; 143 #endif 144 yyval = yypv[1]; 145 yyactr(n); 146 /* 147 * Use goto table to find next state. 148 */ 149 p = &yygo[yypgo[yyr1[n]]]; 150 while (*p != *ps && *p >= 0) 151 p += 2; 152 yystate = p[1]; 153 goto stack; 154 155 /* 156 * Accept. 157 */ 158 case 4: 159 return; 160 161 /* 162 * Error. 163 */ 164 case 1: 165 idfail = 0; 166 errin: 167 if ((paniced || yyshifts != 0) && yyrecover(ps, idfail)) { 168 paniced = 0; 169 ps = Ps; 170 yystate = *ps; 171 goto newstate; 172 } 173 /* 174 * Find a state where 'error' is a 175 * legal shift action. 176 */ 177 if (paniced && yyshifts <= 0 && ps >= panicps) { 178 yypv -= (ps - panicps) + 1; 179 #ifdef PXP 180 yypw -= (ps - panicps) + 1; 181 #endif 182 ps = panicps - 1; 183 } 184 while (ps >= yys) { 185 for (p = &yyact[ yypact[*ps+1] ] ; *p <= 0; p += 2) 186 if (*p == -256) { 187 panicps = ps; 188 yystate= p[1] & 07777; 189 yyOshifts = yyshifts; 190 yyshifts = 0; 191 paniced = 1; 192 goto stack; 193 } 194 --ps; 195 --yypv; 196 #ifdef PXP 197 --yypw; 198 #endif 199 #ifdef PI 200 if (OY.Yychar != YID) 201 syneflg = TRUE; 202 #endif 203 OY.Yychar = -1; 204 } 205 if (yychar == YEOF) 206 yyunexeof(); 207 if (yystate == 1) 208 yyexeof(); 209 yerror("Unrecoverable syntax error - QUIT"); 210 return; 211 } 212 panic("yyparse"); 213 } 214