1 /* Copyright (c) 1979 Regents of the University of California */ 2 3 static char sccsid[] = "@(#)yyparse.c 1.2 03/08/81"; 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 = TRUE; 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 } 203