usr.bin/yacc/closure.c

   1 /*
   2  * Copyright (c) 1989 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Robert Paul Corbett.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * $FreeBSD: src/usr.bin/yacc/closure.c,v 1.6 1999/08/28 01:07:58 peter Exp $
  37  * $DragonFly: src/usr.bin/yacc/closure.c,v 1.4 2004/04/07 20:43:24 cpressey Exp $
  38  *
  39  * @(#)closure.c        5.3 (Berkeley) 5/24/93
  40  */
  41
  42 #include <stdlib.h>
  43 #include "defs.h"
  44
  45 short *itemset;
  46 short *itemsetend;
  47 unsigned *ruleset;
  48
  49 static void set_EFF(void);
  50 #ifdef DEBUG
  51 static void print_closure(int);
  52 static void print_EFF();
  53 static void print_first_derives();
  54 #endif
  55
  56 static unsigned *first_derives;
  57 static unsigned *EFF;
  58
  59
  60 static void
  61 set_EFF(void)
  62 {
  63     unsigned *row;
  64     int symbol;
  65     short *sp;
  66     int rowsize;
  67     int i;
  68     int rule;
  69
  70     rowsize = WORDSIZE(nvars);
  71     EFF = NEW2(nvars * rowsize, unsigned);
  72
  73     row = EFF;
  74     for (i = start_symbol; i < nsyms; i++)
  75     {
  76         sp = derives[i];
  77         for (rule = *sp; rule > 0; rule = *++sp)
  78         {
  79             symbol = ritem[rrhs[rule]];
  80             if (ISVAR(symbol))
  81             {
  82                 symbol -= start_symbol;
  83                 SETBIT(row, symbol);
  84             }
  85         }
  86         row += rowsize;
  87     }
  88
  89     reflexive_transitive_closure(EFF, nvars);
  90
  91 #ifdef  DEBUG
  92     print_EFF();
  93 #endif
  94 }
  95
  96
  97 void
  98 set_first_derives(void)
  99 {
 100     unsigned *rrow;
 101     unsigned *vrow;
 102     int j;
 103     unsigned k;
 104     unsigned cword = 0;
 105     short *rp;
 106
 107     int rule;
 108     int i;
 109     int rulesetsize;
 110     int varsetsize;
 111
 112     rulesetsize = WORDSIZE(nrules);
 113     varsetsize = WORDSIZE(nvars);
 114     first_derives = NEW2(nvars * rulesetsize, unsigned) - ntokens * rulesetsize;
 115
 116     set_EFF();
 117
 118     rrow = first_derives + ntokens * rulesetsize;
 119     for (i = start_symbol; i < nsyms; i++)
 120     {
 121         vrow = EFF + ((i - ntokens) * varsetsize);
 122         k = BITS_PER_WORD;
 123         for (j = start_symbol; j < nsyms; k++, j++)
 124         {
 125             if (k >= BITS_PER_WORD)
 126             {
 127                 cword = *vrow++;
 128                 k = 0;
 129             }
 130
 131             if (cword & (1 << k))
 132             {
 133                 rp = derives[j];
 134                 while ((rule = *rp++) >= 0)
 135                 {
 136                     SETBIT(rrow, rule);
 137                 }
 138             }
 139         }
 140
 141         vrow += varsetsize;
 142         rrow += rulesetsize;
 143     }
 144
 145 #ifdef  DEBUG
 146     print_first_derives();
 147 #endif
 148
 149     FREE(EFF);
 150 }
 151
 152
 153 void
 154 closure(short *nucleus, int n)
 155 {
 156     int ruleno;
 157     unsigned word;
 158     unsigned i;
 159     short *csp;
 160     unsigned *dsp;
 161     unsigned *rsp;
 162     int rulesetsize;
 163
 164     short *csend;
 165     unsigned *rsend;
 166     int symbol;
 167     int itemno;
 168
 169     rulesetsize = WORDSIZE(nrules);
 170     rsp = ruleset;
 171     rsend = ruleset + rulesetsize;
 172     for (rsp = ruleset; rsp < rsend; rsp++)
 173         *rsp = 0;
 174
 175     csend = nucleus + n;
 176     for (csp = nucleus; csp < csend; ++csp)
 177     {
 178         symbol = ritem[*csp];
 179         if (ISVAR(symbol))
 180         {
 181             dsp = first_derives + symbol * rulesetsize;
 182             rsp = ruleset;
 183             while (rsp < rsend)
 184                 *rsp++ |= *dsp++;
 185         }
 186     }
 187
 188     ruleno = 0;
 189     itemsetend = itemset;
 190     csp = nucleus;
 191     for (rsp = ruleset; rsp < rsend; ++rsp)
 192     {
 193         word = *rsp;
 194         if (word)
 195         {
 196             for (i = 0; i < BITS_PER_WORD; ++i)
 197             {
 198                 if (word & (1 << i))
 199                 {
 200                     itemno = rrhs[ruleno+i];
 201                     while (csp < csend && *csp < itemno)
 202                         *itemsetend++ = *csp++;
 203                     *itemsetend++ = itemno;
 204                     while (csp < csend && *csp == itemno)
 205                         ++csp;
 206                 }
 207             }
 208         }
 209         ruleno += BITS_PER_WORD;
 210     }
 211
 212     while (csp < csend)
 213         *itemsetend++ = *csp++;
 214
 215 #ifdef  DEBUG
 216   print_closure(n);
 217 #endif
 218 }
 219
 220
 221
 222 void
 223 finalize_closure(void)
 224 {
 225   FREE(itemset);
 226   FREE(ruleset);
 227   FREE(first_derives + ntokens * WORDSIZE(nrules));
 228 }
 229
 230
 231 #ifdef  DEBUG
 232
 233 static void
 234 print_closure(int n)
 235 {
 236   short *isp;
 237
 238   printf("\n\nn = %d\n\n", n);
 239   for (isp = itemset; isp < itemsetend; isp++)
 240     printf("   %d\n", *isp);
 241 }
 242
 243
 244 static void
 245 print_EFF(void)
 246 {
 247     int i, j;
 248     unsigned *rowp;
 249     unsigned word;
 250     unsigned k;
 251
 252     printf("\n\nEpsilon Free Firsts\n");
 253
 254     for (i = start_symbol; i < nsyms; i++)
 255     {
 256         printf("\n%s", symbol_name[i]);
 257         rowp = EFF + ((i - start_symbol) * WORDSIZE(nvars));
 258         word = *rowp++;
 259
 260         k = BITS_PER_WORD;
 261         for (j = 0; j < nvars; k++, j++)
 262         {
 263             if (k >= BITS_PER_WORD)
 264             {
 265                 word = *rowp++;
 266                 k = 0;
 267             }
 268
 269             if (word & (1 << k))
 270                 printf("  %s", symbol_name[start_symbol + j]);
 271         }
 272     }
 273 }
 274
 275
 276 static void
 277 print_first_derives(void)
 278 {
 279     int i;
 280     int j;
 281     unsigned *rp;
 282     unsigned cword;
 283     unsigned k;
 284
 285     printf("\n\n\nFirst Derives\n");
 286
 287     for (i = start_symbol; i < nsyms; i++)
 288     {
 289         printf("\n%s derives\n", symbol_name[i]);
 290         rp = first_derives + i * WORDSIZE(nrules);
 291         k = BITS_PER_WORD;
 292         for (j = 0; j <= nrules; k++, j++)
 293         {
 294           if (k >= BITS_PER_WORD)
 295           {
 296               cword = *rp++;
 297               k = 0;
 298           }
 299
 300           if (cword & (1 << k))
 301             printf("   %d\n", j);
 302         }
 303     }
 304
 305   fflush(stdout);
 306 }
 307
 308 #endif