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Annotation of GNUtools/bison/derives.c, revision 1.1

1.1     ! root        1: /* Match rules with nonterminals for bison,
        !             2:    Copyright (C) 1984, 1989 Free Software Foundation, Inc.
        !             3: 
        !             4: This file is part of Bison, the GNU Compiler Compiler.
        !             5: 
        !             6: Bison is free software; you can redistribute it and/or modify
        !             7: it under the terms of the GNU General Public License as published by
        !             8: the Free Software Foundation; either version 2, or (at your option)
        !             9: any later version.
        !            10: 
        !            11: Bison is distributed in the hope that it will be useful,
        !            12: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            14: GNU General Public License for more details.
        !            15: 
        !            16: You should have received a copy of the GNU General Public License
        !            17: along with Bison; see the file COPYING.  If not, write to
        !            18: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            19: 
        !            20: 
        !            21: /* set_derives finds, for each variable (nonterminal), which rules can derive it.
        !            22:    It sets up the value of derives so that
        !            23:    derives[i - ntokens] points to a vector of rule numbers,
        !            24:    terminated with -1.  */
        !            25: 
        !            26: #include <stdio.h>
        !            27: #include "system.h"
        !            28: #include "new.h"
        !            29: #include "types.h"
        !            30: #include "gram.h"
        !            31: 
        !            32: 
        !            33: short **derives;
        !            34: 
        !            35: void
        !            36: set_derives()
        !            37: {
        !            38:   register int i;
        !            39:   register int lhs;
        !            40:   register shorts *p;
        !            41:   register short *q;
        !            42:   register shorts **dset;
        !            43:   register shorts *delts;
        !            44: 
        !            45:   dset = NEW2(nvars, shorts *) - ntokens;
        !            46:   delts = NEW2(nrules + 1, shorts);
        !            47: 
        !            48:   p = delts;
        !            49:   for (i = nrules; i > 0; i--)
        !            50:     {
        !            51:       lhs = rlhs[i];
        !            52:       if (lhs >= 0)
        !            53:        {
        !            54:          p->next = dset[lhs];
        !            55:          p->value = i;
        !            56:          dset[lhs] = p;
        !            57:          p++;
        !            58:        }
        !            59:     }
        !            60: 
        !            61:   derives = NEW2(nvars, short *) - ntokens;
        !            62:   q = NEW2(nvars + nrules, short);
        !            63: 
        !            64:   for (i = ntokens; i < nsyms; i++)
        !            65:     {
        !            66:       derives[i] = q;
        !            67:       p = dset[i];
        !            68:       while (p)
        !            69:        {
        !            70:          *q++ = p->value;
        !            71:          p = p->next;
        !            72:        }
        !            73:       *q++ = -1;
        !            74:     }
        !            75: 
        !            76: #ifdef DEBUG
        !            77:   print_derives();
        !            78: #endif
        !            79: 
        !            80:   FREE(dset + ntokens);
        !            81:   FREE(delts);
        !            82: }
        !            83: 
        !            84: void
        !            85: free_derives()
        !            86: {
        !            87:   FREE(derives[ntokens]);
        !            88:   FREE(derives + ntokens);
        !            89: }
        !            90: 
        !            91: 
        !            92: 
        !            93: #ifdef DEBUG
        !            94: 
        !            95: print_derives()
        !            96: {
        !            97:   register int i;
        !            98:   register short *sp;
        !            99: 
        !           100:   extern char **tags;
        !           101: 
        !           102:   printf("\n\n\nDERIVES\n\n");
        !           103: 
        !           104:   for (i = ntokens; i < nsyms; i++)
        !           105:     {
        !           106:       printf("%s derives", tags[i]);
        !           107:       for (sp = derives[i]; *sp > 0; sp++)
        !           108:        {
        !           109:          printf("  %d", *sp);
        !           110:        }
        !           111:       putchar('\n');
        !           112:     }
        !           113: 
        !           114:   putchar('\n');
        !           115: }
        !           116: 
        !           117: #endif
        !           118: 

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