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Annotation of researchv10dc/cmd/bison/derives.c, revision 1.1

1.1     ! root        1: /* Match rules with nonterminals for bison,
        !             2:    Copyright (C) 1984 Bob Corbett and Free Software Foundation, Inc.
        !             3: 
        !             4: BISON is distributed in the hope that it will be useful, but WITHOUT ANY
        !             5: WARRANTY.  No author or distributor accepts responsibility to anyone
        !             6: for the consequences of using it or for whether it serves any
        !             7: particular purpose or works at all, unless he says so in writing.
        !             8: Refer to the BISON General Public License for full details.
        !             9: 
        !            10: Everyone is granted permission to copy, modify and redistribute BISON,
        !            11: but only under the conditions described in the BISON General Public
        !            12: License.  A copy of this license is supposed to have been given to you
        !            13: along with BISON so you can know your rights and responsibilities.  It
        !            14: should be in a file named COPYING.  Among other things, the copyright
        !            15: notice and this notice must be preserved on all copies.
        !            16: 
        !            17:  In other words, you are welcome to use, share and improve this program.
        !            18:  You are forbidden to forbid anyone else to use, share and improve
        !            19:  what you give them.   Help stamp out software-hoarding!  */
        !            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, terminated with a zero.  */
        !            24: 
        !            25: #include <stdio.h>
        !            26: #include "new.h"
        !            27: #include "types.h"
        !            28: #include "gram.h"
        !            29: 
        !            30: 
        !            31: short **derives;
        !            32: 
        !            33: 
        !            34: set_derives()
        !            35: {
        !            36:   register int i;
        !            37:   register int lhs;
        !            38:   register shorts *p;
        !            39:   register short *q;
        !            40:   register shorts **dset;
        !            41:   register shorts *delts;
        !            42: 
        !            43:   dset = NEW2(nvars, shorts *) - ntokens;
        !            44:   delts = NEW2(nrules + 1, shorts);
        !            45: 
        !            46:   p = delts;
        !            47:   for (i = nrules; i > 0; i--)
        !            48:     {
        !            49:       lhs = rlhs[i];
        !            50:       p->next = dset[lhs];
        !            51:       p->value = i;
        !            52:       dset[lhs] = p;
        !            53:       p++;
        !            54:     }
        !            55: 
        !            56:   derives = NEW2(nvars, short *) - ntokens;
        !            57:   q = NEW2(nvars + nrules, short);
        !            58: 
        !            59:   for (i = ntokens; i < nsyms; i++)
        !            60:     {
        !            61:       derives[i] = q;
        !            62:       p = dset[i];
        !            63:       while (p)
        !            64:        {
        !            65:          *q++ = p->value;
        !            66:          p = p->next;
        !            67:        }
        !            68:       *q++ = -1;
        !            69:     }
        !            70: 
        !            71: #ifdef DEBUG
        !            72:   print_derives();
        !            73: #endif
        !            74: 
        !            75:   FREE(dset + ntokens);
        !            76:   FREE(delts);
        !            77: }
        !            78: 
        !            79: 
        !            80: free_derives()
        !            81: {
        !            82:   FREE(derives[ntokens]);
        !            83:   FREE(derives + ntokens);
        !            84: }
        !            85: 
        !            86: 
        !            87: 
        !            88: #ifdef DEBUG
        !            89: 
        !            90: print_derives()
        !            91: {
        !            92:   register int i;
        !            93:   register short *sp;
        !            94: 
        !            95:   extern char **tags;
        !            96: 
        !            97:   printf("\n\n\nDERIVES\n\n");
        !            98: 
        !            99:   for (i = ntokens; i < nsyms; i++)
        !           100:     {
        !           101:       printf("%s derives", tags[i]);
        !           102:       for (sp = derives[i]; *sp > 0; sp++)
        !           103:        {
        !           104:          printf("  %d", *sp);
        !           105:        }
        !           106:       putchar('\n');
        !           107:     }
        !           108: 
        !           109:   putchar('\n');
        !           110: }
        !           111: 
        !           112: #endif
        !           113: 

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