source: vendor/flex/2.5.33/ecs.c@ 3452

/* ecs - equivalence class routines */

/*  Copyright (c) 1990 The Regents of the University of California. */
/*  All rights reserved. */

/*  This code is derived from software contributed to Berkeley by */
/*  Vern Paxson. */

/*  The United States Government has rights in this work pursuant */
/*  to contract no. DE-AC03-76SF00098 between the United States */
/*  Department of Energy and the University of California. */

/* This file is part of flex */

/*  Redistribution and use in source and binary forms, with or without */
/*  modification, are permitted provided that the following conditions */
/*  are met: */

/*  1. Redistributions of source code must retain the above copyright */
/*     notice, this list of conditions and the following disclaimer. */
/*  2. Redistributions in binary form must reproduce the above copyright */
/*     notice, this list of conditions and the following disclaimer in the */
/*     documentation and/or other materials provided with the distribution. */

/*  Neither the name of the University nor the names of its contributors */
/*  may be used to endorse or promote products derived from this software */
/*  without specific prior written permission. */

/*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
/*  IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
/*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
/*  PURPOSE. */


#include "flexdef.h"

/* ccl2ecl - convert character classes to set of equivalence classes */

void    ccl2ecl ()
{
        int     i, ich, newlen, cclp, ccls, cclmec;

        for (i = 1; i <= lastccl; ++i) {
                /* We loop through each character class, and for each character
                 * in the class, add the character's equivalence class to the
                 * new "character" class we are creating.  Thus when we are all
                 * done, character classes will really consist of collections
                 * of equivalence classes
                 */

                newlen = 0;
                cclp = cclmap[i];

                for (ccls = 0; ccls < ccllen[i]; ++ccls) {
                        ich = ccltbl[cclp + ccls];
                        cclmec = ecgroup[ich];

                        if (cclmec > 0) {
                                ccltbl[cclp + newlen] = cclmec;
                                ++newlen;
                        }
                }

                ccllen[i] = newlen;
        }
}


/* cre8ecs - associate equivalence class numbers with class members
 *
 * fwd is the forward linked-list of equivalence class members.  bck
 * is the backward linked-list, and num is the number of class members.
 *
 * Returned is the number of classes.
 */

int     cre8ecs (fwd, bck, num)
     int     fwd[], bck[], num;
{
        int     i, j, numcl;

        numcl = 0;

        /* Create equivalence class numbers.  From now on, ABS( bck(x) )
         * is the equivalence class number for object x.  If bck(x)
         * is positive, then x is the representative of its equivalence
         * class.
         */
        for (i = 1; i <= num; ++i)
                if (bck[i] == NIL) {
                        bck[i] = ++numcl;
                        for (j = fwd[i]; j != NIL; j = fwd[j])
                                bck[j] = -numcl;
                }

        return numcl;
}


/* mkeccl - update equivalence classes based on character class xtions
 *
 * synopsis
 *    Char ccls[];
 *    int lenccl, fwd[llsiz], bck[llsiz], llsiz, NUL_mapping;
 *    void mkeccl( Char ccls[], int lenccl, int fwd[llsiz], int bck[llsiz],
 *                      int llsiz, int NUL_mapping );
 *
 * ccls contains the elements of the character class, lenccl is the
 * number of elements in the ccl, fwd is the forward link-list of equivalent
 * characters, bck is the backward link-list, and llsiz size of the link-list.
 *
 * NUL_mapping is the value which NUL (0) should be mapped to.
 */

void    mkeccl (ccls, lenccl, fwd, bck, llsiz, NUL_mapping)
     Char    ccls[];
     int     lenccl, fwd[], bck[], llsiz, NUL_mapping;
{
        int     cclp, oldec, newec;
        int     cclm, i, j;
        static unsigned char cclflags[CSIZE];   /* initialized to all '\0' */

        /* Note that it doesn't matter whether or not the character class is
         * negated.  The same results will be obtained in either case.
         */

        cclp = 0;

        while (cclp < lenccl) {
                cclm = ccls[cclp];

                if (NUL_mapping && cclm == 0)
                        cclm = NUL_mapping;

                oldec = bck[cclm];
                newec = cclm;

                j = cclp + 1;

                for (i = fwd[cclm]; i != NIL && i <= llsiz; i = fwd[i]) {       /* look for the symbol in the character class */
                        for (; j < lenccl; ++j) {
                                register int ccl_char;

                                if (NUL_mapping && ccls[j] == 0)
                                        ccl_char = NUL_mapping;
                                else
                                        ccl_char = ccls[j];

                                if (ccl_char > i)
                                        break;

                                if (ccl_char == i && !cclflags[j]) {
                                        /* We found an old companion of cclm
                                         * in the ccl.  Link it into the new
                                         * equivalence class and flag it as
                                         * having been processed.
                                         */

                                        bck[i] = newec;
                                        fwd[newec] = i;
                                        newec = i;
                                        /* Set flag so we don't reprocess. */
                                        cclflags[j] = 1;

                                        /* Get next equivalence class member. */
                                        /* continue 2 */
                                        goto next_pt;
                                }
                        }

                        /* Symbol isn't in character class.  Put it in the old
                         * equivalence class.
                         */

                        bck[i] = oldec;

                        if (oldec != NIL)
                                fwd[oldec] = i;

                        oldec = i;

                      next_pt:;
                }

                if (bck[cclm] != NIL || oldec != bck[cclm]) {
                        bck[cclm] = NIL;
                        fwd[oldec] = NIL;
                }

                fwd[newec] = NIL;

                /* Find next ccl member to process. */

                for (++cclp; cclflags[cclp] && cclp < lenccl; ++cclp) {
                        /* Reset "doesn't need processing" flag. */
                        cclflags[cclp] = 0;
                }
        }
}


/* mkechar - create equivalence class for single character */

void    mkechar (tch, fwd, bck)
     int     tch, fwd[], bck[];
{
        /* If until now the character has been a proper subset of
         * an equivalence class, break it away to create a new ec
         */

        if (fwd[tch] != NIL)
                bck[fwd[tch]] = bck[tch];

        if (bck[tch] != NIL)
                fwd[bck[tch]] = fwd[tch];

        fwd[tch] = NIL;
        bck[tch] = NIL;
}