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Diffstat (limited to 'src/ecs.c')
| -rw-r--r-- | src/ecs.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/src/ecs.c b/src/ecs.c new file mode 100644 index 0000000..b2afc1f --- /dev/null +++ b/src/ecs.c @@ -0,0 +1,215 @@ +/* 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 (void) +{ + 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 (int fwd[], int bck[], int 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 + * unsigned char ccls[]; + * int lenccl, fwd[llsiz], bck[llsiz], llsiz, NUL_mapping; + * void mkeccl( unsigned 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 (unsigned char ccls[], int lenccl, int fwd[], int bck[], int llsiz, int 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) { + 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; cclp < lenccl && cclflags[cclp]; ++cclp) { + /* Reset "doesn't need processing" flag. */ + cclflags[cclp] = 0; + } + } +} + + +/* mkechar - create equivalence class for single character */ + +void mkechar (int tch, int fwd[], int 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; +} |