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/usr.bin/lex/ecs.c

https://bitbucket.org/freebsd/freebsd-head/
C | 227 lines | 101 code | 46 blank | 80 comment | 35 complexity | 53299ed6472878c14ec1ee56f73754ec MD5 | raw file
  1/* ecs - equivalence class routines */
  2
  3/*-
  4 * Copyright (c) 1990 The Regents of the University of California.
  5 * All rights reserved.
  6 *
  7 * This code is derived from software contributed to Berkeley by
  8 * Vern Paxson.
  9 * 
 10 * The United States Government has rights in this work pursuant
 11 * to contract no. DE-AC03-76SF00098 between the United States
 12 * Department of Energy and the University of California.
 13 *
 14 * Redistribution and use in source and binary forms are permitted provided
 15 * that: (1) source distributions retain this entire copyright notice and
 16 * comment, and (2) distributions including binaries display the following
 17 * acknowledgement:  ``This product includes software developed by the
 18 * University of California, Berkeley and its contributors'' in the
 19 * documentation or other materials provided with the distribution and in
 20 * all advertising materials mentioning features or use of this software.
 21 * Neither the name of the University nor the names of its contributors may
 22 * be used to endorse or promote products derived from this software without
 23 * specific prior written permission.
 24 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 25 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 27 */
 28
 29/* $Header: /home/daffy/u0/vern/flex/RCS/ecs.c,v 2.9 93/12/07 10:18:20 vern Exp $ */
 30#include <sys/cdefs.h>
 31__FBSDID("$FreeBSD$");
 32
 33#include "flexdef.h"
 34
 35/* ccl2ecl - convert character classes to set of equivalence classes */
 36
 37void ccl2ecl()
 38	{
 39	int i, ich, newlen, cclp, ccls, cclmec;
 40
 41	for ( i = 1; i <= lastccl; ++i )
 42		{
 43		/* We loop through each character class, and for each character
 44		 * in the class, add the character's equivalence class to the
 45		 * new "character" class we are creating.  Thus when we are all
 46		 * done, character classes will really consist of collections
 47		 * of equivalence classes
 48		 */
 49
 50		newlen = 0;
 51		cclp = cclmap[i];
 52
 53		for ( ccls = 0; ccls < ccllen[i]; ++ccls )
 54			{
 55			ich = ccltbl[cclp + ccls];
 56			cclmec = ecgroup[ich];
 57
 58			if ( cclmec > 0 )
 59				{
 60				ccltbl[cclp + newlen] = cclmec;
 61				++newlen;
 62				}
 63			}
 64
 65		ccllen[i] = newlen;
 66		}
 67	}
 68
 69
 70/* cre8ecs - associate equivalence class numbers with class members
 71 *
 72 * fwd is the forward linked-list of equivalence class members.  bck
 73 * is the backward linked-list, and num is the number of class members.
 74 *
 75 * Returned is the number of classes.
 76 */
 77
 78int cre8ecs( fwd, bck, num )
 79int fwd[], bck[], num;
 80	{
 81	int i, j, numcl;
 82
 83	numcl = 0;
 84
 85	/* Create equivalence class numbers.  From now on, ABS( bck(x) )
 86	 * is the equivalence class number for object x.  If bck(x)
 87	 * is positive, then x is the representative of its equivalence
 88	 * class.
 89	 */
 90	for ( i = 1; i <= num; ++i )
 91		if ( bck[i] == NIL )
 92			{
 93			bck[i] = ++numcl;
 94			for ( j = fwd[i]; j != NIL; j = fwd[j] )
 95				bck[j] = -numcl;
 96			}
 97
 98	return numcl;
 99	}
100
101
102/* mkeccl - update equivalence classes based on character class xtions
103 *
104 * synopsis
105 *    Char ccls[];
106 *    int lenccl, fwd[llsiz], bck[llsiz], llsiz, NUL_mapping;
107 *    void mkeccl( Char ccls[], int lenccl, int fwd[llsiz], int bck[llsiz],
108 *			int llsiz, int NUL_mapping );
109 *
110 * ccls contains the elements of the character class, lenccl is the
111 * number of elements in the ccl, fwd is the forward link-list of equivalent
112 * characters, bck is the backward link-list, and llsiz size of the link-list.
113 *
114 * NUL_mapping is the value which NUL (0) should be mapped to.
115 */
116
117void mkeccl( ccls, lenccl, fwd, bck, llsiz, NUL_mapping )
118Char ccls[];
119int lenccl, fwd[], bck[], llsiz, NUL_mapping;
120	{
121	int cclp, oldec, newec;
122	int cclm, i, j;
123	static unsigned char cclflags[CSIZE];	/* initialized to all '\0' */
124
125	/* Note that it doesn't matter whether or not the character class is
126	 * negated.  The same results will be obtained in either case.
127	 */
128
129	cclp = 0;
130
131	while ( cclp < lenccl )
132		{
133		cclm = ccls[cclp];
134
135		if ( NUL_mapping && cclm == 0 )
136			cclm = NUL_mapping;
137
138		oldec = bck[cclm];
139		newec = cclm;
140
141		j = cclp + 1;
142
143		for ( i = fwd[cclm]; i != NIL && i <= llsiz; i = fwd[i] )
144			{ /* look for the symbol in the character class */
145			for ( ; j < lenccl; ++j )
146				{
147				int ccl_char;
148
149				if ( NUL_mapping && ccls[j] == 0 )
150					ccl_char = NUL_mapping;
151				else
152					ccl_char = ccls[j];
153
154				if ( ccl_char > i )
155					break;
156
157				if ( ccl_char == i && ! cclflags[j] )
158					{
159					/* We found an old companion of cclm
160					 * in the ccl.  Link it into the new
161					 * equivalence class and flag it as
162					 * having been processed.
163					 */
164
165					bck[i] = newec;
166					fwd[newec] = i;
167					newec = i;
168					/* Set flag so we don't reprocess. */
169					cclflags[j] = 1;
170
171					/* Get next equivalence class member. */
172					/* continue 2 */
173					goto next_pt;
174					}
175				}
176
177			/* Symbol isn't in character class.  Put it in the old
178			 * equivalence class.
179			 */
180
181			bck[i] = oldec;
182
183			if ( oldec != NIL )
184				fwd[oldec] = i;
185
186			oldec = i;
187
188			next_pt: ;
189			}
190
191		if ( bck[cclm] != NIL || oldec != bck[cclm] )
192			{
193			bck[cclm] = NIL;
194			fwd[oldec] = NIL;
195			}
196
197		fwd[newec] = NIL;
198
199		/* Find next ccl member to process. */
200
201		for ( ++cclp; cclflags[cclp] && cclp < lenccl; ++cclp )
202			{
203			/* Reset "doesn't need processing" flag. */
204			cclflags[cclp] = 0;
205			}
206		}
207	}
208
209
210/* mkechar - create equivalence class for single character */
211
212void mkechar( tch, fwd, bck )
213int tch, fwd[], bck[];
214	{
215	/* If until now the character has been a proper subset of
216	 * an equivalence class, break it away to create a new ec
217	 */
218
219	if ( fwd[tch] != NIL )
220		bck[fwd[tch]] = bck[tch];
221
222	if ( bck[tch] != NIL )
223		fwd[bck[tch]] = fwd[tch];
224
225	fwd[tch] = NIL;
226	bck[tch] = NIL;
227	}