138 lines
2.5 KiB
C
138 lines
2.5 KiB
C
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/* Copyright (c) 1985 Ceriel J.H. Jacobs */
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# ifndef lint
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static char rcsid[] = "$Header$";
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# endif
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# define _MACHINE_
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# include <ctype.h>
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# include "in_all.h"
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# include "machine.h"
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# include "getline.h"
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# include "assert.h"
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/*
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* Add part of finite state machine to recognize the string s.
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*/
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STATIC int
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addtomach(s, cnt, list) char *s; struct state **list; {
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register struct state *l;
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register int i = FSM_OKE; /* Return value */
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register int j;
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for (;;) {
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l = *list;
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if (!l) {
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/*
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* Create new list element
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*/
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*list = l = (struct state *) alloc(sizeof(*l), 0);
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l->s_char = *s;
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l->s_endstate = 0;
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l->s_match = 0;
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l->s_next = 0;
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}
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if (l->s_char == *s) {
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/*
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* Continue with next character
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*/
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if (!*++s) {
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/*
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* No next character
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*/
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j = l->s_endstate;
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l->s_endstate = 1;
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if (l->s_match || j) {
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/*
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* If the state already was an endstate,
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* or has a successor, the currently
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* added string is a prefix of an
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* already recognized string
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*/
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return FSM_ISPREFIX;
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}
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l->s_cnt = cnt;
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return i;
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}
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if (l->s_endstate) {
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/*
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* In this case, the currently added string has
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* a prefix that is an already recognized
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* string.
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*/
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i = FSM_HASPREFIX;
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}
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list = &(l->s_match);
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continue;
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}
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list = &(l->s_next);
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}
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/* NOTREACHED */
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}
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/*
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* Add a string to the FSM.
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*/
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int
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addstring(s,cnt,machine) register char *s; struct state **machine; {
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if (!s || !*s) {
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return FSM_ISPREFIX;
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}
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return addtomach(s,cnt,machine);
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}
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/*
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* Match string s with the finite state machine.
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* If it matches, the number of characters actually matched is returned,
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* and the count is put in the word pointed to by i.
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* If the string is a prefix of a string that could be matched,
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* FSM_ISPREFIX is returned. Otherwise, 0 is returned.
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*/
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int
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match(s,i,mach) char *s; int *i; register struct state *mach; {
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register char *s1 = s; /* Walk through string */
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register struct state *mach1 = 0;
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/* Keep track of previous state */
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while (mach && *s1) {
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if (mach->s_char == *s1) {
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/*
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* Current character matches. Carry on with next
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* character and next state
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*/
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mach1 = mach;
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mach = mach->s_match;
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s1++;
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continue;
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}
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mach = mach->s_next;
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}
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if (!mach1) {
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/*
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* No characters matched
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*/
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return 0;
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}
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if (mach1->s_endstate) {
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/*
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* The string matched
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*/
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*i = mach1->s_cnt;
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return s1 - s;
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}
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if (!*s1) {
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/*
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* The string matched a prefix
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*/
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return FSM_ISPREFIX;
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}
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return 0;
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}
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