First workin regex engine
This commit is contained in:
PedroEdiaz
167
src/lexer.c
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167
src/lexer.c
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#include <stdlib.h>
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#include <stdio.h>
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#include "main.h"
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struct patch_list
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{
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struct rgx_nfa **ptr;
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struct patch_list *next;
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};
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struct frag
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{
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struct rgx_nfa *start;
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struct patch_list *out;
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};
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struct patch_list * append(struct patch_list * pl, struct rgx_nfa ** nfa)
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{
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struct patch_list * res, * root = pl;
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res = malloc(sizeof(struct patch_list));
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*res = (struct patch_list){nfa, NULL};
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if (pl == 0 ) {
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return res;
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}
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while (pl->next) {
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pl = pl->next;
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}
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pl->next = res;
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return root;
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}
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struct rgx_nfa * patch(struct patch_list *pl, struct rgx_nfa *to) {
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while (pl) {
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*pl->ptr = to;
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pl = pl->next;
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}
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return to;
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}
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struct rgx_nfa * mknfa(struct rgx_nfa nfa)
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{
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struct rgx_nfa * res;
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res = malloc(sizeof(struct rgx_nfa));
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*res = nfa;
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return res;
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}
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struct rgx_nfa * rgx_compile(struct rgx_nfa * l, char * s, int v) {
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struct rgx_nfa *r;
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unsigned char i=-1;
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struct frag stack[0xff], a, b;
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for(;*s; ++s)
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{
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switch(*s)
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{
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case '|':
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break;
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case '*':
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b = stack[i--];
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if (i==0xff)
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{
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r = mknfa((struct rgx_nfa){UNION, {b.start, NULL}});
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patch(b.out, r);
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stack[++i] = (struct frag){r, append(NULL, &r->node[1])};
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break;
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}
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else
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{
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a = stack[i--];
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r = mknfa((struct rgx_nfa){UNION, {b.start, NULL}});
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patch(a.out, r);
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patch(b.out, r);
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a.out = append(NULL, &r->node[1]);
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stack[++i] = a;
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break;
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}
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case '?':
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b = stack[i--];
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if (i==0xff)
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{
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r = mknfa((struct rgx_nfa){UNION, {b.start, NULL}});
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b.out = append(b.out, &r->node[1]);
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stack[++i] = (struct frag){r, b.out };
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break;
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}
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else
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{
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a = stack[i--];
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r = mknfa((struct rgx_nfa){UNION, {b.start, NULL}});
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a.out = append(b.out, &patch(a.out, r)->node[1]);
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stack[++i] = a;
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break;
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}
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case '+':
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// This implemention may cause a infinite loop that crashes.
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a = stack[i--];
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r = mknfa((struct rgx_nfa){UNION, {NULL, a.start}});
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a.out = append(NULL, &patch(a.out, r)->node[0]);
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stack[++i] = a;
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break;
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case '.':
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a.start = mknfa((struct rgx_nfa){C_ANY, {NULL}});
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a.out = append(NULL, &a.start->node[0]);
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stack[++i] = a;
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break;
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default:
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a.start = mknfa((struct rgx_nfa){RUNE, {NULL}, *s});
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a.out = append(NULL, &a.start->node[0]);
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stack[++i] = a;
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break;
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}
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}
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// Append Final
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{
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stack[++i].start = mknfa((struct rgx_nfa){FINAL, {NULL}, v});
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stack[i].out = append(NULL, &stack[i].start->node[0]);
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}
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// Collapse Stack
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while (i > 0)
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{
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struct frag to;
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to = stack[i--];
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patch(stack[i].out, to.start);
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}
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return stack[i].start;
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}
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int rgx_run(struct rgx_nfa *l, char *s) {
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while (l)
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{
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switch (l->op)
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{
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case FINAL:
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return *s ? 0: l->c;
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case C_ANY:
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if (!*(s++))
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return 0;
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l = l->node[0];
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break;
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case RUNE:
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if (*(s++) != l->c)
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return 0;
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l = l->node[0];
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break;
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case UNION:
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int res = rgx_run(l->node[0], s);
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if (res)
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return res;
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l = l->node[1];
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break;
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}
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}
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return 0;
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}
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0
src/main.c
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0
src/main.c
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9
src/main.h
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9
src/main.h
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struct rgx_nfa
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{
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enum {RUNE, C_ANY, UNION, FINAL} op;
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struct rgx_nfa *node[2];
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unsigned char c;
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};
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struct rgx_nfa * rgx_compile(struct rgx_nfa * l, char * s, int v);
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int rgx_run(struct rgx_nfa * l, char * s);
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70
src/test.c
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70
src/test.c
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#include <stdio.h>
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#include "main.h"
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struct test
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{
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char * regex;
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struct match
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{
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char * s;
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int expect;
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} matches[0xff];
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} test_suite[] =
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{
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// Basic
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{"abc", {{"a", 0},{"abc", 1}, {"abcd",0 }, {NULL}}},
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{"a.c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"acc", 1}, {"aac", 1}, {NULL}}},
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{"ab+c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 0}, {NULL}}},
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{"ab*c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 1}, {NULL}}},
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{"ab?c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 0}, {"ac", 1}, {NULL}}},
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// . Compose
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{"a..c", {{"a", 0},{"abc", 0}, {"abcd",0 }, {"acc", 0}, {"ac", 0}, {"abbc", 1}, {NULL}}},
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{"a.+c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"acc", 1}, {"ac", 0}, {"abbc", 1}, {NULL}}},
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{"a.*c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"acc", 1}, {"ac", 1}, {"abbc", 1}, {NULL}}},
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{"a.?c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"acc", 1}, {"ac", 1}, {NULL}}},
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// Equal to *
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{"ab+?c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 1}, {NULL}}},
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{"ab*?c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 1}, {NULL}}},
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{"ab?+c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"ababc", 1}, {"ac", 1}, {NULL}}},
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{"ab?*c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"ababc", 1}, {"ac", 1}, {NULL}}},
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// . Alt
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//{"a|b", {{"a", 1},{"abc", 0}, {"b", 1 }, {"ba", 0}, {NULL}}},
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{"ab??c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 0}, {"ac", 1}, {"c", 1}, {NULL}}},
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{"ab++c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 0}, {"c", 0}, {"ababc",0}, {NULL}}},
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{"ab**c", {{"a", 0},{"abc", 1}, {"abcd",0 }, {"abbc", 1}, {"ac", 1}, {"c", 1}, {"ababc",1}, {NULL}}},
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// Xd
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{"a?", {{"aaaa", 0}, {"a", 1}, {NULL}}},
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{"a*", {{"aaaa", 1}, {"a", 1}, {NULL}}},
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// REDOS
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{"a+*", {{"aaaa", 1}, {"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", 1}, {NULL}}},
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{"a*b?a*", {{"aaa", 1}, {"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaba", 1}, {NULL}}},
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{"aa*+", {{"aaaa", 1}, {NULL}}},
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{"a*+", {{"a", 1}, {NULL}}},
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} ;
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int main(void)
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{
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int i=0, j=0;
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for(i =0; i<sizeof(test_suite)/sizeof(*test_suite); ++i)
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{
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struct test t = test_suite[i];
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struct rgx_nfa * nfa;
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printf("\n\t%s\n", t.regex);
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nfa = rgx_compile(NULL, t.regex, 1);
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for( struct match * m = t.matches; m->s; ++m)
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{
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int res;
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res = rgx_run(nfa, m->s);
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printf("%s: %d %s\n", res == m->expect?"PASS":"FAIL", res, m->s);
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}
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}
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}
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