86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
/*
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* Copyright (c) Camden Dixie O'Brien
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* SPDX-License-Identifier: AGPL-3.0-only
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*/
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#include "construct.h"
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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static void construct_literal(char literal, fsa_t *out)
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{
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fsa_init(out);
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const int id = fsa_add_state(out);
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fsa_add_rule(out, id, out->initial, literal);
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out->initial = id;
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}
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static void construct_term(const regex_term_t *term, fsa_t *out)
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{
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switch (term->type) {
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case REGEX_TERM_EMPTY:
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fsa_init(out);
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break;
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case REGEX_TERM_LITERAL:
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construct_literal(term->literal, out);
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break;
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case REGEX_TERM_SUBEXPR:
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return;
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case REGEX_TERM_WILDCARD:
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case REGEX_TERM_CLASS:
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assert(false);
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}
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}
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static void concat_fsas(fsa_t *base, const fsa_t *other)
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{
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const int new_count = base->count + other->count - 1;
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if (base->capacity < new_count) {
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do
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base->capacity *= 2;
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while (base->capacity < new_count);
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base->states = realloc(base->states, base->capacity);
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assert(base->states);
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}
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const int copy_size = (other->count - 1) * sizeof(fsa_state_t);
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memcpy(&base->states[base->count], &other->states[1], copy_size);
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const int id_offset = base->count - 1;
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for (int i = base->count; i < new_count; ++i) {
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fsa_state_t *state = &base->states[i];
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for (int j = 0; j < state->count; ++j) {
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if (0 == state->rules[j].next)
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state->rules[j].next = base->initial;
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else
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state->rules[j].next += id_offset;
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}
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}
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base->count = new_count;
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base->initial = other->initial + id_offset;
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free(other->states[0].rules);
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free(other->states);
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}
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static void construct_sequence(const regex_sequence_t *seq, fsa_t *out)
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{
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assert(seq->count > 0);
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fsa_t term_fsa;
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construct_term(&seq->contents[seq->count - 1], out);
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for (int i = seq->count - 2; i >= 0; --i) {
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construct_term(&seq->contents[i], &term_fsa);
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concat_fsas(out, &term_fsa);
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}
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}
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void construct(const regex_t *regex, fsa_t *out)
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{
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construct_sequence(®ex->contents[0], out);
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}
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