Implement construction of regular expression NFAs.
This commit is contained in:
parent
a2044b596a
commit
06fe67b226
298
src/libregex.c
298
src/libregex.c
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@ -3,6 +3,11 @@
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#include <string.h>
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#include "ll.h"
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int _regex_node_foreach_free(void* data, va_list args){
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free(data);
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return 0;
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}
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libregex_result _regex_node_create_clear(regex_node** node){
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libregex_result result = LIBREGEX_SUCCESS;
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*node = malloc(sizeof(**node));
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@ -175,8 +180,301 @@ libregex_result _regex_find_all(regex_node* node, ll* append_to, int tag_with){
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return result;
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}
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libregex_result _regex_read_value(char* read_into, char* expression, int* string_index){
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libregex_result result = LIBREGEX_SUCCESS;
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if(expression[*string_index] == '\\'){
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(*string_index)++;
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}
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if(expression[*string_index]){
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*read_into = expression[*string_index];
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(*string_index)++;
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} else {
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*read_into = '\0';
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result = LIBREGEX_INVALID;
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}
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return result;
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}
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libregex_result _regex_build_or(regex_chain** build_into, char* expression, int* string_index){
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regex_node* tail_node = NULL;
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libregex_result result = _regex_chain_create(build_into, NULL, NULL);
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if(result == LIBREGEX_SUCCESS){
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_regex_node_create_connect(&tail_node, NULL);
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_regex_chain_append_node(*build_into, tail_node);
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(*string_index)++;
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}
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while(result == LIBREGEX_SUCCESS && expression[*string_index] && expression[*string_index] != ']'){
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regex_node* new_node = NULL;
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regex_node* fork = NULL;
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regex_node* new_head = NULL;
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char from = '\0';
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char to = '\0';
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result = _regex_read_value(&from, expression, string_index);
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if(result == LIBREGEX_SUCCESS){
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if(expression[*string_index] == '-'){
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(*string_index)++;
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result = _regex_read_value(&to, expression, string_index);
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}
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}
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if(result == LIBREGEX_SUCCESS){
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result = (to == '\0') ? _regex_node_create_value(&new_node, from, tail_node) :
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_regex_node_create_range(&new_node, from, to, tail_node);
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new_head = new_node;
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}
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if(result == LIBREGEX_SUCCESS && (*build_into)->head != tail_node){
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result = _regex_node_create_fork(&fork, (*build_into)->head, new_node);
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new_head = fork;
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}
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if(result == LIBREGEX_SUCCESS){
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(*build_into)->head = new_head;
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} else {
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free(fork);
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free(new_head);
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}
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}
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if(result == LIBREGEX_SUCCESS){
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if(expression[*string_index] == ']'){
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(*string_index)++;
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} else {
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result = LIBREGEX_INVALID;
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}
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}
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if(result != LIBREGEX_SUCCESS){
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regex_free((*build_into)->head);
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free(*build_into);
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*build_into = NULL;
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}
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return result;
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}
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int _regex_is_char_op(char c){
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return c == '*' || c == '+' || c == '?';
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}
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void _regex_chain_merge(regex_chain** merge_into, regex_chain** to_merge){
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_regex_chain_append_chain(*merge_into, *to_merge);
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free(*to_merge);
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*to_merge = NULL;
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}
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libregex_result _regex_build_chain(regex_chain** build_into, char* expression, int* string_index, int* groups){
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regex_node* group_open = NULL;
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regex_node* group_close = NULL;
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regex_chain* current_chain = NULL;
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regex_chain* sub_chain = NULL;
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ll chain_stack;
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int is_subchain = *string_index >= 0 && expression[*string_index] == '(';
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libregex_result result = LIBREGEX_SUCCESS;
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if(is_subchain){
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result = _regex_node_create_group(&group_open, &group_close, ++(*groups));
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}
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if(result == LIBREGEX_SUCCESS){
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result = _regex_chain_create(¤t_chain, NULL, NULL);
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}
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if(result == LIBREGEX_SUCCESS){
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(*string_index)++;
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}
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ll_init(&chain_stack);
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while(expression[*string_index] && expression[*string_index] != ')' && result == LIBREGEX_SUCCESS){
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if(_regex_is_char_op(expression[*string_index])){
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if(sub_chain){
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regex_node* connect = NULL;
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regex_node* fork = NULL;
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result = _regex_node_create_connect(&connect, NULL);
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if(result == LIBREGEX_SUCCESS){
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result = _regex_node_create_fork(&fork, sub_chain->head, connect);
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}
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if(result == LIBREGEX_SUCCESS){
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if(expression[*string_index] == '+' || expression[*string_index] == '*'){
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_regex_chain_append_node(sub_chain, fork);
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if(expression[*string_index] == '*'){
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sub_chain->head = fork;
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}
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} else {
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_regex_chain_append_node(sub_chain, connect);
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sub_chain->head = fork;
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}
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sub_chain->tail = connect;
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_regex_chain_merge(¤t_chain, &sub_chain);
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(*string_index)++;
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} else {
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free(connect);
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free(fork);
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}
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} else {
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result = LIBREGEX_INVALID;
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}
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} else if(expression[*string_index] == '('){
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_regex_chain_merge(¤t_chain, &sub_chain);
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result = _regex_build_chain(&sub_chain, expression, string_index, groups);
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} else if(expression[*string_index] == '['){
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_regex_chain_merge(¤t_chain, &sub_chain);
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result = _regex_build_or(&sub_chain, expression, string_index);
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} else if(expression[*string_index] == '|'){
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_regex_chain_merge(¤t_chain, &sub_chain);
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result = ll_append(&chain_stack, current_chain) == LIBDS_SUCCESS ? LIBREGEX_SUCCESS : LIBREGEX_MALLOC;
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if(result == LIBREGEX_SUCCESS){
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result = _regex_chain_create(¤t_chain, NULL, NULL);
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}
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(*string_index)++;
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} else {
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regex_node* new_node = NULL;
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_regex_chain_merge(¤t_chain, &sub_chain);
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if(expression[*string_index] == '.'){
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result = _regex_node_create_any(&new_node, NULL);
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if(result == LIBREGEX_SUCCESS){
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(*string_index)++;
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}
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} else {
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char into = '\0';
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result = _regex_read_value(&into, expression, string_index);
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if(result == LIBREGEX_SUCCESS){
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result = _regex_node_create_value(&new_node, into, NULL);
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}
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}
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if(result == LIBREGEX_SUCCESS){
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result = _regex_chain_create(&sub_chain, new_node, new_node);
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}
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if(result != LIBREGEX_SUCCESS){
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free(new_node);
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free(sub_chain);
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sub_chain = NULL;
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}
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}
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}
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if(result == LIBREGEX_SUCCESS){
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_regex_chain_merge(¤t_chain, &sub_chain);
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} else {
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if(sub_chain){
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regex_free(sub_chain->head);
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free(sub_chain);
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sub_chain = NULL;
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}
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}
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if(result == LIBREGEX_SUCCESS && is_subchain && expression[*string_index] != ')'){
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result = LIBREGEX_INVALID;
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}
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if(result == LIBREGEX_SUCCESS && chain_stack.head){
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if(current_chain->tail){
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regex_node* end_node = NULL;
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result = _regex_node_create_connect(&end_node, NULL);
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_regex_chain_append_node(current_chain, end_node);
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while(chain_stack.tail && result == LIBREGEX_SUCCESS){
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regex_node* fork = NULL;
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regex_chain* new_chain = ll_poptail(&chain_stack);
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result = _regex_node_create_fork(&fork, current_chain->head, new_chain->head);
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if(result == LIBREGEX_SUCCESS){
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_regex_chain_append_node(new_chain, end_node);
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current_chain->head = fork;
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} else {
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if(new_chain){
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regex_free(new_chain->head);
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}
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}
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free(new_chain);
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}
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} else {
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result = LIBREGEX_INVALID;
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}
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}
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if(result == LIBREGEX_SUCCESS){
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if(is_subchain){
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(*string_index)++;
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}
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_regex_chain_append_node(current_chain, group_close);
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_regex_chain_prepend_node(current_chain, group_open);
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*build_into = current_chain;
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} else {
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while(chain_stack.tail){
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regex_chain* new_chain = ll_poptail(&chain_stack);
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if(new_chain){
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regex_free(new_chain->head);
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free(new_chain);
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}
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}
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if(current_chain){
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regex_free(current_chain->head);
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free(current_chain);
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}
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free(group_close);
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free(group_open);
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*build_into = NULL;
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}
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return result;
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}
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void regex_node_clear(regex_node* node){
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node->type = REGEX_CLEAR;
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node->list_id = -1;
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memset(&node->data_u, 0, sizeof(node->data_u));
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}
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libregex_result regex_free(regex_node* root){
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libregex_result result;
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ll found_list;
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ll_init(&found_list);
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result = _regex_find_all(root, &found_list, -2);
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ll_foreach(&found_list, NULL, compare_always, _regex_node_foreach_free);
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ll_free(&found_list);
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return result;
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}
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libregex_result regex_build(regex_node** root, char* expression){
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libregex_result result;
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regex_chain* building_chain = NULL;
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int index = -1;
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int number_groups = 0;
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regex_node* end_node = NULL;
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result = _regex_node_create_clear(&end_node);
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if(result == LIBREGEX_SUCCESS){
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end_node->type = REGEX_END;
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result = _regex_build_chain(&building_chain, expression, &index, &number_groups);
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}
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if(result == LIBREGEX_SUCCESS){
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_regex_chain_append_node(building_chain, end_node);
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*root = building_chain->head;
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free(building_chain);
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} else {
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free(end_node);
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if(building_chain){
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regex_free(building_chain->head);
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free(building_chain);
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}
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*root = NULL;
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}
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return result;
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}
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libregex_result regex_match_string(regex_node* root, char* string, regex_result* result);
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