/**
* Remove unuseful failure links to skip using an invalid transition
*
* @param ac_tree the matcher that holds the patterns
* @param state the state where it should start (it's used recursively)
*
*/
static void ib_ac_unlink_unuseful(ib_ac_t *ac_tree,
ib_ac_state_t *state)
{
IB_FTRACE_INIT();
ib_ac_state_t *child = NULL;
ib_ac_state_t *fail_state = NULL;
ib_ac_state_t *found = NULL;
for (child = state->child;
child != NULL;
child = child->sibling)
{
if (child->fail == NULL ||
child->fail->child == NULL ||
child->child == NULL)
{
continue;
}
for (fail_state = child->fail->child;
fail_state != ac_tree->root && fail_state != NULL;
fail_state = fail_state->sibling)
{
found = ib_ac_child_for_code(child, fail_state->letter);
if (found == NULL) {
break;
}
}
if (found != NULL) {
/* There's no transition in the fail state that will
* success, since the fail state doesn't have any letter not
* present at the goto() of the main state. So let's
* change the fail state to parent. Consider that this is
* different to the output links (they'll still valid) */
child->fail = ac_tree->root;
/* printf("Removing invalid fails\n"); */
}
}
for (child = state->child;
child != NULL;
child = child->sibling)
{
if (child->child != NULL) {
ib_ac_unlink_unuseful(ac_tree, child);
}
}
IB_FTRACE_RET_VOID();
}
/**
* Constructs fail links of branches (the failure transition function)
*
* @param ac_tree the ac tree matcher
*
* @return ib_status_t status of the operation
*/
static ib_status_t ib_ac_link_fail_states(ib_ac_t *ac_tree)
{
ib_status_t rc;
ib_ac_state_t *child = NULL;
ib_ac_state_t *state = NULL;
ib_ac_state_t *goto_state = NULL;
ib_list_t *iter_queue = NULL;
if (ac_tree->flags & IB_AC_FLAG_PARSER_COMPILED) {
return IB_OK;
}
ac_tree->root->pattern = 0;
rc = ib_list_create(&iter_queue, ac_tree->mp);
if (rc != IB_OK) {
return rc;
}
ac_tree->root->fail = ac_tree->root;
/* All first-level children will fail back to root state */
for (child = ac_tree->root->child;
child != NULL;
child = child->sibling)
{
child->fail = ac_tree->root;
rc = ib_list_enqueue(iter_queue, (void *) child);
if (rc != IB_OK) {
return rc;
}
}
while (ib_list_elements(iter_queue) > 0) {
rc = ib_list_dequeue(iter_queue, (void *) &state);
if (rc != IB_OK) {
return rc;
}
state->fail = ac_tree->root;
if (state->parent != ac_tree->root) {
goto_state = ib_ac_child_for_code(state->parent->fail,
state->letter);
if (goto_state != NULL) {
state->fail = goto_state;
}
}
for (child = state->child;
child != NULL;
child = child->sibling)
{
rc = ib_list_enqueue(iter_queue, (void *) child);
if (rc != IB_OK) {
return rc;
}
}
}
/* Link common outputs of subpatterns present in the branch*/
ib_ac_link_outputs(ac_tree, ac_tree->root);
/* Unlink invalid fail transitions. This guarantees that there will
* be at least one letter with transition in each fail state*/
ib_ac_unlink_unuseful(ac_tree, ac_tree->root);
if (ac_tree->root->child != NULL) {
ib_ac_build_bintree(ac_tree, ac_tree->root);
}
ac_tree->flags |= IB_AC_FLAG_PARSER_COMPILED;
return IB_OK;
}