/* Warth's recursion. Hi Alessandro! */
HParseResult* h_do_parse(const HParser* parser, HParseState *state) {
HParserCacheKey *key = a_new(HParserCacheKey, 1);
key->input_pos = state->input_stream; key->parser = parser;
HParserCacheValue *m = recall(key, state);
// check to see if there is already a result for this object...
if (!m) {
// It doesn't exist, so create a dummy result to cache
HLeftRec *base = a_new(HLeftRec, 1);
base->seed = NULL; base->rule = parser; base->head = NULL;
h_slist_push(state->lr_stack, base);
// cache it
h_hashtable_put(state->cache, key, cached_lr(state, base));
// parse the input
HParseResult *tmp_res = perform_lowlevel_parse(state, parser);
// the base variable has passed equality tests with the cache
h_slist_pop(state->lr_stack);
// update the cached value to our new position
HParserCacheValue *cached = h_hashtable_get(state->cache, key);
assert(cached != NULL);
cached->input_stream = state->input_stream;
// setupLR, used below, mutates the LR to have a head if appropriate, so we check to see if we have one
if (NULL == base->head) {
h_hashtable_put(state->cache, key, cached_result(state, tmp_res));
return tmp_res;
} else {
base->seed = tmp_res;
HParseResult *res = lr_answer(key, state, base);
return res;
}
} else {
// it exists!
state->input_stream = m->input_stream;
if (PC_LEFT == m->value_type) {
setupLR(parser, state, m->left);
return m->left->seed;
} else {
return m->right;
}
}
}
void h_slist_free(HSlist *slist) {
while (slist->head != NULL)
h_slist_pop(slist);
h_arena_free(slist->arena, slist);
}
