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more leftrec fixes: head caching and input rewinding

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This commit is contained in:
Sven M. Hallberg 2014-03-21 20:54:33 +01:00
parent fbdd2b7613
commit f4afd0cb8d
2 changed files with 34 additions and 23 deletions
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56
src/backends/packrat.c
View file

@ -56,26 +56,28 @@ static inline HParseResult* perform_lowlevel_parse(HParseState *state, const HPa
HParserCacheValue* recall(HParserCacheKey *k, HParseState *state) {
HParserCacheValue *cached = h_hashtable_get(state->cache, k);
HRecursionHead *head = h_hashtable_get(state->recursion_heads, k);
HRecursionHead *head = h_hashtable_get(state->recursion_heads, &k->input_pos);
if (!head) { // No heads found
return cached;
} else { // Some heads found
if (!cached && head->head_parser != k->parser && !h_slist_find(head->involved_set, k->parser)) {
// Nothing in the cache, and the key parser is not involved
HParseResult *tmp = a_new(HParseResult, 1);
tmp->ast = NULL; tmp->arena = state->arena;
return cached_result(state, tmp);
cached = cached_result(state, NULL);
cached->input_stream = k->input_pos;
}
if (h_slist_find(head->eval_set, k->parser)) {
// Something is in the cache, and the key parser is in the eval set. Remove the key parser from the eval set of the head.
head->eval_set = h_slist_remove_all(head->eval_set, k->parser);
HParseResult *tmp_res = perform_lowlevel_parse(state, k->parser);
// we know that cached has an entry here, modify it
if (!cached)
cached = a_new(HParserCacheValue, 1);
cached->value_type = PC_RIGHT;
cached->right = tmp_res;
cached->input_stream = state->input_stream;
// update the cache
if (!cached) {
cached = cached_result(state, tmp_res);
h_hashtable_put(state->cache, k, cached);
} else {
cached->value_type = PC_RIGHT;
cached->right = tmp_res;
cached->input_stream = state->input_stream;
}
}
return cached;
}
@ -95,8 +97,6 @@ void setupLR(const HParser *p, HParseState *state, HLeftRec *rec_detect) {
rec_detect->head = some;
}
// XXX is it ok for lr_stack to be empty here?! (we used to have an assert
// saying it was not.)
HSlistNode *it;
for(it=state->lr_stack->head; it; it=it->next) {
HLeftRec *lr = it->elem;
@ -106,10 +106,7 @@ void setupLR(const HParser *p, HParseState *state, HLeftRec *rec_detect) {
lr->head = rec_detect->head;
h_slist_push(lr->head->involved_set, (void*)lr->rule);
// XXX we are assuming that involved_set does not contain p, yet,
// or ignoring that fact. is this correct?
}
//assert(it != NULL); // we should always find p (XXX unless lr_stack empty?)
}
// helper: true iff pos1 is less than pos2
@ -124,12 +121,15 @@ static inline bool pos_lt(HInputStream pos1, HInputStream pos2) {
HParseResult* grow(HParserCacheKey *k, HParseState *state, HRecursionHead *head) {
// Store the head into the recursion_heads
h_hashtable_put(state->recursion_heads, k, head);
h_hashtable_put(state->recursion_heads, &k->input_pos, head);
HParserCacheValue *old_cached = h_hashtable_get(state->cache, k);
if (!old_cached || PC_LEFT == old_cached->value_type)
errx(1, "impossible match");
HParseResult *old_res = old_cached->right;
// rewind the input
state->input_stream = k->input_pos;
// reset the eval_set of the head of the recursion at each beginning of growth
head->eval_set = h_slist_copy(head->involved_set);
HParseResult *tmp_res = perform_lowlevel_parse(state, k->parser);
@ -140,16 +140,18 @@ HParseResult* grow(HParserCacheKey *k, HParseState *state, HRecursionHead *head)
return grow(k, state, head);
} else {
// we're done with growing, we can remove data from the recursion head
h_hashtable_del(state->recursion_heads, k);
h_hashtable_del(state->recursion_heads, &k->input_pos);
HParserCacheValue *cached = h_hashtable_get(state->cache, k);
if (cached && PC_RIGHT == cached->value_type) {
state->input_stream = cached->input_stream;
return cached->right;
} else {
errx(1, "impossible match");
}
}
} else {
h_hashtable_del(state->recursion_heads, k);
h_hashtable_del(state->recursion_heads, &k->input_pos);
state->input_stream = old_cached->input_stream;
return old_res;
}
}
@ -185,13 +187,14 @@ HParseResult* h_do_parse(const HParser* parser, HParseState *state) {
base->seed = NULL; base->rule = parser; base->head = NULL;
h_slist_push(state->lr_stack, base);
// cache it
HParserCacheValue *cached = cached_lr(state, base);
h_hashtable_put(state->cache, key, cached);
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) {
@ -207,7 +210,7 @@ HParseResult* h_do_parse(const HParser* parser, HParseState *state) {
state->input_stream = m->input_stream;
if (PC_LEFT == m->value_type) {
setupLR(parser, state, m->left);
return m->left->seed; // BUG: this might not be correct
return m->left->seed;
} else {
return m->right;
}
@ -231,6 +234,14 @@ static bool cache_key_equal(const void* key1, const void* key2) {
return memcmp(key1, key2, sizeof(HParserCacheKey)) == 0;
}
static uint32_t pos_hash(const void* key) {
return h_djbhash(key, sizeof(HInputStream));
}
static bool pos_equal(const void* key1, const void* key2) {
return memcmp(key1, key2, sizeof(HInputStream)) == 0;
}
HParseResult *h_packrat_parse(HAllocator* mm__, const HParser* parser, HInputStream *input_stream) {
HArena * arena = h_new_arena(mm__, 0);
HParseState *parse_state = a_new_(arena, HParseState, 1);
@ -238,8 +249,7 @@ HParseResult *h_packrat_parse(HAllocator* mm__, const HParser* parser, HInputStr
cache_key_hash); // hash_func
parse_state->input_stream = *input_stream;
parse_state->lr_stack = h_slist_new(arena);
parse_state->recursion_heads = h_hashtable_new(arena, cache_key_equal,
cache_key_hash);
parse_state->recursion_heads = h_hashtable_new(arena, pos_equal, pos_hash);
parse_state->arena = arena;
HParseResult *res = h_do_parse(parser, parse_state);
h_slist_free(parse_state->lr_stack);

1
src/t_parser.c
View file

@ -414,6 +414,7 @@ static void test_leftrec(gconstpointer backend) {
HParser *lr_ = h_indirect();
h_bind_indirect(lr_, h_choice(h_sequence(lr_, a_, NULL), h_epsilon_p(), NULL));
g_check_parse_match(lr_, (HParserBackend)GPOINTER_TO_INT(backend), "", 0, "NULL");
g_check_parse_match(lr_, (HParserBackend)GPOINTER_TO_INT(backend), "a", 1, "(u0x61)");
g_check_parse_match(lr_, (HParserBackend)GPOINTER_TO_INT(backend), "aa", 2, "((u0x61) u0x61)");
g_check_parse_match(lr_, (HParserBackend)GPOINTER_TO_INT(backend), "aaa", 3, "(((u0x61) u0x61) u0x61)");