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py: Fix bug in map lookup of interned string vs non-interned. 

Had choice of either interning or forcing full equality comparison, and
chose latter.  See comments in mp_map_lookup.

Addresses issue #523.
store-consts
Damien George 2014-04-28 12:11:57 +01:00
parent 185f9c1c46
commit 186e463a9e
2 changed files with 37 additions and 2 deletions
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24
py/map.c
View File

@ -98,13 +98,33 @@ STATIC void mp_map_rehash(mp_map_t *map) {
// MP_MAP_LOOKUP_REMOVE_IF_FOUND behaviour:
// - returns NULL if not found, else the slot if was found in with key null and value non-null
mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t lookup_kind) {
// Work out if we can compare just pointers
bool compare_only_ptrs = map->all_keys_are_qstrs;
if (compare_only_ptrs) {
if (MP_OBJ_IS_QSTR(index)) {
// Index is a qstr, so can just do ptr comparison.
} else if (MP_OBJ_IS_TYPE(index, &mp_type_str)) {
// Index is a non-interned string.
// We can either intern the string, or force a full equality comparison.
// We chose the latter, since interning costs time and potentially RAM,
// and it won't necessarily benefit subsequent calls because these calls
// most likely won't pass the newly-interned string.
compare_only_ptrs = false;
} else if (!(lookup_kind & MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)) {
// If we are not adding, then we can return straight away a failed
// lookup because we know that the index will never be found.
return NULL;
}
}
// if the map is a fixed array then we must do a brute force linear search
if (map->table_is_fixed_array) {
if (lookup_kind != MP_MAP_LOOKUP) {
return NULL;
}
for (mp_map_elem_t *elem = &map->table[0], *top = &map->table[map->used]; elem < top; elem++) {
if (elem->key == index || (!map->all_keys_are_qstrs && mp_obj_equal(elem->key, index))) {
if (elem->key == index || (!compare_only_ptrs && mp_obj_equal(elem->key, index))) {
return elem;
}
}
@ -148,7 +168,7 @@ mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t
if (avail_slot == NULL) {
avail_slot = slot;
}
} else if (slot->key == index || (!map->all_keys_are_qstrs && mp_obj_equal(slot->key, index))) {
} else if (slot->key == index || (!compare_only_ptrs && mp_obj_equal(slot->key, index))) {
// found index
// Note: CPython does not replace the index; try x={True:'true'};x[1]='one';x
if (lookup_kind & MP_MAP_LOOKUP_REMOVE_IF_FOUND) {

15
tests/basics/dict-intern.py 100644
View File

@ -0,0 +1,15 @@
# check that interned strings are compared against non-interned strings
di = {"key1": "value"}
# lookup interned string
k = "key1"
print(k in di)
# lookup non-interned string
k2 = "key" + "1"
print(k == k2)
print(k2 in di)
# lookup non-interned string
print("".join(['k', 'e', 'y', '1']) in di)