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py: Fix str.replace for case when arg 0 or 1 is empty string.

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This commit is contained in:
Damien George 2014-04-07 00:39:13 +01:00
parent 36e75aef38
commit ff715429ea
2 changed files with 38 additions and 15 deletions
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48
py/objstr.c
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@ -1106,22 +1106,31 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, uint n_args, const mp_obj_t
STATIC mp_obj_t str_replace(uint n_args, const mp_obj_t *args) {
assert(MP_OBJ_IS_STR(args[0]));
assert(MP_OBJ_IS_STR(args[1]));
assert(MP_OBJ_IS_STR(args[2]));
machine_int_t max_rep = 0;
machine_int_t max_rep = -1;
if (n_args == 4) {
assert(MP_OBJ_IS_SMALL_INT(args[3]));
max_rep = MP_OBJ_SMALL_INT_VALUE(args[3]);
max_rep = mp_obj_get_int(args[3]);
if (max_rep == 0) {
return args[0];
} else if (max_rep < 0) {
max_rep = 0;
max_rep = -1;
}
}
// if max_rep is still 0 by this point we will need to do all possible replacements
// check argument types
if (!MP_OBJ_IS_STR(args[1])) {
bad_implicit_conversion(args[1]);
}
if (!MP_OBJ_IS_STR(args[2])) {
bad_implicit_conversion(args[2]);
}
// extract string data
GET_STR_DATA_LEN(args[0], str, str_len);
GET_STR_DATA_LEN(args[1], old, old_len);
GET_STR_DATA_LEN(args[2], new, new_len);
@ -1143,8 +1152,20 @@ STATIC mp_obj_t str_replace(uint n_args, const mp_obj_t *args) {
machine_uint_t num_replacements_done = 0;
const byte *old_occurrence;
const byte *offset_ptr = str;
machine_uint_t offset_num = 0;
while ((old_occurrence = find_subbytes(offset_ptr, str_len - offset_num, old, old_len, 1)) != NULL) {
machine_uint_t str_len_remain = str_len;
if (old_len == 0) {
// if old_str is empty, copy new_str to start of replaced string
// copy the replacement string
if (data != NULL) {
memcpy(data, new, new_len);
}
replaced_str_index += new_len;
num_replacements_done++;
}
while (num_replacements_done != max_rep && str_len_remain > 0 && (old_occurrence = find_subbytes(offset_ptr, str_len_remain, old, old_len, 1)) != NULL) {
if (old_len == 0) {
old_occurrence += 1;
}
// copy from just after end of last occurrence of to-be-replaced string to right before start of next occurrence
if (data != NULL) {
memcpy(data + replaced_str_index, offset_ptr, old_occurrence - offset_ptr);
@ -1156,19 +1177,15 @@ STATIC mp_obj_t str_replace(uint n_args, const mp_obj_t *args) {
}
replaced_str_index += new_len;
offset_ptr = old_occurrence + old_len;
offset_num = offset_ptr - str;
str_len_remain = str + str_len - offset_ptr;
num_replacements_done++;
if (max_rep != 0 && num_replacements_done == max_rep){
break;
}
}
// copy from just after end of last occurrence of to-be-replaced string to end of old string
if (data != NULL) {
memcpy(data + replaced_str_index, offset_ptr, str_len - offset_num);
memcpy(data + replaced_str_index, offset_ptr, str_len_remain);
}
replaced_str_index += str_len - offset_num;
replaced_str_index += str_len_remain;
if (data == NULL) {
// first pass
@ -1178,6 +1195,7 @@ STATIC mp_obj_t str_replace(uint n_args, const mp_obj_t *args) {
} else {
// substr found, allocate new string
replaced_str = mp_obj_str_builder_start(mp_obj_get_type(args[0]), replaced_str_index, &data);
assert(data != NULL);
}
} else {
// second pass, we are done

5
tests/basics/string_replace.py
View File

@ -6,3 +6,8 @@ print("aabbaabbaabbaa".replace("aa", "cc", 3))
print("a".replace("aa", "bb"))
print("testingtesting".replace("ing", ""))
print("testINGtesting".replace("ing", "ING!"))
print("".replace("", "1"))
print("A".replace("", "1"))
print("AB".replace("", "1"))
print("AB".replace("", "12"))