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Implement str.replace and add tests for it.

This commit is contained in:
xbe 2014-01-30 22:17:30 -08:00
parent 65365778fd
commit 480c15afb5
2 changed files with 73 additions and 0 deletions
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65
py/objstr.c
View File

@ -408,12 +408,76 @@ mp_obj_t str_format(uint n_args, const mp_obj_t *args) {
return s;
}
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]));
int max_rep = 0;
if (n_args == 4) {
assert(MP_OBJ_IS_SMALL_INT(args[3]));
max_rep = MP_OBJ_SMALL_INT_VALUE(args[3]);
if (max_rep == 0) {
return(args[0]);
}
else if (max_rep < 0) {
max_rep = 0;
}
}
//if max_rep is still 0 by this point we will need to do all possible replacements
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);
if (old_len > str_len) {
return(args[0]);
}
size_t required_len = 0;
const byte *old_occurrence;
const byte *offset_ptr = str;
size_t offset_num = 0;
while((old_occurrence = find_subbytes(offset_ptr, str_len - offset_num, old, old_len)) != NULL){
required_len += old_occurrence - offset_ptr;
required_len += new_len;
offset_ptr = old_occurrence + old_len;
offset_num = offset_ptr - str;
}
required_len += str_len - offset_num;
byte *data;
mp_obj_t replaced_str = mp_obj_str_builder_start(mp_obj_get_type(args[0]), required_len, &data);
size_t replaced_str_index = 0;
int replacements_done = 0;
offset_ptr = str;
offset_num = 0;
while((old_occurrence = find_subbytes(offset_ptr, str_len - offset_num, old, old_len)) != NULL){
//copy from just after end of last occurrence of to-be-replaced string to right before start of next occurrence
memcpy(data + replaced_str_index, offset_ptr, old_occurrence - offset_ptr);
replaced_str_index += old_occurrence - offset_ptr;
//copy the replacement string
memcpy(data + replaced_str_index, new, new_len);
replaced_str_index += new_len;
offset_ptr = old_occurrence + old_len;
offset_num = offset_ptr - str;
replacements_done++;
if (max_rep != 0 && replacements_done == max_rep){
break;
}
}
//copy from just after end of last occurrence of to-be-replaced string to end of old string
memcpy(data + replaced_str_index, offset_ptr, str_len - offset_num);
return mp_obj_str_builder_end(replaced_str);
}
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(str_find_obj, 2, 4, str_find);
static MP_DEFINE_CONST_FUN_OBJ_2(str_join_obj, str_join);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(str_split_obj, 1, 3, str_split);
static MP_DEFINE_CONST_FUN_OBJ_2(str_startswith_obj, str_startswith);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(str_strip_obj, 1, 2, str_strip);
static MP_DEFINE_CONST_FUN_OBJ_VAR(str_format_obj, 1, str_format);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(str_replace_obj, 3, 4, str_replace);
static const mp_method_t str_type_methods[] = {
{ "find", &str_find_obj },
@ -422,6 +486,7 @@ static const mp_method_t str_type_methods[] = {
{ "startswith", &str_startswith_obj },
{ "strip", &str_strip_obj },
{ "format", &str_format_obj },
{ "replace", &str_replace_obj },
{ NULL, NULL }, // end-of-list sentinel
};

8
tests/basics/string_replace.py Normal file
View File

@ -0,0 +1,8 @@
print("".replace("a", "b"))
print("aaa".replace("a", "b", 0))
print("aaa".replace("a", "b", -5))
print("asdfasdf".replace("a", "b"))
print("aabbaabbaabbaa".replace("aa", "cc", 3))
print("a".replace("aa", "bb"))
print("testingtesting".replace("ing", ""))
print("testINGtesting".replace("ing", "ING!"))