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[Core] Optimize String::replace methods
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Performs a single allocation, only when any instances are found, and
avoids concatenations and other unnecessary conversions.

(cherry picked from commit cbaec62)
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@AThousandShips @Spartan322
AThousandShips authored and Spartan322 committed Nov 16, 2024
1 parent 2060bec commit 285ada4
Showing 1 changed file with 157 additions and 60 deletions.
217 changes: 157 additions & 60 deletions core/string/ustring.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3994,54 +3994,161 @@ String String::format(const Variant &values, const String &placeholder) const {
return new_string;
}

String String::replace(const String &p_key, const String &p_with) const {
String new_string;
static String _replace_common(const String &p_this, const String &p_key, const String &p_with, bool p_case_insensitive) {
if (p_key.is_empty() || p_this.is_empty()) {
return p_this;
}

const int key_length = p_key.length();

int search_from = 0;
int result = 0;

while ((result = find(p_key, search_from)) >= 0) {
new_string += substr(search_from, result - search_from);
new_string += p_with;
search_from = result + p_key.length();
LocalVector<int> found;

while ((result = (p_case_insensitive ? p_this.findn(p_key, search_from) : p_this.find(p_key, search_from))) >= 0) {
found.push_back(result);
search_from = result + key_length;
}

if (search_from == 0) {
return *this;
if (found.is_empty()) {
return p_this;
}

new_string += substr(search_from, length() - search_from);
String new_string;

const int with_length = p_with.length();
const int old_length = p_this.length();

new_string.resize(old_length + found.size() * (with_length - key_length) + 1);

char32_t *new_ptrw = new_string.ptrw();
const char32_t *old_ptr = p_this.ptr();
const char32_t *with_ptr = p_with.ptr();

int last_pos = 0;

for (const int &pos : found) {
if (last_pos != pos) {
memcpy(new_ptrw, old_ptr + last_pos, (pos - last_pos) * sizeof(char32_t));
new_ptrw += (pos - last_pos);
}
if (with_length) {
memcpy(new_ptrw, with_ptr, with_length * sizeof(char32_t));
new_ptrw += with_length;
}
last_pos = pos + key_length;
}

if (last_pos != old_length) {
memcpy(new_ptrw, old_ptr + last_pos, (old_length - last_pos) * sizeof(char32_t));
new_ptrw += old_length - last_pos;
}

*new_ptrw = 0;

return new_string;
}

String String::replace(const char *p_key, const char *p_with) const {
String new_string;
static String _replace_common(const String &p_this, char const *p_key, char const *p_with, bool p_case_insensitive) {
int key_length = strlen(p_key);

if (key_length == 0 || p_this.is_empty()) {
return p_this;
}

int search_from = 0;
int result = 0;

while ((result = find(p_key, search_from)) >= 0) {
new_string += substr(search_from, result - search_from);
new_string += p_with;
int k = 0;
while (p_key[k] != '\0') {
k++;
LocalVector<int> found;

while ((result = (p_case_insensitive ? p_this.findn(p_key, search_from) : p_this.find(p_key, search_from))) >= 0) {
found.push_back(result);
search_from = result + key_length;
}

if (found.is_empty()) {
return p_this;
}

String new_string;

// Create string to speed up copying as we can't do `memcopy` between `char32_t` and `char`.
const String with_string(p_with);
const int with_length = with_string.length();
const int old_length = p_this.length();

new_string.resize(old_length + found.size() * (with_length - key_length) + 1);

char32_t *new_ptrw = new_string.ptrw();
const char32_t *old_ptr = p_this.ptr();
const char32_t *with_ptr = with_string.ptr();

int last_pos = 0;

for (const int &pos : found) {
if (last_pos != pos) {
memcpy(new_ptrw, old_ptr + last_pos, (pos - last_pos) * sizeof(char32_t));
new_ptrw += (pos - last_pos);
}
search_from = result + k;
if (with_length) {
memcpy(new_ptrw, with_ptr, with_length * sizeof(char32_t));
new_ptrw += with_length;
}
last_pos = pos + key_length;
}

if (search_from == 0) {
return *this;
if (last_pos != old_length) {
memcpy(new_ptrw, old_ptr + last_pos, (old_length - last_pos) * sizeof(char32_t));
new_ptrw += old_length - last_pos;
}

new_string += substr(search_from, length() - search_from);
*new_ptrw = 0;

return new_string;
}

String String::replace(const String &p_key, const String &p_with) const {
return _replace_common(*this, p_key, p_with, false);
}

String String::replace(const char *p_key, const char *p_with) const {
return _replace_common(*this, p_key, p_with, false);
}

String String::replace_first(const String &p_key, const String &p_with) const {
int pos = find(p_key);
if (pos >= 0) {
return substr(0, pos) + p_with + substr(pos + p_key.length(), length());
const int old_length = length();
const int key_length = p_key.length();
const int with_length = p_with.length();

String new_string;
new_string.resize(old_length + (with_length - key_length) + 1);

char32_t *new_ptrw = new_string.ptrw();
const char32_t *old_ptr = ptr();
const char32_t *with_ptr = p_with.ptr();

if (pos > 0) {
memcpy(new_ptrw, old_ptr, pos * sizeof(char32_t));
new_ptrw += pos;
}

if (with_length) {
memcpy(new_ptrw, with_ptr, with_length * sizeof(char32_t));
new_ptrw += with_length;
}
pos += key_length;

if (pos != old_length) {
memcpy(new_ptrw, old_ptr + pos, (old_length - pos) * sizeof(char32_t));
new_ptrw += (old_length - pos);
}

*new_ptrw = 0;

return new_string;
}

return *this;
Expand All @@ -4050,55 +4157,45 @@ String String::replace_first(const String &p_key, const String &p_with) const {
String String::replace_first(const char *p_key, const char *p_with) const {
int pos = find(p_key);
if (pos >= 0) {
int substring_length = strlen(p_key);
return substr(0, pos) + p_with + substr(pos + substring_length, length());
}
const int old_length = length();
const int key_length = strlen(p_key);
const int with_length = strlen(p_with);

return *this;
}

String String::replacen(const String &p_key, const String &p_with) const {
String new_string;
int search_from = 0;
int result = 0;
String new_string;
new_string.resize(old_length + (with_length - key_length) + 1);

while ((result = findn(p_key, search_from)) >= 0) {
new_string += substr(search_from, result - search_from);
new_string += p_with;
search_from = result + p_key.length();
}
char32_t *new_ptrw = new_string.ptrw();
const char32_t *old_ptr = ptr();

if (search_from == 0) {
return *this;
}
if (pos > 0) {
memcpy(new_ptrw, old_ptr, pos * sizeof(char32_t));
new_ptrw += pos;
}

new_string += substr(search_from, length() - search_from);
return new_string;
}
for (int i = 0; i < with_length; ++i) {
*new_ptrw++ = p_with[i];
}
pos += key_length;

String String::replacen(const char *p_key, const char *p_with) const {
String new_string;
int search_from = 0;
int result = 0;
int substring_length = strlen(p_key);
if (pos != old_length) {
memcpy(new_ptrw, old_ptr + pos, (old_length - pos) * sizeof(char32_t));
new_ptrw += (old_length - pos);
}

if (substring_length == 0) {
return *this; // there's nothing to match or substitute
}
*new_ptrw = 0;

while ((result = findn(p_key, search_from)) >= 0) {
new_string += substr(search_from, result - search_from);
new_string += p_with;
search_from = result + substring_length;
return new_string;
}

if (search_from == 0) {
return *this;
}
return *this;
}

new_string += substr(search_from, length() - search_from);
String String::replacen(const String &p_key, const String &p_with) const {
return _replace_common(*this, p_key, p_with, true);
}

return new_string;
String String::replacen(const char *p_key, const char *p_with) const {
return _replace_common(*this, p_key, p_with, true);
}

String String::repeat(int p_count) const {
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