Merge pull request godotengine#101493 from Ivorforce/string-equal-fast

Optimize `String` `==`, `ends_with` and `begins_with` by using `memcmp`.

Author: akien-mga

core/string/ustring.cpp

@@ -550,18 +550,7 @@ bool String::operator==(const char32_t *p_str) const {
 		return true;
 	}
 
-	int l = length();
-
-	const char32_t *dst = get_data();
-
-	/* Compare char by char */
-	for (int i = 0; i < l; i++) {
-		if (p_str[i] != dst[i]) {
-			return false;
-		}
-	}
-
-	return true;
+	return memcmp(ptr(), p_str, len * sizeof(char32_t)) == 0;
 }
 
 bool String::operator==(const String &p_str) const {
@@ -572,23 +561,11 @@ bool String::operator==(const String &p_str) const {
 		return true;
 	}
 
-	int l = length();
-
-	const char32_t *src = get_data();
-	const char32_t *dst = p_str.get_data();
-
-	/* Compare char by char */
-	for (int i = 0; i < l; i++) {
-		if (src[i] != dst[i]) {
-			return false;
-		}
-	}
-
-	return true;
+	return memcmp(ptr(), p_str.ptr(), length() * sizeof(char32_t)) == 0;
 }
 
 bool String::operator==(const StrRange<char32_t> &p_str_range) const {
-	int len = p_str_range.len;
+	const int len = p_str_range.len;
 
 	if (length() != len) {
 		return false;
@@ -597,17 +574,7 @@ bool String::operator==(const StrRange<char32_t> &p_str_range) const {
 		return true;
 	}
 
-	const char32_t *c_str = p_str_range.c_str;
-	const char32_t *dst = &operator[](0);
-
-	/* Compare char by char */
-	for (int i = 0; i < len; i++) {
-		if (c_str[i] != dst[i]) {
-			return false;
-		}
-	}
-
-	return true;
+	return memcmp(ptr(), p_str_range.c_str, len * sizeof(char32_t)) == 0;
 }
 
 bool operator==(const char *p_chr, const String &p_str) {
@@ -3573,25 +3540,15 @@ int String::rfindn(const char *p_str, int p_from) const {
 }
 
 bool String::ends_with(const String &p_string) const {
-	int l = p_string.length();
+	const int l = p_string.length();
 	if (l > length()) {
 		return false;
 	}
-
 	if (l == 0) {
 		return true;
 	}
 
-	const char32_t *p = &p_string[0];
-	const char32_t *s = &operator[](length() - l);
-
-	for (int i = 0; i < l; i++) {
-		if (p[i] != s[i]) {
-			return false;
-		}
-	}
-
-	return true;
+	return memcmp(ptr() + (length() - l), p_string.ptr(), l * sizeof(char32_t)) == 0;
 }
 
 bool String::ends_with(const char *p_string) const {
@@ -3620,25 +3577,15 @@ bool String::ends_with(const char *p_string) const {
 }
 
 bool String::begins_with(const String &p_string) const {
-	int l = p_string.length();
+	const int l = p_string.length();
 	if (l > length()) {
 		return false;
 	}
-
 	if (l == 0) {
 		return true;
 	}
 
-	const char32_t *p = &p_string[0];
-	const char32_t *s = &operator[](0);
-
-	for (int i = 0; i < l; i++) {
-		if (p[i] != s[i]) {
-			return false;
-		}
-	}
-
-	return true;
+	return memcmp(ptr(), p_string.ptr(), l * sizeof(char32_t)) == 0;
 }
 
 bool String::begins_with(const char *p_string) const {