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When doing large string concatenations the default push_back on the String class can slow down things quite a bit. This is because it has to constantly reallocate the memory and copy the contents. This StringBuilder class delays the concatenation until the size of the resulting string is known.
95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
/*************************************************************************/
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/* string_builder.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#include "string_builder.h"
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#include <string.h>
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StringBuilder &StringBuilder::append(const String &p_string) {
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strings.push_back(p_string);
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appended_strings.push_back(-1);
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string_length += p_string.length();
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return *this;
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}
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StringBuilder &StringBuilder::append(const char *p_cstring) {
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int32_t len = strlen(p_cstring);
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c_strings.push_back(p_cstring);
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appended_strings.push_back(len);
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string_length += len;
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return *this;
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}
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String StringBuilder::as_string() const {
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CharType *buffer = memnew_arr(CharType, string_length);
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int current_position = 0;
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int godot_string_elem = 0;
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int c_string_elem = 0;
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for (int i = 0; i < appended_strings.size(); i++) {
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if (appended_strings[i] == -1) {
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// Godot string
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const String &s = strings[godot_string_elem];
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memcpy(buffer + current_position, s.ptr(), s.length() * sizeof(CharType));
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current_position += s.length();
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godot_string_elem++;
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} else {
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const char *s = c_strings[c_string_elem];
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for (int32_t j = 0; j < appended_strings[i]; j++) {
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buffer[current_position + j] = s[j];
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}
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current_position += appended_strings[i];
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c_string_elem++;
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}
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}
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String final_string = String(buffer, string_length);
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memdelete_arr(buffer);
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return final_string;
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}
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