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added StringBuilder class 

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.
This commit is contained in:
Karroffel 2017-09-01 15:43:23 +02:00
parent 1e0fc4dc4e
commit 95a0886f93
2 changed files with 173 additions and 0 deletions
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94
core/string_builder.cpp Normal file
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/*************************************************************************/
/* string_builder.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "string_builder.h"
#include <string.h>
StringBuilder &StringBuilder::append(const String &p_string) {
strings.push_back(p_string);
appended_strings.push_back(-1);
string_length += p_string.length();
return *this;
}
StringBuilder &StringBuilder::append(const char *p_cstring) {
int32_t len = strlen(p_cstring);
c_strings.push_back(p_cstring);
appended_strings.push_back(len);
string_length += len;
return *this;
}
String StringBuilder::as_string() const {
CharType *buffer = memnew_arr(CharType, string_length);
int current_position = 0;
int godot_string_elem = 0;
int c_string_elem = 0;
for (int i = 0; i < appended_strings.size(); i++) {
if (appended_strings[i] == -1) {
// Godot string
const String &s = strings[godot_string_elem];
memcpy(buffer + current_position, s.ptr(), s.length() * sizeof(CharType));
current_position += s.length();
godot_string_elem++;
} else {
const char *s = c_strings[c_string_elem];
for (int32_t j = 0; j < appended_strings[i]; j++) {
buffer[current_position + j] = s[j];
}
current_position += appended_strings[i];
c_string_elem++;
}
}
String final_string = String(buffer, string_length);
memdelete_arr(buffer);
return final_string;
}

79
core/string_builder.h Normal file
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/*************************************************************************/
/* string_builder.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef STRING_BUILDER_H
#define STRING_BUILDER_H
#include "core/ustring.h"
#include "core/vector.h"
class StringBuilder {
uint32_t string_length = 0;
Vector<String> strings;
Vector<const char *> c_strings;
// -1 means it's a Godot String
// a natural number means C string.
Vector<int32_t> appended_strings;
public:
StringBuilder &append(const String &p_string);
StringBuilder &append(const char *p_cstring);
_FORCE_INLINE_ StringBuilder &operator+(const String &p_string) {
return append(p_string);
}
_FORCE_INLINE_ StringBuilder &operator+(const char *p_cstring) {
return append(p_cstring);
}
_FORCE_INLINE_ void operator+=(const String &p_string) {
append(p_string);
}
_FORCE_INLINE_ void operator+=(const char *p_cstring) {
append(p_cstring);
}
_FORCE_INLINE_ int num_strings_appended() const {
return appended_strings.size();
}
String as_string() const;
_FORCE_INLINE_ operator String() const {
return as_string();
}
};
#endif // STRING_BUILDER_H