mirror of https://github.com/bsnes-emu/bsnes.git
94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
#pragma once
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/*
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small string optimization (SSO) allocator
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sizeof(string) == 8 + string::SSO
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utilizes a union to store small strings directly into text pointer
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bypasses the need to allocate heap memory for small strings
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requires extra computations, which can be slower for large strings
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pros:
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* potential for in-place resize
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* no heap allocation when (capacity < SSO)
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cons:
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* added overhead to fetch data()
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* pass-by-value requires heap allocation when (capacity >= SSO)
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*/
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namespace nall {
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string::string() {
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_data = nullptr;
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_capacity = SSO - 1;
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_size = 0;
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}
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auto string::get() -> char* {
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if(_capacity < SSO) return _text;
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return _data;
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}
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auto string::data() const -> const char* {
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if(_capacity < SSO) return _text;
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return _data;
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}
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auto string::reset() -> type& {
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if(_capacity >= SSO) memory::free(_data);
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_data = nullptr;
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_capacity = SSO - 1;
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_size = 0;
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return *this;
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}
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auto string::reserve(uint capacity) -> type& {
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if(capacity <= _capacity) return *this;
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capacity = bit::round(capacity + 1) - 1;
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if(_capacity < SSO) {
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char _temp[SSO];
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memory::copy(_temp, _text, SSO);
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_data = (char*)memory::allocate(_capacity = capacity + 1);
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memory::copy(_data, _temp, SSO);
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} else {
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_data = (char*)memory::resize(_data, _capacity = capacity + 1);
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}
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return *this;
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}
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auto string::resize(uint size) -> type& {
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reserve(size);
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get()[_size = size] = 0;
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return *this;
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}
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auto string::operator=(const string& source) -> type& {
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if(&source == this) return *this;
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reset();
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if(source._capacity >= SSO) {
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_data = (char*)memory::allocate(source._capacity + 1);
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_capacity = source._capacity;
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_size = source._size;
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memory::copy(_data, source._data, source._size + 1);
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} else {
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memory::copy(_text, source._text, SSO);
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_capacity = SSO - 1;
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_size = source._size;
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}
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return *this;
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}
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auto string::operator=(string&& source) -> type& {
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if(&source == this) return *this;
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reset();
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memory::copy(this, &source, sizeof(string));
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source._data = nullptr;
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source._capacity = SSO - 1;
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source._size = 0;
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return *this;
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}
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}
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