mirror of https://github.com/bsnes-emu/bsnes.git
108 lines
2.3 KiB
C++
108 lines
2.3 KiB
C++
#ifdef NALL_STRING_INTERNAL_HPP
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/*
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small string optimization (SSO) allocator
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sizeof(string) == 16 (amd64)
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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 < 8)
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cons:
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* added overhead to fetch data()
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* 32-bit platforms limited to (capacity < 4)
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* pass-by-value requires heap allocation
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*/
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namespace nall {
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char* string::data() {
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if(_capacity < SSO) return _text;
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return _data;
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}
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const char* string::data() const {
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if(_capacity < SSO) return _text;
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return _data;
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}
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void string::reserve(unsigned capacity) {
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if(capacity > _capacity) {
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if(capacity >= SSO) {
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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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memcpy(temp, _text, SSO);
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_data = (char*)malloc(capacity + 1);
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memcpy(_data, temp, SSO);
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} else {
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_data = (char*)realloc(_data, capacity + 1);
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}
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}
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_capacity = capacity;
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data()[_capacity] = 0;
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}
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}
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void string::resize(unsigned size) {
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reserve(size);
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data()[_size = size] = 0;
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}
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void string::reset() {
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if(_capacity >= SSO) 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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}
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string& string::operator=(const string& source) {
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if(&source == this) return *this;
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if(source._capacity >= SSO) {
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_data = (char*)malloc(source._capacity + 1);
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_capacity = source._capacity;
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_size = source._size;
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memcpy(_data, source.data(), source.size() + 1);
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} else {
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memcpy(_text, source._text, SSO);
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_capacity = SSO - 1;
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_size = strlen(_text);
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}
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return *this;
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}
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string& string::operator=(string&& source) {
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if(&source == this) return *this;
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memcpy(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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template<typename T, typename... Args> string::string(T&& source, Args&&... args) {
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_data = nullptr;
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_capacity = SSO - 1;
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_size = 0;
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sprint(*this, std::forward<T>(source), std::forward<Args>(args)...);
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}
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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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string::~string() {
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if(_capacity >= SSO) free(_data);
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}
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}
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#endif
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