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225 righe
4.2 KiB
225 righe
4.2 KiB
#pragma once
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#include <type_traits>
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#include "gp_config.hpp"
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#include "gp/exception.hpp"
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#include "gp/algorithm/move.hpp"
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#include "gp/algorithm/modifiers.hpp"
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namespace gp{
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struct nullopt_t{};
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constexpr nullopt_t nullopt;
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template<
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typename T,
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typename allocator = gp_config::memory_module::default_allocator,
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bool copy_allocator = false,
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bool B = std::is_final<T>::value || std::is_fundamental<T>::value
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>
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class optional;
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template<typename T, typename allocator, bool copy_allocator>
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class optional<T, allocator, copy_allocator, true>{
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bool ready = false;
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char buffer[sizeof(T)];
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typename gp::either<
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copy_allocator,
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allocator,
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gp::reference_wrapper<allocator>
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>::type alloc;
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public:
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constexpr optional(allocator p = allocator{})
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: ready{false}
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, alloc(p)
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{}
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constexpr optional(nullopt_t, allocator p = allocator{})
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: ready{false}
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, alloc(p)
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{}
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constexpr optional(T& value, allocator p = allocator{})
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: ready{true}
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, alloc(p)
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{
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new(buffer) T(value);
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}
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constexpr optional(T&& value, allocator p = allocator{})
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: ready{true}
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, alloc(p)
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{
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new(buffer) T(gp::move(value));
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}
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optional& operator=(nullopt_t) {
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if(ready) {
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((T*)buffer)->~T();
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ready = false;
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}
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return *this;
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}
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optional& operator=(T& value) {
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if(ready) {
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*(T*)buffer = value;
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} else {
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ready = true;
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new(buffer) T(value);
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}
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return *this;
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}
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optional& operator=(T&& value) {
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if(ready) {
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*(T*)buffer = gp::move(value);
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} else {
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ready = true;
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new(buffer) T(gp::move(value));
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}
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return *this;
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}
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constexpr bool has_value()
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{
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return ready;
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}
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constexpr T& value()
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{
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if constexpr (gp_config::has_exceptions)
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{
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if(!ready)
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{
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throw bad_optional{};
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}
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} else {
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gp_config::assertion(ready, "bad optional access");
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}
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return *reinterpret_cast<T*>(buffer);
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}
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};
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template<typename T, typename allocator, bool copy_allocator>
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class optional<T, allocator, copy_allocator, false>{
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bool ready = false;
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T* ptr;
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typename gp::either<
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copy_allocator,
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allocator,
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gp::reference_wrapper<allocator>
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>::type alloc;
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public:
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constexpr optional(allocator p = allocator{})
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: ready{false}
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, alloc(p)
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{}
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constexpr optional(nullopt_t, allocator p = allocator{})
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: ready{false}
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, alloc(p)
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{}
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template<typename U>
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constexpr optional(U& value, allocator p = allocator{})
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: ready{true}
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, alloc(p)
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{
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ptr = new U(value); // TODO: Use allocators
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}
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template<typename U>
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constexpr optional(U&& value, allocator p = allocator{})
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: ready{true}
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, alloc(p)
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{
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ptr = new U(gp::move(value)); // TODO: Use allocators
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}
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optional& operator=(nullopt_t) {
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if(ready) {
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delete ptr;
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ready = false;
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}
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return *this;
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}
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template<typename U>
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optional& operator=(U& value) {
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if(ready) {
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if constexpr (std::is_same_v<T, U>) {
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*ptr = value;
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} else {
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delete ptr; // TODO: Use allocators
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ptr = new U(value); // TODO: Use allocators
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}
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} else {
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ready = true;
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ptr = new U(value); // TODO: Use allocators
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}
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return *this;
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}
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optional& operator=(optional&& value){
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if(ready) {
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delete ptr; // TODO: Use allocators
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}
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if(value.ready) {
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ptr = value.ptr;
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value.ready = false;
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ready = true;
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return *this;
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} else {
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ready = false;
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return *this;
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}
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}
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template<typename U>
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optional& operator=(U&& value) {
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if(ready) {
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if constexpr (std::is_same_v<T, U>) {
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*ptr = gp::move(value);
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} else {
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delete ptr; // TODO: Use allocators
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ptr = new U(gp::move(value)); // TODO: Use allocators
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}
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} else {
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ready = true;
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ptr = new U(gp::move(value)); // TODO: Use allocators
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}
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return *this;
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}
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operator T&() {
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gp_config::assertion(ready, "bad optional access");
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return *ptr;
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}
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constexpr bool has_value()
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{
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return ready;
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}
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constexpr T& value()
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{
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if constexpr (gp_config::has_exceptions)
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{
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if(!ready)
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{
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throw bad_optional{};
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}
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} else {
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gp_config::assertion(ready, "bad optional access");
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}
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return *ptr;
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}
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~optional() {
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if(ready) {
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delete ptr; // TODO: Use allocators
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}
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}
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};
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}
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