thor-os/tstl/include/unique_ptr.hpp

//=======================================================================
// Copyright Baptiste Wicht 2013-2016.
// Distributed under the terms of the MIT License.
// (See accompanying file LICENSE or copy at
//  http://www.opensource.org/licenses/MIT)
//=======================================================================

#ifndef UNIQUE_PTR_H
#define UNIQUE_PTR_H

#include <tuple.hpp>
#include <algorithms.hpp>

namespace std {

template<typename T>
struct default_delete {
    constexpr default_delete() = default;

    constexpr default_delete(const default_delete&) {}

    void operator()(T* ptr) const {
        static_assert(sizeof(T) > 0, "Type must be complete");
        delete ptr;
    }
};

//Partial specialization for arrays
template<typename T>
struct default_delete<T[]> {
    constexpr default_delete() = default;

    constexpr default_delete(const default_delete&) {}

    void operator()(T* ptr) const {
        static_assert(sizeof(T) > 0, "Type must be complete");
        delete[] ptr;
    }
};

template <typename T, typename D = default_delete<T>>
class unique_ptr {
public:
    using pointer_type = T*;
    using element_type = T;
    using deleter_type = D;

private:
    using data_impl = tuple<pointer_type, deleter_type>;

    data_impl _data;

public:
    unique_ptr() : _data() {}
    unique_ptr(decltype(nullptr)) : unique_ptr() {}

    explicit unique_ptr(pointer_type p) : _data(make_tuple(p, deleter_type())) {}

    unique_ptr(unique_ptr&& u) : _data(make_tuple(u.unlock(), u.get_deleter())) {}
    unique_ptr& operator=(unique_ptr&& u){
        reset(u.unlock());
        get_deleter() = std::forward<deleter_type>(u.get_deleter());
        return *this;
    }

    ~unique_ptr(){
        reset();
    }

    // Disable copy
    unique_ptr(const unique_ptr& rhs) = delete;
    unique_ptr& operator=(const unique_ptr& rhs) = delete;

    unique_ptr& operator=(decltype(nullptr)){
        reset();
        return *this;
    }

    //Access

    element_type& operator*() const {
        return *get();
    }

    pointer_type operator->() const {
        return get();
    }

    pointer_type get() const {
        return std::get<0>(_data);
    }

    deleter_type& get_deleter(){
        return std::get<1>(_data);
    }

    const deleter_type& get_deleter() const {
        return std::get<1>(_data);
    }

    explicit operator bool() const {
        return get() == pointer_type() ? false : true;
    }

    pointer_type unlock(){
        pointer_type p = get();
        std::get<0>(_data) = pointer_type();
        return p;
    }

    void reset(pointer_type p = pointer_type()){
        if(get() != pointer_type()){
            get_deleter()(get());
        }

        std::get<0>(_data) = p;
    }
};

//Partial specialization for array
template <typename T, typename D>
class unique_ptr<T[], D> {
public:
    using pointer_type = T*;
    using element_type = T;
    using deleter_type = D;

private:
    using data_impl = tuple<pointer_type, deleter_type>;

    data_impl _data;

public:
    unique_ptr() : _data() {}
    unique_ptr(decltype(nullptr)) : unique_ptr() {}

    explicit unique_ptr(pointer_type p) : _data(make_tuple(p, deleter_type())) {}

    unique_ptr(unique_ptr&& u) : _data(make_tuple(u.unlock(), u.get_deleter())) {}
    unique_ptr& operator=(unique_ptr&& u){
        reset(u.unlock());
        get_deleter() = std::forward<deleter_type>(u.get_deleter());
        return *this;
    }

    ~unique_ptr(){
        reset();
    }

    // Disable copy
    unique_ptr(const unique_ptr& rhs) = delete;
    unique_ptr& operator=(const unique_ptr& rhs) = delete;

    unique_ptr& operator=(decltype(nullptr)){
        reset();
        return *this;
    }

    pointer_type get() const {
        return std::get<0>(_data);
    }

    deleter_type& get_deleter(){
        return std::get<1>(_data);
    }

    const deleter_type& get_deleter() const {
        return std::get<1>(_data);
    }

    element_type& operator[](size_t i) const {
        return get()[i];
    }

    explicit operator bool() const {
        return get() == pointer_type() ? false : true;
    }

    pointer_type unlock(){
        pointer_type p = get();
        std::get<0>(_data) = pointer_type();
        return p;
    }

    void reset(){
        reset(pointer_type());
    }

    void reset(pointer_type p){
        auto tmp = get();
        std::get<0>(_data) = p;
        if(tmp){
            get_deleter()(tmp);
        }
    }
};

static_assert(sizeof(unique_ptr<long>) == sizeof(long), "unique_ptr must have zero overhead with default deleter");
static_assert(sizeof(unique_ptr<long[]>) == sizeof(long), "unique_ptr must have zero overhead with default deleter");

template <typename T, typename... Args>
std::unique_ptr<T> make_unique(Args&&... args){
    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}

} //end of namespace std

#endif