value_ptr.h

// Source: https://github.com/LoopPerfect/valuable
// SPDX-License-Identifier: MIT
//
// This file has been modified by Adobe.
//
// All modifications are Copyright 2022 Adobe.
//
// MIT License
//
// Copyright (c) 2017 LoopPerfect
//
// 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.

#pragma once

#include <memory>

/// @addtogroup group-utils-misc
/// @{

#ifndef LA_DECLSPEC_EMPTY_BASES
#ifdef _MSC_VER
#define LA_DECLSPEC_EMPTY_BASES __declspec(empty_bases)
#else
#define LA_DECLSPEC_EMPTY_BASES
#endif
#endif

namespace lagrange {

/// @cond LA_INTERNAL_DOCS

namespace detail {

struct spacer
{
};

// For details of class_tag use here, see
// https://mortoray.com/2013/06/03/overriding-the-broken-universal-reference-t/
template <typename T>
struct class_tag
{
};

template <class T, class Deleter, class T2>
struct LA_DECLSPEC_EMPTY_BASES compressed_ptr : std::unique_ptr<T, Deleter>, T2
{
    using T1 = std::unique_ptr<T, Deleter>;
    compressed_ptr() = default;
    compressed_ptr(compressed_ptr&&) = default;
    compressed_ptr(const compressed_ptr&) = default;
    compressed_ptr(T2&& a2)
        : T2(std::move(a2))
    {}
    compressed_ptr(const T2& a2)
        : T2(a2)
    {}
    template <typename A1>
    compressed_ptr(A1&& a1)
        : compressed_ptr(
              std::forward<A1>(a1),
              class_tag<typename std::decay<A1>::type>(),
              spacer(),
              spacer())
    {}
    template <typename A1, typename A2>
    compressed_ptr(A1&& a1, A2&& a2)
        : compressed_ptr(
              std::forward<A1>(a1),
              std::forward<A2>(a2),
              class_tag<typename std::decay<A2>::type>(),
              spacer())
    {}
    template <typename A1, typename A2, typename A3>
    compressed_ptr(A1&& a1, A2&& a2, A3&& a3)
        : T1(std::forward<A1>(a1), std::forward<A2>(a2))
        , T2(std::forward<A3>(a3))
    {}

    template <typename A1>
    compressed_ptr(A1&& a1, class_tag<typename std::decay<A1>::type>, spacer, spacer)
        : T1(std::forward<A1>(a1))
    {}
    template <typename A1, typename A2>
    compressed_ptr(A1&& a1, A2&& a2, class_tag<Deleter>, spacer)
        : T1(std::forward<A1>(a1), std::forward<A2>(a2))
    {}
    template <typename A1, typename A2>
    compressed_ptr(A1&& a1, A2&& a2, class_tag<T2>, spacer)
        : T1(std::forward<A1>(a1))
        , T2(std::forward<A2>(a2))
    {}
};

} // namespace detail

template <typename T>
struct default_clone
{
    default_clone() = default;
    T* operator()(T const& x) const { return new T(x); }
    T* operator()(T&& x) const { return new T(std::move(x)); }
};

/// @endcond

///
/// Smart pointer with value semantics. Copy/moving the pointer will copy/move the underlying
/// object. This is useful to implement PIMPL idioms.
///
/// @tparam     T        Object type of the pointee.
/// @tparam     Cloner   Optional cloner functor.
/// @tparam     Deleter  Optional deleter functor.
///
template <class T, class Cloner = default_clone<T>, class Deleter = std::default_delete<T>>
class value_ptr
{
    ::lagrange::detail::compressed_ptr<T, Deleter, Cloner> ptr_;

    std::unique_ptr<T, Deleter>& ptr() { return ptr_; }
    std::unique_ptr<T, Deleter> const& ptr() const { return ptr_; }

    T* clone(T const& x) const { return get_cloner()(x); }

public:
    using pointer = T*;
    using element_type = T;
    using cloner_type = Cloner;
    using deleter_type = Deleter;

    value_ptr() = default;

    value_ptr(const T& value)
        : ptr_(cloner_type()(value))
    {}
    value_ptr(T&& value)
        : ptr_(cloner_type()(std::move(value)))
    {}

    value_ptr(const Cloner& value)
        : ptr_(value)
    {}
    value_ptr(Cloner&& value)
        : ptr_(value)
    {}

    template <typename V, typename ClonerOrDeleter>
    value_ptr(V&& value, ClonerOrDeleter&& a2)
        : ptr_(std::forward<V>(value), std::forward<ClonerOrDeleter>(a2))
    {}

    template <typename V, typename C, typename D>
    value_ptr(V&& value, C&& cloner, D&& deleter)
        : ptr_(std::forward<V>(value), std::forward<D>(deleter), std::forward<C>(cloner))
    {}

    value_ptr(value_ptr const& v)
        : ptr_{nullptr, v.get_cloner()}
    {
        if (v) {
            ptr().reset(clone(*v));
        }
    }
    value_ptr(value_ptr&& v) = default;

    explicit value_ptr(pointer value)
        : ptr_(value)
    {}
    pointer release() { return ptr().release(); }

    T* get() noexcept { return ptr().get(); }
    T const* get() const noexcept { return ptr().get(); }

    Cloner& get_cloner() noexcept { return ptr_; }
    Cloner const& get_cloner() const noexcept { return ptr_; }

    Deleter& get_deleter() noexcept { return ptr_; }
    Deleter const& get_deleter() const noexcept { return ptr_; }

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

    T const* operator->() const noexcept { return get(); }
    T* operator->() noexcept { return get(); }

    value_ptr<T>& operator=(value_ptr&& v) noexcept
    {
        ptr() = std::move(v.ptr());
        get_cloner() = std::move(v.get_cloner());
        return *this;
    }

    value_ptr<T>& operator=(value_ptr const& v)
    {
        ptr().reset(v.get_cloner()(*v));
        get_cloner() = v.get_cloner();
        return *this;
    }

    operator bool() const noexcept { return !!ptr(); }
    ~value_ptr() = default;
};

///
/// Helper function to create a value_ptr for a given type.
///
/// @param      args  Arguments to forward to the object's constructor.
///
/// @tparam     T     Type of the object to create.
/// @tparam     Args  Argument types for the object's constructor.
///
/// @return     A value_ptr of the desired type.
///
template <class T, class... Args>
value_ptr<T> make_value_ptr(Args&&... args)
{
    return value_ptr<T>(new T(std::forward<Args>(args)...));
}

/// @}

} // namespace lagrange