memory.hpp

Go to the documentation of this file.

/*
    Copyright 2013 Adobe
    Distributed under the Boost Software License, Version 1.0.
    (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
*/
/**************************************************************************************************/
 
#ifndef ADOBE_MEMORY_HPP
#define ADOBE_MEMORY_HPP
 
#include <adobe/config.hpp>
 
#include <cassert>
#include <utility>
 
#include <adobe/conversion.hpp>
#include <adobe/functional.hpp>
#include <adobe/memory_fwd.hpp>
 
/**************************************************************************************************/
 
namespace adobe {
 
/**************************************************************************************************/

 
template <typename T>
struct empty_ptr;
 
template <typename T>
struct empty_ptr<T*> {
    bool operator()(const T* x) const throw() { return x == NULL; }
};
 
 
template <typename T>
struct empty_ptr<T (*)[]> {
    bool operator()(const T* x) const throw() { return x == NULL; }
};
 
/*
    REVISIT (sparent) : This is a hack - the new delete_ptr is not a template
    auto_resource is too complicated with the traits classes -
    provide a delete op as a tempalte argument?
*/
 
template <typename T>
struct delete_ptr_trait;
 
template <typename T>
struct delete_ptr_trait<T*> {
    void operator()(const T* x) const { delete x; }
};
 
template <typename T>
struct delete_ptr_trait<T (*)[]> {
    void operator()(const T* x) const { delete[] x; }
};

 
/**************************************************************************************************/
 
template <typename X, class Traits>
class auto_resource;
 
template <typename ptrT>
struct ptr_traits;

template <typename T>
struct ptr_traits<T (*)[]> {
    typedef T element_type;
    typedef T* pointer_type;
    typedef const T* const_pointer_type;
 
    template <class U>
    struct rebind {
        typedef adobe::ptr_traits<U> other;
    };
    enum { is_array = true };
 
    static void delete_ptr(pointer_type x) throw() { delete_ptr_trait<T(*)[]>()(x); }
    static bool empty_ptr(const_pointer_type x) throw() { return adobe::empty_ptr<T(*)[]>()(x); }
};


template <typename T>
struct ptr_traits<T*> {
    typedef T element_type;
    typedef T* pointer_type;
    typedef const pointer_type const_pointer_type;
 
    template <class U>
    struct rebind {
        typedef adobe::ptr_traits<U> other;
    };
    enum { is_array = false };
 
    static void delete_ptr(pointer_type x) throw() { adobe::delete_ptr_trait<T*>()(x); }
    static bool empty_ptr(const_pointer_type x) throw() { return adobe::empty_ptr<T*>()(x); }
};
 
/**************************************************************************************************/
 
#ifndef NO_DOCUMENTATION
 
/*
    REVISIT (sparent) : This could use boost::static_assert but it doesn't seem worth adding a
    boost dependency just for this case.
*/
 
namespace implementation {
template <bool x>
struct adobe_static_assert;
template <>
struct adobe_static_assert<true> {};
} // namespace implementation
 
#endif
 
/**************************************************************************************************/
 
/* REVISIT (sparent) : auto_resource should become unique_resource. */

 
template <typename X, class Traits = ptr_traits<X>>
class auto_resource {
    struct clear_type {};
    operator int() const;
 
public:
    typedef Traits traits_type;
    typedef typename traits_type::element_type element_type;
    typedef typename traits_type::pointer_type pointer_type;
 
    // 20.4.5.1 construct/copy/destroy:
    explicit auto_resource(pointer_type p = 0) throw();
 
    auto_resource(auto_resource&) throw();
    template <typename Y>
    auto_resource(const auto_resource<Y, typename traits_type::template rebind<Y>::other>&) throw();
 
    auto_resource& operator=(auto_resource&) throw();
    template <typename Y>
    auto_resource&
    operator=(auto_resource<Y, typename traits_type::template rebind<Y>::other>) throw();
 
    ~auto_resource() throw();
 
    // assignment from NULL
    auto_resource& operator=(const clear_type*) throw();
 
    // 20.4.5.2 members:
    pointer_type get() const throw();
    pointer_type release() throw();
    void reset(pointer_type p = 0) throw();
 
    // Safe bool conversion (private int conversion prevents unsafe use)
    operator bool() const throw() { return (pointer_m != NULL); }
    bool operator!() const throw();
 
private:
/*
    20.4.5.3 conversions:
 
    NOTE (sparent) : As per the recommendations on standard issue 463 the conversion
    operators through auto_ptr_ref have been removed in favor of using this conditional
    enabled trick.
 
    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#463
*/
// REVISIT: VC 2003 internal compiler error workaround. Some misues of auto_resource will go
// undetected under MSVC until fixed.
// REVISIT: Failes with incomplete types with Apple's LLVM 3.0 compiler.
#if 0
#ifndef BOOST_MSVC
  template <typename Y> struct error_on_const_auto_type;
    template <typename Y> struct error_on_const_auto_type<auto_resource<Y, typename traits_type::template rebind<Y>::other> const>
    { typedef typename auto_resource<Y, typename traits_type::template rebind<Y>::other>::const_auto_type_is_not_allowed type; };
 
    template <class Y>
    auto_resource(Y& rhs, typename error_on_const_auto_type<Y>::type = 0);
#endif
#endif
    pointer_type pointer_m;
};
 
/**************************************************************************************************/
 
template <typename X, class Traits>
inline auto_resource<X, Traits>::auto_resource(pointer_type p) throw() : pointer_m(p) {}
 
template <typename X, class Traits>
inline auto_resource<X, Traits>::auto_resource(auto_resource& x) throw() : pointer_m(x.release()) {}
 
template <typename X, class Traits>
template <typename Y>
inline auto_resource<X, Traits>::auto_resource(
    auto_resource<Y, typename traits_type::template rebind<Y>::other> const& x) throw()
    : pointer_m(const_cast<auto_resource<Y, typename traits_type::template rebind<Y>::other>&>(x)
                    .release()) {}
 
template <typename X, class Traits>
inline auto_resource<X, Traits>& auto_resource<X, Traits>::operator=(auto_resource& x) throw() {
    reset(x.release());
    return *this;
}
 
template <typename X, class Traits>
template <typename Y>
inline auto_resource<X, Traits>& auto_resource<X, Traits>::operator=(
    auto_resource<Y, typename traits_type::template rebind<Y>::other> x) throw() {
    reset(x.release());
    return *this;
}
 
template <typename X, class Traits>
inline auto_resource<X, Traits>::~auto_resource() throw() {
    traits_type::delete_ptr(pointer_m);
}
 
/**************************************************************************************************/
 
template <typename X, class Traits>
inline auto_resource<X, Traits>& auto_resource<X, Traits>::operator=(const clear_type*) throw() {
    reset();
    return *this;
}
 
/**************************************************************************************************/
 
template <typename X, class Traits>
inline typename auto_resource<X, Traits>::pointer_type auto_resource<X, Traits>::get() const
    throw() {
    return pointer_m;
}
 
template <typename X, class Traits>
inline typename auto_resource<X, Traits>::pointer_type auto_resource<X, Traits>::release() throw() {
    pointer_type result(pointer_m);
    pointer_m = NULL;
    return result;
}
 
template <typename X, class Traits>
inline void auto_resource<X, Traits>::reset(pointer_type p) throw() {
    if (pointer_m != p) {
        traits_type::delete_ptr(pointer_m);
        pointer_m = p;
    }
}
 
/**************************************************************************************************/
 
template <typename X, class Traits>
inline bool auto_resource<X, Traits>::operator!() const throw() {
    return !pointer_m;
}
 
/**************************************************************************************************/
 
template <typename T> // T models Regular
inline void destroy(T* p) {
    p->~T();
}
 
/*
    https://en.cppreference.com/w/cpp/memory/construct_at
*/
 
template <class T, class... Args>
T* construct_at(T* p, Args&&... args) {
    return ::new (static_cast<void*>(p)) T(std::forward<Args>(args)...);
}
 
template <typename T, typename U> // T models Regular
[[deprecated("Use adobe::construct_at(p, x)")]] constexpr auto construct(T* p, U&& x) {
    return construct_at(p, std::forward<U>(x));
}
 
template <typename T> // T models Regular
[[deprecated("Use adobe::construct_at(p)")]] constexpr auto construct(T* p) {
    return construct_at(p);
}
 
template <typename F> // F models ForwardIterator
inline void destroy(F f, F l) {
    while (f != l) {
        destroy(&*f);
        ++f;
    }
}
 
/**************************************************************************************************/

template <typename I, // I models InputIterator
          typename F>
// F models ForwardIterator
F uninitialized_move(I f, I l, F r) {
    while (f != l) {
        adobe::construct(&*r, std::move(*f));
        ++f;
        ++r;
    }
    return r;
}
 
/**************************************************************************************************/
 
inline namespace version_1 {

 
struct new_delete_t {
    void* (*new_)(std::size_t);
    void (*delete_)(void*);
};
 
extern const new_delete_t local_new_delete_g;
 
template <>
class capture_allocator<void> {
public:
    void* pointer;
    typedef const void* const_pointer;
    typedef void value_type;
    template <class U>
    struct rebind {
        using other = capture_allocator<U>;
    };
 
    friend inline bool operator==(const capture_allocator&, const capture_allocator&) {
        return true;
    }
 
    friend inline bool operator!=(const capture_allocator&, const capture_allocator&) {
        return false;
    }
};
 
template <typename T>
class capture_allocator {
public:
    typedef std::size_t size_type;
    typedef std::ptrdiff_t difference_type;
    typedef T* pointer;
    typedef const T* const_pointer;
    typedef T& reference;
    typedef const T& const_reference;
    typedef T value_type;
    template <typename U>
    struct rebind {
        typedef capture_allocator<U> other;
    };
 
    capture_allocator() : new_delete_m(&local_new_delete_g) {}
    template <typename U>
    capture_allocator(const capture_allocator<U>& x) : new_delete_m(x.new_delete()) {}
 
    capture_allocator(const capture_allocator&) = default;
    capture_allocator& operator=(const capture_allocator&) = default;
    capture_allocator(capture_allocator&&) noexcept = default;
    capture_allocator& operator=(capture_allocator&&) noexcept = default;
 
    pointer address(reference x) const { return &x; }
    const_pointer address(const_reference x) const { return &x; }
    pointer allocate(size_type n, capture_allocator<void>::const_pointer = 0) {
        if (n > max_size())
            throw std::bad_alloc();
        pointer result = static_cast<pointer>(new_delete_m->new_(n * sizeof(T)));
        if (!result)
            throw std::bad_alloc();
        return result;
    }
    void deallocate(pointer p, size_type) { new_delete_m->delete_(p); }
    size_type max_size() const { return size_type(-1) / sizeof(T); }
    void construct(pointer p, const T& x) { adobe::construct(p, x); }
    void destroy(pointer p) { adobe::destroy(p); }
 
    friend inline bool operator==(const capture_allocator& x, const capture_allocator& y) {
        return x.new_delete_m == y.new_delete_m;
    }
 
    friend inline bool operator!=(const capture_allocator& x, const capture_allocator& y) {
        return x.new_delete_m != y.new_delete_m;
    }
 
    const new_delete_t* new_delete() const { return new_delete_m; }
 
private:
    const new_delete_t* new_delete_m;
};

/**************************************************************************************************/
 
} // namespace version_1
 
/**************************************************************************************************/
 
/*
    Note (sparent) : The aligned storage class is intended to pad out an item of size_t such that
    anything following it is aligned to the max alignement on the machine - in this case, quadword.
 
    REVISIT (sparent) : This is a different beast than C++11 aligned storage. See if we can
    replace usage with C++11 aligned storage.
*/

template <typename T>
struct aligned_storage {
public:
    aligned_storage() { construct_at(&get()); }
 
    explicit aligned_storage(T x) { construct_at(&get(), std::move(x)); }
 
    ~aligned_storage() { destroy(&get()); }
 
    aligned_storage(const aligned_storage& x) { construct_at(&get(), x.get()); }
    aligned_storage(aligned_storage&& x) { construct_at(&get(), std::move(x.get())); }
 
    aligned_storage& operator=(aligned_storage x) {
        swap(*this, x);
        return *this;
    }
 
    T& get() { return *static_cast<T*>(storage()); }
    const T& get() const { return *static_cast<const T*>(storage()); }
 
    friend inline void swap(aligned_storage& x, aligned_storage& y) { swap(x.get(), y.get()); }
 
private:
    enum { word_size = 16 }; // quad word alignment
 
    typedef double
        storage_t[((sizeof(T) + (word_size - 1)) / word_size) * (word_size / sizeof(double))];
 
    void* storage() { return &data_m; }
    const void* storage() const { return &data_m; }
    storage_t data_m;
 
    static_assert(sizeof(T) <= sizeof(storage_t));
};

/**************************************************************************************************/
 
} // namespace adobe
 
/**************************************************************************************************/
 
#endif
 
/**************************************************************************************************/