Corrade/Containers/Array.h

#ifndef Corrade_Containers_Array_h
#define Corrade_Containers_Array_h
/*
    This file is part of Corrade.

    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
                2017, 2018, 2019, 2020 Vladimír Vondruš <mosra@centrum.cz>

    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.
*/

/** @file
 * @brief Class @ref Corrade::Containers::Array
 */

#include <initializer_list>
#include <new>
#include <type_traits>
#include <utility>

#include "Corrade/configure.h"
#include "Corrade/Containers/ArrayView.h"
#include "Corrade/Containers/Tags.h"
#include "Corrade/Containers/constructHelpers.h"

namespace Corrade { namespace Containers {

namespace Implementation {
    template<class T> struct DefaultDeleter {
        T operator()() const { return T{}; }
    };
    template<class T> struct DefaultDeleter<void(*)(T*, std::size_t)> {
        void(*operator()() const)(T*, std::size_t) { return nullptr; }
    };

    template<class T, class D> struct CallDeleter {
        void operator()(D deleter, T* data, std::size_t size) const {
            deleter(data, size);
        }
    };
    template<class T> struct CallDeleter<T, void(*)(T*, std::size_t)> {
        void operator()(void(*deleter)(T*, std::size_t), T* data, std::size_t size) const {
            if(deleter) deleter(data, size);
            else delete[] data;
        }
    };

    template<class T> T* noInitAllocate(std::size_t size, typename std::enable_if<std::is_trivial<T>::value>::type* = nullptr) {
        return new T[size];
    }
    template<class T> T* noInitAllocate(std::size_t size, typename std::enable_if<!std::is_trivial<T>::value>::type* = nullptr) {
        return reinterpret_cast<T*>(new char[size*sizeof(T)]);
    }

    template<class T> auto noInitDeleter(typename std::enable_if<std::is_trivial<T>::value>::type* = nullptr) -> void(*)(T*, std::size_t) {
        return nullptr; /* using the default deleter for T */
    }
    template<class T> auto noInitDeleter(typename std::enable_if<!std::is_trivial<T>::value>::type* = nullptr) -> void(*)(T*, std::size_t) {
        return [](T* data, std::size_t size) {
            if(data) for(T *it = data, *end = data + size; it != end; ++it)
                it->~T();
            delete[] reinterpret_cast<char*>(data);
        };
    }
}

/**
@brief Array wrapper with size information
@tparam T   Element type
@tparam D   Deleter type. Defaults to pointer to a @cpp void(T*, std::size_t) @ce
    function, where first is array pointer and second array size

Provides a RAII wrapper around a plain C array. A lighter alternative to
@ref std::vector that's deliberately move-only to avoid accidental copies of
large memory blocks. It's usable in STL algorithms in the same way as a plain C
array as well as in range-for cycles and other APIs operating with iterators.
By default the array has a non-changeable size by default and growing
functionality is opt-in, see @ref Containers-Array-growable below for more
information. Usage example:

@snippet Containers.cpp Array-usage

@section Containers-Array-initialization Array initialization

The array is by default *value-initialized*, which means that trivial types
are zero-initialized and the default constructor is called on other types. It
is possible to initialize the array in a different way using so-called *tags*:

-   @ref Array(DefaultInitT, std::size_t) leaves trivial types uninitialized
    and calls the default constructor elsewhere. In other words,
    @cpp new T[size] @ce.
-   @ref Array(ValueInitT, std::size_t) is equivalent to the default case,
    zero-initializing trivial types and calling the default constructor
    elsewhere. Useful when you want to make the choice appear explicit. In
    other words, @cpp new T[size]{} @ce.
-   @ref Array(DirectInitT, std::size_t, Args&&... args) constructs all
    elements of the array using provided arguments. In other words,
    @cpp new T[size]{T{args...}, T{args...}, …} @ce.
-   @ref Array(InPlaceInitT, std::initializer_list<T>) allocates unitialized
    memory and then copy-constructs all elements from the initializer list. In
    other words, @cpp new T[size]{args...} @ce.
-   @ref Array(NoInitT, std::size_t) does not initialize anything and you need
    to call the constructor on all elements manually using placement new,
    @ref std::uninitialized_copy() or similar. This is the dangerous option.
    In other words, @cpp new char[size*sizeof(T)] @ce for non-trivial types
    to circumvent default construction and @cpp new T[size] @ce for trivial
    types.

Example:

@snippet Containers.cpp Array-initialization

@section Containers-Array-wrapping Wrapping externally allocated arrays

By default the class makes all allocations using @cpp operator new[] @ce and
deallocates using @cpp operator delete[] @ce for given @p T, with some
additional trickery done internally to make the @ref Array(NoInitT, std::size_t)
and @ref Array(DirectInitT, std::size_t, Args&&... args) constructors work.
When wrapping an externally allocated array using @ref Array(T*, std::size_t, D),
it is possible to specify which function to use for deallocation. By default
the deleter is set to @cpp nullptr @ce, which is equivalent to deleting the
contents using @cpp operator delete[] @ce.

For example, properly deallocating array allocated using @ref std::malloc():

@snippet Containers.cpp Array-wrapping

By default, plain function pointers are used to avoid having the type affected
by the deleter function. If the deleter needs to manage some state, a custom
deleter type can be used:

@snippet Containers.cpp Array-deleter

@section Containers-Array-growable Growable arrays

The @ref Array class provides no reallocation or growing capabilities on its
own, and this functionality is opt-in via free functions from
@ref Corrade/Containers/GrowableArray.h instead. This is done in order to keep
the concept of an owning container decoupled from the extra baggage coming from
custom allocators, type constructibility and such.

As long as the type stored in the array is nothrow-move-constructible, any
@ref Array instance can be converted to a growing container by calling the
family of @ref arrayAppend(), @ref arrayReserve(), @ref arrayResize() ...
functions. A growable array behaves the same as a regular array to its
consumers --- its @ref size() returns the count of *real* elements, while
available capacity can be queried through @ref arrayCapacity(). Example of
populating an array with an undetermined amount of elements:

@snippet Containers.cpp Array-growable

A growable array can be turned back into a regular one using
@ref arrayShrink() if desired. That'll free all extra memory, moving the
elements to an array of exactly the size needed.

@m_class{m-block m-success}

@par Tip
    To save typing, you can make use of ADL and call the @ref arrayAppend()
    etc. functions unqualified, without having them explicitly prefixed with
    @cpp Containers:: @ce.

@subsection Containers-Array-growable-allocators Growable allocators

Similarly to standard containers, growable arrays allow you to use a custom
allocator that matches the documented semantics of @ref ArrayAllocator. It's
also possible to switch between different allocators during the lifetime of an
@ref Array instance --- internally it's the same process as when a non-growable
array is converted to a growable version (or back, with @ref arrayShrink()).

The @ref ArrayAllocator is by default aliased to @ref ArrayNewAllocator, which
uses the standard C++ @cpp new[] @ce / @cpp delete[] @ce constructs and is
fully move-aware, requiring the types to be only nothrow-move-constructible at
the very least. If a type is trivially copyable, the @ref ArrayMallocAllocator
will get picked instead, make use of @ref std::realloc() to avoid unnecessary
memory copies when growing the array. The typeless nature of
@ref ArrayMallocAllocator internals allows for free type-casting of the array
instance with @ref arrayAllocatorCast(), an operation not easily doable using
typed allocators.

@subsection Containers-Array-growable-sanitizer AddressSanitizer container annotations

Because the alloacted growable arrays have an area between @ref size() and
@ref arrayCapacity() that shouldn't be accessed, when building with
[Address Sanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizer)
enabled, this area is marked as "container overflow". Given the following code,
ASan aborts and produces a failure report similar to the one below:

@m_class{m-code-figure}

@parblock

@snippet Containers.cpp Array-growable-sanitizer

<p></p>

@m_class{m-nopad}

@include containers-growable-array-sanitizer.ansi

@endparblock

@section Containers-Array-views Conversion to array views

Arrays are implicitly convertible to @ref ArrayView as described in the
following table. The conversion is only allowed if @cpp T* @ce is implicitly
convertible to @cpp U* @ce (or both are the same type) and both have the same
size. This also extends to other container types constructibe from
@ref ArrayView, which means for example that a @ref StridedArrayView1D is
implicitly convertible from @ref Array as well.

Owning array type               | ↭ | Non-owning view type
------------------------------- | - | ---------------------
@ref Array "Array<T>"           | → | @ref ArrayView "ArrayView<U>"
@ref Array "Array<T>"           | → | @ref ArrayView "ArrayView<const U>"
@ref Array "const Array<T>"     | → | @ref ArrayView "ArrayView<const U>"

@section Containers-Array-stl STL compatibility

On compilers that support C++2a and @ref std::span, implicit conversion of an
@ref Array to it is provided in @ref Corrade/Containers/ArrayViewStlSpan.h. The
conversion is provided in a separate header to avoid unconditional
@cpp #include <span> @ce, which significantly affects compile times. The
following table lists allowed conversions:

Corrade type                    | ↭ | STL type
------------------------------- | - | ---------------------
@ref Array "Array<T>"           | → | @ref std::span "std::span<T>"
@ref Array "Array<T>"           | → | @ref std::span "std::span<const T>"
@ref Array "const Array<T>"     | → | @ref std::span "std::span<const T>"

There are some dangerous corner cases due to the way @ref std::span is
designed, see @ref Containers-ArrayView-stl "ArrayView STL compatibility" for
more information.

@m_class{m-block m-success}

@par Single-header version
    This class, together with @ref StaticArray, is also available as a
    single-header [CorradeArray.h](https://github.com/mosra/magnum-singles/tree/master/CorradeArray.h)
    library in the Magnum Singles repository for easier integration into your
    projects. See @ref corrade-singles for more information.

@see @ref arrayCast(Array<T, D>&), @ref StaticArray
*/
#ifdef DOXYGEN_GENERATING_OUTPUT
template<class T, class D = void(*)(T*, std::size_t)>
#else
template<class T, class D>
#endif
class Array {
    /* Ideally this could be derived from ArrayView<T>, avoiding a lot of
       redundant code, however I'm unable to find a way to add const/non-const
       overloads of all slicing functions and also prevent const Array<T>& from
       being sliced to a (mutable) ArrayView<T>. */

    public:
        typedef T Type;     /**< @brief Element type */
        typedef D Deleter;  /**< @brief Deleter type */

        /** @brief Conversion from nullptr */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        /*implicit*/ Array(std::nullptr_t) noexcept:
        #else
        template<class U, class V = typename std::enable_if<std::is_same<std::nullptr_t, U>::value>::type> /*implicit*/ Array(U) noexcept:
        #endif
            /* GCC <=4.8 breaks on _deleter{} */
            _data{nullptr}, _size{0}, _deleter(Implementation::DefaultDeleter<D>{}()) {}

        /**
         * @brief Default constructor
         *
         * Creates a zero-sized array. Move an array with a nonzero size onto
         * the instance to make it useful.
         */
        /* GCC <=4.8 breaks on _deleter{} */
        /*implicit*/ Array() noexcept: _data(nullptr), _size(0), _deleter(Implementation::DefaultDeleter<D>{}()) {}

        /**
         * @brief Construct a default-initialized array
         *
         * Creates array of given size, the contents are default-initialized
         * (i.e. builtin types are not initialized). If the size is zero, no
         * allocation is done.
         * @see @ref DefaultInit, @ref Array(ValueInitT, std::size_t)
         */
        explicit Array(DefaultInitT, std::size_t size): _data{size ? new T[size] : nullptr}, _size{size}, _deleter{nullptr} {}

        /**
         * @brief Construct a value-initialized array
         *
         * Creates array of given size, the contents are value-initialized
         * (i.e. builtin types are zero-initialized). For other than builtin
         * types this is the same as @ref Array(std::size_t). If the size is
         * zero, no allocation is done.
         *
         * Useful if you want to create an array of primitive types and set
         * them to zero.
         * @see @ref ValueInit, @ref Array(DefaultInitT, std::size_t)
         */
        explicit Array(ValueInitT, std::size_t size): _data{size ? new T[size]() : nullptr}, _size{size}, _deleter{nullptr} {}

        /**
         * @brief Construct an array without initializing its contents
         *
         * Creates array of given size, the contents are *not* initialized. If
         * the size is zero, no allocation is done. Initialize the values using
         * placement new. Useful if you will be overwriting all elements later
         * anyway.
         *
         * -    For non-trivial types, the data are allocated as a
         *      @cpp char @ce array. Destruction is done using a custom deleter
         *      that explicitly calls destructor on *all elements* (regardless
         *      of whether they were properly constructed or not) and then
         *      deallocates the data as a @cpp char @ce array again.
         * -    For trivial types is equivalent to
         *      @ref Array(DefaultInitT, std::size_t), with @ref deleter()
         *      being the default (@cpp nullptr @ce) as well. This is done in
         *      order to avoid needless problems with dangling custom deleters
         *      when returning arrays from dynamically loaded libraries.
         *
         * @see @ref NoInit, @ref Array(DirectInitT, std::size_t, Args&&... args),
         *      @ref deleter(), @ref std::is_trivial
         */
        explicit Array(NoInitT, std::size_t size): _data{size ? Implementation::noInitAllocate<T>(size) : nullptr}, _size{size}, _deleter{Implementation::noInitDeleter<T>()} {}

        /**
         * @brief Construct a direct-initialized array
         *
         * Allocates the array using the @ref Array(NoInitT, std::size_t)
         * constructor and then initializes each element with placement new
         * using forwarded @p args.
         */
        template<class... Args> explicit Array(DirectInitT, std::size_t size, Args&&... args);

        /**
         * @brief Construct a list-initialized array
         *
         * Allocates the array using the @ref Array(NoInitT, std::size_t)
         * constructor and then copy-initializes each element with placement
         * new using values from @p list.
         *
         * Note that there's no plain initializer-list constructor because it
         * would cause a similar fiasco as with @ref std::vector, where
         * @cpp std::vector<int>{5} @ce creates one-element vector but
         * @cpp std::vector<int>(5) @ce creates a zero-initialized five-element
         * vector. To save typing, you can use the
         * @ref array(std::initializer_list<T>) helper which doesn't suffer
         * from this problem.
         */
        explicit Array(InPlaceInitT, std::initializer_list<T> list);

        /**
         * @brief Construct a value-initialized array
         *
         * Alias to @ref Array(ValueInitT, std::size_t).
         * @see @ref Array(DefaultInitT, std::size_t)
         */
        explicit Array(std::size_t size): Array{ValueInit, size} {}

        /**
         * @brief Wrap an existing array
         *
         * Note that the array will be deleted on destruction using given
         * @p deleter. See class documentation for more information about
         * custom deleters and @ref ArrayView for non-owning array wrapper.
         */
        /* GCC <=4.8 breaks on _deleter{} */
        explicit Array(T* data, std::size_t size, D deleter = Implementation::DefaultDeleter<D>{}()): _data{data}, _size{size}, _deleter(deleter) {}

        /**
         * @brief Destructor
         *
         * Calls @ref deleter() on the owned @ref data().
         */
        ~Array() { Implementation::CallDeleter<T, D>{}(_deleter, _data, _size); }

        /** @brief Copying is not allowed */
        Array(const Array<T, D>&) = delete;

        /**
         * @brief Move constructor
         *
         * Resets data pointer, size and deleter of @p other to be equivalent
         * to a default-constructed instance.
         */
        Array(Array<T, D>&& other) noexcept;

        /** @brief Copying is not allowed */
        Array<T, D>& operator=(const Array<T, D>&) = delete;

        /**
         * @brief Move assignment
         *
         * Swaps data pointer, size and deleter of the two instances.
         */
        Array<T, D>& operator=(Array<T, D>&& other) noexcept;

        /* The following view conversion is *not* restricted to this& because
           that would break uses like `consume(foo());`, where `consume()`
           expects a view but `foo()` returns an owning array. */

        /**
         * @brief Convert to external view representation
         *
         * @see @ref Containers-Array-stl
         */
        template<class U, class = decltype(Implementation::ArrayViewConverter<T, U>::to(std::declval<ArrayView<T>>()))> /*implicit*/ operator U() {
            return Implementation::ArrayViewConverter<T, U>::to(*this);
        }

        /** @overload */
        template<class U, class = decltype(Implementation::ArrayViewConverter<const T, U>::to(std::declval<ArrayView<const T>>()))> constexpr /*implicit*/ operator U() const {
            return Implementation::ArrayViewConverter<const T, U>::to(*this);
        }

        #ifndef CORRADE_MSVC2019_COMPATIBILITY
        /** @brief Whether the array is non-empty */
        /* Disabled on MSVC <= 2017 to avoid ambiguous operator+() when doing
           pointer arithmetic. On MSVC 2019 this works properly when
           /permissive- is enabled, but I can neither detect a presence of that
           flag nor force it for all users (since it often ICEs and breaks 3rd
           party code), so disabling for 2019 as well. */
        explicit operator bool() const { return _data; }
        #endif

        /* `char* a = Containers::Array<char>(5); a[3] = 5;` would result in
           instant segfault, disallowing it in the following conversion
           operators */

        /** @brief Conversion to array type */
        /*implicit*/ operator T*() & { return _data; }

        /** @overload */
        /*implicit*/ operator const T*() const & { return _data; }

        /** @brief Array data */
        T* data() { return _data; }
        const T* data() const { return _data; }         /**< @overload */

        /**
         * @brief Array deleter
         *
         * If set to @cpp nullptr @ce, the contents are deleted using standard
         * @cpp operator delete[] @ce.
         * @see @ref Array(T*, std::size_t, D)
         */
        D deleter() const { return _deleter; }

        /** @brief Array size */
        std::size_t size() const { return _size; }

        /** @brief Whether the array is empty */
        bool empty() const { return !_size; }

        /**
         * @brief Pointer to first element
         *
         * @see @ref front()
         */
        T* begin() { return _data; }
        const T* begin() const { return _data; }        /**< @overload */
        const T* cbegin() const { return _data; }       /**< @overload */

        /**
         * @brief Pointer to (one item after) last element
         *
         * @see @ref back()
         */
        T* end() { return _data+_size; }
        const T* end() const { return _data+_size; }    /**< @overload */
        const T* cend() const { return _data+_size; }   /**< @overload */

        /**
         * @brief First element
         *
         * Expects there is at least one element.
         * @see @ref begin()
         */
        T& front();
        const T& front() const; /**< @overload */

        /**
         * @brief Last element
         *
         * Expects there is at least one element.
         * @see @ref end()
         */
        T& back();
        const T& back() const; /**< @overload */

        /**
         * @brief Reference to array slice
         *
         * Equivalent to @ref ArrayView::slice().
         */
        ArrayView<T> slice(T* begin, T* end) {
            return ArrayView<T>(*this).slice(begin, end);
        }
        /** @overload */
        ArrayView<const T> slice(const T* begin, const T* end) const {
            return ArrayView<const T>(*this).slice(begin, end);
        }
        /** @overload */
        ArrayView<T> slice(std::size_t begin, std::size_t end) {
            return ArrayView<T>(*this).slice(begin, end);
        }
        /** @overload */
        ArrayView<const T> slice(std::size_t begin, std::size_t end) const {
            return ArrayView<const T>(*this).slice(begin, end);
        }

        /**
         * @brief Fixed-size array slice
         *
         * Both @cpp begin @ce and @cpp begin + size @ce are expected to be in
         * range.
         */
        template<std::size_t size> StaticArrayView<size, T> slice(T* begin) {
            return ArrayView<T>(*this).template slice<size>(begin);
        }
        /** @overload */
        template<std::size_t size> StaticArrayView<size, const T> slice(const T* begin) const {
            return ArrayView<const T>(*this).template slice<size>(begin);
        }
        /** @overload */
        template<std::size_t size> StaticArrayView<size, T> slice(std::size_t begin) {
            return ArrayView<T>(*this).template slice<size>(begin);
        }
        /** @overload */
        template<std::size_t size> StaticArrayView<size, const T> slice(std::size_t begin) const {
            return ArrayView<const T>(*this).template slice<size>(begin);
        }

        /**
         * @brief Fixed-size array slice
         * @m_since{2019,10}
         *
         * At compile time expects that @cpp begin < end_ @ce, at runtime that
         * @p end_ is not larger than @ref size().
         */
        template<std::size_t begin_, std::size_t end_> StaticArrayView<end_ - begin_, T> slice() {
            return ArrayView<T>(*this).template slice<begin_, end_>();
        }

        /**
         * @overload
         * @m_since{2019,10}
         */
        template<std::size_t begin_, std::size_t end_> StaticArrayView<end_ - begin_, const T> slice() const {
            return ArrayView<const T>(*this).template slice<begin_, end_>();
        }

        /**
         * @brief Array prefix
         *
         * Equivalent to @ref ArrayView::prefix().
         */
        ArrayView<T> prefix(T* end) {
            return ArrayView<T>(*this).prefix(end);
        }
        /** @overload */
        ArrayView<const T> prefix(const T* end) const {
            return ArrayView<const T>(*this).prefix(end);
        }
        /** @overload */
        ArrayView<T> prefix(std::size_t end) {
            return ArrayView<T>(*this).prefix(end);
        }
        /** @overload */
        ArrayView<const T> prefix(std::size_t end) const {
            return ArrayView<const T>(*this).prefix(end);
        }

        /** @overload */
        template<std::size_t viewSize> StaticArrayView<viewSize, T> prefix() {
            return ArrayView<T>(*this).template prefix<viewSize>();
        }
        /** @overload */
        template<std::size_t viewSize> StaticArrayView<viewSize, const T> prefix() const {
            return ArrayView<const T>(*this).template prefix<viewSize>();
        }

        /**
         * @brief Array suffix
         *
         * Equivalent to @ref ArrayView::suffix().
         */
        ArrayView<T> suffix(T* begin) {
            return ArrayView<T>(*this).suffix(begin);
        }
        /** @overload */
        ArrayView<const T> suffix(const T* begin) const {
            return ArrayView<const T>(*this).suffix(begin);
        }
        /** @overload */
        ArrayView<T> suffix(std::size_t begin) {
            return ArrayView<T>(*this).suffix(begin);
        }
        /** @overload */
        ArrayView<const T> suffix(std::size_t begin) const {
            return ArrayView<const T>(*this).suffix(begin);
        }

        /**
         * @brief Array prefix except the last @p count items
         * @m_since{2019,10}
         *
         * Equivalent to @ref ArrayView::except().
         */
        ArrayView<T> except(std::size_t count) {
            return ArrayView<T>(*this).except(count);
        }
        /**
         * @overload
         * @m_since{2019,10}
         */
        ArrayView<const T> except(std::size_t count) const {
            return ArrayView<const T>(*this).except(count);
        }

        /**
         * @brief Release data storage
         *
         * Returns the data pointer and resets data pointer, size and deleter
         * to be equivalent to a default-constructed instance. Deleting the
         * returned array is user responsibility --- note the array might have
         * a custom @ref deleter() and so @cpp delete[] @ce might not be always
         * appropriate.
         */
        T* release();

    private:
        T* _data;
        std::size_t _size;
        D _deleter;
};

/** @relatesalso Array
@brief Construct a list-initialized array
@m_since{2020,06}

Convenience shortcut to the @ref Array::Array(InPlaceInitT, std::initializer_list<T>)
constructor. See its documentation for a design rationale.
*/
template<class T> inline Array<T> array(std::initializer_list<T> list) {
    return Array<T>{InPlaceInit, list};
}

/** @relatesalso ArrayView
@brief Make view on @ref Array

Convenience alternative to converting to an @ref ArrayView explicitly. The
following two lines are equivalent:

@snippet Containers.cpp Array-arrayView
*/
template<class T, class D> inline ArrayView<T> arrayView(Array<T, D>& array) {
    return ArrayView<T>{array};
}

/** @relatesalso ArrayView
@brief Make view on const @ref Array

Convenience alternative to converting to an @ref ArrayView explicitly. The
following two lines are equivalent:

@snippet Containers.cpp Array-arrayView-const
*/
template<class T, class D> inline ArrayView<const T> arrayView(const Array<T, D>& array) {
    return ArrayView<const T>{array};
}

/** @relatesalso Array
@brief Reinterpret-cast an array

See @ref arrayCast(ArrayView<T>) for more information.
*/
template<class U, class T, class D> inline ArrayView<U> arrayCast(Array<T, D>& array) {
    return arrayCast<U>(arrayView(array));
}

/** @overload */
template<class U, class T, class D> inline ArrayView<const U> arrayCast(const Array<T, D>& array) {
    return arrayCast<const U>(arrayView(array));
}

/** @relatesalso Array
@brief Array size

See @ref arraySize(ArrayView<T>) for more information.
*/
template<class T> std::size_t arraySize(const Array<T>& view) {
    return view.size();
}

template<class T, class D> inline Array<T, D>::Array(Array<T, D>&& other) noexcept: _data{other._data}, _size{other._size}, _deleter{other._deleter} {
    other._data = nullptr;
    other._size = 0;
    other._deleter = D{};
}

template<class T, class D> template<class ...Args> Array<T, D>::Array(DirectInitT, std::size_t size, Args&&... args): Array{NoInit, size} {
    for(std::size_t i = 0; i != size; ++i)
        Implementation::construct(_data[i], std::forward<Args>(args)...);
}

template<class T, class D> Array<T, D>::Array(InPlaceInitT, std::initializer_list<T> list): Array{NoInit, list.size()} {
    std::size_t i = 0;
    for(const T& item: list) new(_data + i++) T{item};
}

template<class T, class D> inline Array<T, D>& Array<T, D>::operator=(Array<T, D>&& other) noexcept {
    using std::swap;
    swap(_data, other._data);
    swap(_size, other._size);
    swap(_deleter, other._deleter);
    return *this;
}

template<class T, class D> const T& Array<T, D>::front() const {
    CORRADE_ASSERT(_size, "Containers::Array::front(): array is empty", _data[0]);
    return _data[0];
}

template<class T, class D> const T& Array<T, D>::back() const {
    CORRADE_ASSERT(_size, "Containers::Array::back(): array is empty", _data[_size - 1]);
    return _data[_size - 1];
}

template<class T, class D> T& Array<T, D>::front() {
    return const_cast<T&>(static_cast<const Array<T, D>&>(*this).front());
}

template<class T, class D> T& Array<T, D>::back() {
    return const_cast<T&>(static_cast<const Array<T, D>&>(*this).back());
}

template<class T, class D> inline T* Array<T, D>::release() {
    T* const data = _data;
    _data = nullptr;
    _size = 0;
    _deleter = D{};
    return data;
}

namespace Implementation {

/* Array to ArrayView in order to have implicit conversion for StridedArrayView
   without needing to introduce a header dependency. The SFINAE needs to be
   here in order to ensure proper behavior with function overloads taking more
   than one type of (Strided)ArrayView. */
template<class U, class T, class D> struct ArrayViewConverter<U, Array<T, D>> {
    template<class V = U> constexpr static typename std::enable_if<std::is_convertible<T*, V*>::value, ArrayView<U>>::type from(Array<T, D>& other) {
        static_assert(sizeof(T) == sizeof(U), "types are not compatible");
        return {&other[0], other.size()};
    }
    template<class V = U> constexpr static typename std::enable_if<std::is_convertible<T*, V*>::value, ArrayView<U>>::type from(Array<T, D>&& other) {
        static_assert(sizeof(T) == sizeof(U), "types are not compatible");
        return {&other[0], other.size()};
    }
};
template<class U, class T, class D> struct ArrayViewConverter<const U, Array<T, D>> {
    template<class V = U> constexpr static typename std::enable_if<std::is_convertible<T*, V*>::value, ArrayView<const U>>::type from(const Array<T, D>& other) {
        static_assert(sizeof(T) == sizeof(U), "types are not compatible");
        return {&other[0], other.size()};
    }
};
template<class U, class T, class D> struct ArrayViewConverter<const U, Array<const T, D>> {
    template<class V = U> constexpr static typename std::enable_if<std::is_convertible<T*, V*>::value, ArrayView<const U>>::type from(const Array<const T, D>& other) {
        static_assert(sizeof(T) == sizeof(U), "types are not compatible");
        return {&other[0], other.size()};
    }
};
template<class T, class D> struct ErasedArrayViewConverter<Array<T, D>>: ArrayViewConverter<T, Array<T, D>> {};
template<class T, class D> struct ErasedArrayViewConverter<const Array<T, D>>: ArrayViewConverter<const T, Array<T, D>> {};

}

}}

#endif