juce_HeapBlock.h

/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
#if ! (DOXYGEN || JUCE_EXCEPTIONS_DISABLED)
namespace HeapBlockHelper
{
    template <bool shouldThrow>
    struct ThrowOnFail          { static void checkPointer (void*) {} };
 
    template <>
    struct ThrowOnFail<true>    { static void checkPointer (void* data) { if (data == nullptr) throw std::bad_alloc(); } };
}
#endif
 
//==============================================================================
template <class ElementType, bool throwOnFailure = false>
class HeapBlock
{
private:
    template <class OtherElementType>
    using AllowConversion = std::enable_if_t<std::is_base_of_v<std::remove_pointer_t<ElementType>,
                                                               std::remove_pointer_t<OtherElementType>>>;
 
public:
    //==============================================================================
    HeapBlock() = default;

    template <typename SizeType, std::enable_if_t<std::is_convertible_v<SizeType, int>, int> = 0>
    explicit HeapBlock (SizeType numElements)
        : data (mallocWrapper (static_cast<size_t> (numElements) * sizeof (ElementType)))
    {
    }

    template <typename SizeType, std::enable_if_t<std::is_convertible_v<SizeType, int>, int> = 0>
    HeapBlock (SizeType numElements, bool initialiseToZero)
        : data (initialiseToZero ? callocWrapper (static_cast<size_t> (numElements), sizeof (ElementType))
                                 : mallocWrapper (static_cast<size_t> (numElements) * sizeof (ElementType)))
    {
    }

    ~HeapBlock()
    {
        std::free (data);
    }

    HeapBlock (HeapBlock&& other) noexcept
        : data (other.data)
    {
        other.data = nullptr;
    }

    HeapBlock& operator= (HeapBlock&& other) noexcept
    {
        std::swap (data, other.data);
        return *this;
    }

    template <class OtherElementType, bool otherThrowOnFailure, typename = AllowConversion<OtherElementType>>
    HeapBlock (HeapBlock<OtherElementType, otherThrowOnFailure>&& other) noexcept
        : data (reinterpret_cast<ElementType*> (other.data))
    {
        other.data = nullptr;
    }

    template <class OtherElementType, bool otherThrowOnFailure, typename = AllowConversion<OtherElementType>>
    HeapBlock& operator= (HeapBlock<OtherElementType, otherThrowOnFailure>&& other) noexcept
    {
        free();
        data = reinterpret_cast<ElementType*> (other.data);
        other.data = nullptr;
        return *this;
    }
 
    //==============================================================================
    inline operator ElementType*() const noexcept                            { return data; }

    inline ElementType* get() const noexcept                                 { return data; }

    inline ElementType* getData() const noexcept                             { return data; }

    inline operator void*() const noexcept                                   { return static_cast<void*> (data); }

    inline operator const void*() const noexcept                             { return static_cast<const void*> (data); }

    inline ElementType* operator->() const  noexcept                         { return data; }

    template <typename IndexType>
    ElementType& operator[] (IndexType index) const noexcept                 { return data [index]; }

    template <typename IndexType>
    ElementType* operator+ (IndexType index) const noexcept                  { return data + index; }
 
    //==============================================================================
    inline bool operator== (const ElementType* otherPointer) const noexcept  { return otherPointer == data; }

    inline bool operator!= (const ElementType* otherPointer) const noexcept  { return otherPointer != data; }
 
    //==============================================================================
    template <typename SizeType>
    void malloc (SizeType newNumElements, size_t elementSize = sizeof (ElementType))
    {
        std::free (data);
        data = mallocWrapper (static_cast<size_t> (newNumElements) * elementSize);
    }

    template <typename SizeType>
    void calloc (SizeType newNumElements, const size_t elementSize = sizeof (ElementType))
    {
        std::free (data);
        data = callocWrapper (static_cast<size_t> (newNumElements), elementSize);
    }

    template <typename SizeType>
    void allocate (SizeType newNumElements, bool initialiseToZero)
    {
        std::free (data);
        data = initialiseToZero ? callocWrapper (static_cast<size_t> (newNumElements), sizeof (ElementType))
                                : mallocWrapper (static_cast<size_t> (newNumElements) * sizeof (ElementType));
    }

    template <typename SizeType>
    void realloc (SizeType newNumElements, size_t elementSize = sizeof (ElementType))
    {
        data = reallocWrapper (data, static_cast<size_t> (newNumElements) * elementSize);
    }

    void free() noexcept
    {
        std::free (data);
        data = nullptr;
    }

    template <bool otherBlockThrows>
    void swapWith (HeapBlock<ElementType, otherBlockThrows>& other) noexcept
    {
        std::swap (data, other.data);
    }

    template <typename SizeType>
    void clear (SizeType numElements) noexcept
    {
        zeromem (data, sizeof (ElementType) * static_cast<size_t> (numElements));
    }

    using Type = ElementType;
 
private:
    //==============================================================================
    // Calls to malloc, calloc and realloc with zero size have implementation-defined
    // behaviour where either nullptr or a non-null pointer is returned.
    template <typename Functor>
    static ElementType* wrapper (size_t size, Functor&& f)
    {
        if (size == 0)
            return nullptr;
 
        auto* memory = static_cast<ElementType*> (f());
 
       #if JUCE_EXCEPTIONS_DISABLED
        jassert (memory != nullptr); // without exceptions, you'll need to find a better way to handle this failure case.
       #else
        HeapBlockHelper::ThrowOnFail<throwOnFailure>::checkPointer (memory);
       #endif
 
        return memory;
    }
 
    static ElementType* mallocWrapper (size_t size)
    {
        return wrapper (size, [size] { return std::malloc (size); });
    }
 
    static ElementType* callocWrapper (size_t num, size_t size)
    {
        return wrapper (num * size, [num, size] { return std::calloc (num, size); });
    }
 
    static ElementType* reallocWrapper (void* ptr, size_t newSize)
    {
        return wrapper (newSize, [ptr, newSize] { return std::realloc (ptr, newSize); });
    }
 
    template <class OtherElementType, bool otherThrowOnFailure>
    friend class HeapBlock;
 
    //==============================================================================
    ElementType* data = nullptr;
 
   #if ! (defined (JUCE_DLL) || defined (JUCE_DLL_BUILD))
    JUCE_DECLARE_NON_COPYABLE (HeapBlock)
    JUCE_PREVENT_HEAP_ALLOCATION // Creating a 'new HeapBlock' would be missing the point!
   #endif
};
 
} // namespace juce