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2026-09-16 14:07:40 +08:00

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3.7 KiB
C++
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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
#pragma once
JPH_NAMESPACE_BEGIN
/// Default implementation of AllocatorHasReallocate which tells if an allocator has a reallocate function
template <class T> struct AllocatorHasReallocate { static constexpr bool sValue = false; };
#ifndef JPH_DISABLE_CUSTOM_ALLOCATOR
/// STL allocator that forwards to our allocation functions
template <typename T>
class STLAllocator
{
public:
using value_type = T;
/// Pointer to type
using pointer = T *;
using const_pointer = const T *;
/// Reference to type.
/// Can be removed in C++20.
using reference = T &;
using const_reference = const T &;
using size_type = size_t;
using difference_type = ptrdiff_t;
/// The allocator is stateless
using is_always_equal = std::true_type;
/// Allocator supports moving
using propagate_on_container_move_assignment = std::true_type;
/// Constructor
inline STLAllocator() = default;
/// Constructor from other allocator
template <typename T2>
inline STLAllocator(const STLAllocator<T2> &) { }
/// If this allocator needs to fall back to aligned allocations because the type requires it
static constexpr bool needs_aligned_allocate = alignof(T) > JPH_DEFAULT_ALLOCATE_ALIGNMENT;
/// Allocate memory
inline pointer allocate(size_type inN)
{
if constexpr (needs_aligned_allocate)
return pointer(AlignedAllocate(inN * sizeof(value_type), alignof(T)));
else
return pointer(Allocate(inN * sizeof(value_type)));
}
/// Should we expose a reallocate function?
static constexpr bool has_reallocate = std::is_trivially_copyable<T>() && !needs_aligned_allocate;
/// Reallocate memory
template <bool has_reallocate_v = has_reallocate, typename = std::enable_if_t<has_reallocate_v>>
inline pointer reallocate(pointer inOldPointer, size_type inOldSize, size_type inNewSize)
{
JPH_ASSERT(inNewSize > 0); // Reallocating to zero size is implementation dependent, so we don't allow it
return pointer(Reallocate(inOldPointer, inOldSize * sizeof(value_type), inNewSize * sizeof(value_type)));
}
/// Free memory
inline void deallocate(pointer inPointer, size_type)
{
if constexpr (needs_aligned_allocate)
AlignedFree(inPointer);
else
Free(inPointer);
}
/// Allocators are stateless so assumed to be equal
inline bool operator == (const STLAllocator<T> &) const
{
return true;
}
inline bool operator != (const STLAllocator<T> &) const
{
return false;
}
/// Converting to allocator for other type
template <typename T2>
struct rebind
{
using other = STLAllocator<T2>;
};
};
/// The STLAllocator implements the reallocate function if the alignment of the class is smaller or equal to the default alignment for the platform
template <class T> struct AllocatorHasReallocate<STLAllocator<T>> { static constexpr bool sValue = STLAllocator<T>::has_reallocate; };
#else
template <typename T> using STLAllocator = std::allocator<T>;
#endif // !JPH_DISABLE_CUSTOM_ALLOCATOR
// Declare STL containers that use our allocator
using String = std::basic_string<char, std::char_traits<char>, STLAllocator<char>>;
using IStringStream = std::basic_istringstream<char, std::char_traits<char>, STLAllocator<char>>;
JPH_NAMESPACE_END
#if (!defined(JPH_PLATFORM_WINDOWS) || defined(JPH_COMPILER_MINGW)) && !defined(JPH_DISABLE_CUSTOM_ALLOCATOR)
namespace std
{
/// Declare std::hash for String, for some reason on Linux based platforms template deduction takes the wrong variant
template <>
struct hash<JPH::String>
{
inline size_t operator () (const JPH::String &inRHS) const
{
return hash<string_view> { } (inRHS);
}
};
}
#endif // (!JPH_PLATFORM_WINDOWS || JPH_COMPILER_MINGW) && !JPH_DISABLE_CUSTOM_ALLOCATOR