allocator_adapters.h

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/* Copyright (c) 2011 Wildfire Games
 *
 * 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.
 */

/*
 * adapters for allocators; provides a minimal subset of the
 * STL allocator interface.
 */

#ifndef ALLOCATOR_ADAPTERS
#define ALLOCATOR_ADAPTERS

#include <memory>

#include "lib/sysdep/rtl.h"
#include "lib/sysdep/vm.h"

// NB: STL allocators are parameterized on the object type and indicate
// the number of elements to [de]allocate. however, these adapters are
// only used for allocating storage and receive the number of bytes.

struct Allocator_Heap
{
    void* allocate(size_t size)
    {
        return malloc(size);
    }

    void deallocate(void* p, size_t UNUSED(size))
    {
        return free(p);
    }
};

template<size_t alignment = allocationAlignment>
struct Allocator_Aligned
{
    void* allocate(size_t size)
    {
        return rtl_AllocateAligned(size, alignment);
    }

    void deallocate(void* p, size_t UNUSED(size))
    {
        return rtl_FreeAligned(p);
    }
};

template<vm::PageType pageType = vm::kDefault, int prot = PROT_READ|PROT_WRITE>
struct Allocator_VM
{
    void* allocate(size_t size)
    {
        return vm::Allocate(size, pageType, prot);
    }

    void deallocate(void* p, size_t size)
    {
        vm::Free(p, size);
    }
};

template<size_t commitSize = largePageSize, vm::PageType pageType = vm::kDefault, int prot = PROT_READ|PROT_WRITE>
struct Allocator_AddressSpace
{
    void* allocate(size_t size)
    {
        return vm::ReserveAddressSpace(size, commitSize, pageType, prot);
    }

    void deallocate(void* p, size_t size)
    {
        vm::ReleaseAddressSpace(p, size);
    }
};


/**
 * fully STL-compatible allocator that simply draws upon another Allocator.
 * this allows a single allocator to serve multiple STL containers.
 */
template<typename T, class Allocator>
class ProxyAllocator
{
public:
    typedef T value_type;
    typedef T* pointer;
    typedef const T* const_pointer;
    typedef T& reference;
    typedef const T& const_reference;
    typedef std::size_t size_type;
    typedef std::ptrdiff_t difference_type;

    template<class U>
    struct rebind
    {
        typedef ProxyAllocator<U, Allocator> other;
    };

    // (required to be declared by boost::unordered_map, but should never be called)
    explicit NOTHROW_DEFINE ProxyAllocator();

    explicit NOTHROW_DEFINE ProxyAllocator(Allocator& allocator)
        : allocator(&allocator)
    {
    }

    template<typename U, class A>
    NOTHROW_DEFINE ProxyAllocator(const ProxyAllocator<U,A>& rhs)
        : allocator(rhs.allocator)
    {
    }
    
    // (required by VC2010 std::vector)
    bool operator==(const ProxyAllocator& rhs) const
    {
        return allocator == rhs.allocator;
    }
    bool operator!=(const ProxyAllocator& rhs) const
    {
        return !operator==(rhs);
    }

    pointer address(reference r)
    {
        return &r;
    }

    const_pointer address(const_reference s)
    {
        return &s;
    }

    size_type max_size() const throw ()
    {
        return std::numeric_limits<std::size_t>::max() / sizeof(T);
    }

    void construct(const pointer ptr, const value_type& t)
    {
        new(ptr) T(t);
    }

    void destroy(pointer ptr)
    {
        ptr->~T();
        UNUSED2(ptr); // silence MSVC warnings
    }

    pointer allocate(size_type n)
    {
        // safely handle zero-sized allocations (happens with GCC STL - see ticket #909).
        if(n == 0)
            n = 1;
        return (pointer)allocator->allocate(n*sizeof(T));
    }

    pointer allocate(size_type n, const void* const)
    {
        return allocate(n);
    }

    void deallocate(const pointer ptr, const size_type n)
    {
        return allocator->deallocate(ptr, n*sizeof(T));
    }

//private:  // otherwise copy ctor cannot access it
    Allocator* allocator;
};

#endif  // #ifndef ALLOCATOR_ADAPTERS