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////////////////////////////////////////////////////////////////////////////////
// The Loki Library
// Copyright (c) 2008 by Rich Sposato
//
// Permission to use, copy, modify, distribute and sell this software for any
// purpose is hereby granted without fee, provided that the above copyright
// notice appear in all copies and that both that copyright notice and this
// permission notice appear in supporting documentation.
// The author makes no representations about the
// suitability of this software for any purpose. It is provided "as is"
// without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////
#ifndef LOKI_ALLOCATOR_HPP_INCLUDED
#define LOKI_ALLOCATOR_HPP_INCLUDED
// $Id: Allocator.h 896 2008-08-08 22:20:05Z syntheticpp $
// Requires project to be compiled with loki/src/SmallObj.cpp and loki/src/Singleton.cpp
#include <loki/SmallObj.h>
namespace Loki
{
//-----------------------------------------------------------------------------
/** @class LokiAllocator
Adapts Loki's Small-Object Allocator for STL container classes.
This class provides all the functionality required for STL allocators, but
uses Loki's Small-Object Allocator to perform actual memory operations.
Implementation comes from a post in Loki forums (by Rasmus Ekman?).
*/
template
<
typename Type,
typename AllocT = Loki::AllocatorSingleton<>
>
class LokiAllocator
{
public:
typedef ::std::size_t size_type;
typedef ::std::ptrdiff_t difference_type;
typedef Type * pointer;
typedef const Type * const_pointer;
typedef Type & reference;
typedef const Type & const_reference;
typedef Type value_type;
/// Default constructor does nothing.
inline LokiAllocator( void ) throw() { }
/// Copy constructor does nothing.
inline LokiAllocator( const LokiAllocator & ) throw() { }
/// Type converting allocator constructor does nothing.
template < typename Type1 >
inline LokiAllocator( const LokiAllocator< Type1 > & ) throw() { }
/// Destructor does nothing.
inline ~LokiAllocator() throw() { }
/// Convert an allocator<Type> to an allocator <Type1>.
template < typename Type1 >
struct rebind
{
typedef LokiAllocator< Type1 > other;
};
/// Return address of reference to mutable element.
pointer address( reference elem ) const { return &elem; }
/// Return address of reference to const element.
const_pointer address( const_reference elem ) const { return &elem; }
/** Allocate an array of count elements. Warning! The true parameter in
the call to Allocate means this function can throw exceptions. This is
better than not throwing, and returning a null pointer in case the caller
assumes the return value is not null.
@param count # of elements in array.
@param hint Place where caller thinks allocation should occur.
@return Pointer to block of memory.
*/
pointer allocate( size_type count, const void * hint = 0 )
{
(void)hint; // Ignore the hint.
void * p = AllocT::Instance().Allocate( count * sizeof( Type ), true );
return reinterpret_cast< pointer >( p );
}
/// Ask allocator to release memory at pointer with size bytes.
void deallocate( pointer p, size_type size )
{
AllocT::Instance().Deallocate( p, size * sizeof( Type ) );
}
/// Calculate max # of elements allocator can handle.
size_type max_size( void ) const throw()
{
// A good optimizer will see these calculations always produce the same
// value and optimize this function away completely.
const size_type max_bytes = size_type( -1 );
const size_type bytes = max_bytes / sizeof( Type );
return bytes;
}
/// Construct an element at the pointer.
void construct( pointer p, const Type & value )
{
// A call to global placement new forces a call to copy constructor.
::new( p ) Type( value );
}
/// Destruct the object at pointer.
void destroy( pointer p )
{
// If the Type has no destructor, then some compilers complain about
// an unreferenced parameter, so use the void cast trick to prevent
// spurious warnings.
(void)p;
p->~Type();
}
};
//-----------------------------------------------------------------------------
/** All equality operators return true since LokiAllocator is basically a
monostate design pattern, so all instances of it are identical.
*/
template < typename Type >
inline bool operator == ( const LokiAllocator< Type > &, const LokiAllocator< Type > & )
{
return true;
}
/** All inequality operators return false since LokiAllocator is basically a
monostate design pattern, so all instances of it are identical.
*/
template < typename Type >
inline bool operator != ( const LokiAllocator< Type > & , const LokiAllocator< Type > & )
{
return false;
}
//-----------------------------------------------------------------------------
} // namespace Loki
#endif // LOKI_ALLOCATOR_INCLUDED
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