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authorDaniel Wilhelm <daniel@wili.li>2014-04-18 17:01:29 +0200
committerDaniel Wilhelm <daniel@wili.li>2014-04-18 17:01:29 +0200
commit9a2a524f1e311853d08050be2dcdddc09ac7759a (patch)
treed8e4a24169fce88c2d89931d58514889a0bcb0ea /shared/loki/Allocator.h
parent2.3 (diff)
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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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