occt/src/NCollection/NCollection_StdAllocator.hxx

// Author: Roman Lygin, 2012.
// This file is in the Public Domain and thus can freely be used for any purpose.
// The author disclaims any rights and liabilities.

#ifndef _NCollection_StdAllocator_HeaderFile
#define _NCollection_StdAllocator_HeaderFile

#include <NCollection_BaseAllocator.hxx>

#if _MSC_VER
  //Workaround for false "unreferenced parameter" warning in destroy().
  #pragma warning (push)
  #pragma warning (disable: 4100)
#endif

//! Implements allocator requirements as defined in ISO C++ Standard 2003, section 20.1.5.
/*! The allocator uses instance of the NCollection_BaseAllocator (sub)class for memory
  allocation/deallocation. The allocator can be used with standard
  containers (std::vector, std::map, etc) to take advantage of NCollection_IncAllocator
  which implements memory region concept, and hence to increase performance in specific
  cases.

  The underlying NCollection_BaseAllocator instance can be received using the Allocator()
  method.

  Example of use:
  \code
  Handle(NCollection_IncAllocator) anIncAlloc = new NCollection_IncAllocator();
  NCollection_StdAllocator<TopoDS_Shape> aSAlloc (anIncAlloc);
  std::list<TopoDS_Shape, NCollection_StdAllocator<TopoDS_Shape> > aL (aSAlloc);
  TopoDS_Solid aSolid = BRepPrimAPI_MakeBox (10., 20., 30.);
  aL.push_back (aSolid);
  \endcode
*/
template<typename T>
class NCollection_StdAllocator {
public:
  typedef T value_type;
  typedef value_type* pointer;
  typedef const value_type* const_pointer;
  typedef value_type& reference;
  typedef const value_type& const_reference;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;
  template<typename U> struct rebind {
    typedef NCollection_StdAllocator<U> other;
  };

  //! Constructor.
  /*! Creates an object using default Open CASCADE allocation mechanism, i.e. which uses
    Standard::Allocate() and Standard::Free() underneath.
  */
  NCollection_StdAllocator() throw()
  { myAlloc = NCollection_BaseAllocator::CommonBaseAllocator(); }

  //! Constructor.
  /*! Saves \a theAlloc as an underlying allocator instance.*/
  NCollection_StdAllocator( const Handle(NCollection_BaseAllocator)& theAlloc) throw()
  { myAlloc = theAlloc; }

  //! Copy constructor.
  /*! Copies Allocator() from \a Y.*/
  template<typename U> NCollection_StdAllocator( const NCollection_StdAllocator<U>& Y) throw()
  { myAlloc = Y.Allocator(); }

  //! Assignment operator
  template<typename U> NCollection_StdAllocator& operator= (const NCollection_StdAllocator<U>& Y) throw()
  { myAlloc = Y.Allocator(); return *this; }

  //! Returns an object address.
  /*! Returns &x.*/
  pointer address( reference x ) const { return &x; }

  //! Returns an object address.
  /*! Returns &x.*/
  const_pointer address( const_reference x ) const { return &x; }
  
  //! Allocates memory for \a n objects.
  /*! Uses underlying allocator to allocate memory.*/
  pointer allocate( size_type n, const void* /*hint*/ = 0 )
  { return pointer( myAlloc->Allocate( n * sizeof( value_type ))); }

  //! Frees previously allocated memory.
  /*! Uses underlying allocator to deallocate memory.*/
  void deallocate( pointer p, size_type ) { myAlloc->Free( p ); }

  //! Returns the largest value for which method allocate might succeed.
  size_type max_size() const throw()
  {
    size_type aMax = static_cast<size_type>( -1 ) / sizeof( value_type );
    return aMax;
  }

  //! Constructs an object.
  /*! Uses placement new operator and copy constructor to construct an object.*/
  void construct( pointer p, const_reference val )
  { new( static_cast<void*>( p )) value_type( val ); }

  //! Destroys the object.
  /*! Uses object destructor.*/
  void destroy( pointer p ) { p->~value_type(); }

  //! Returns an underlying NCollection_BaseAllocator instance.
  /*! Returns an object specified in the constructor.*/
  const Handle(NCollection_BaseAllocator)& Allocator() const { return myAlloc; }

protected:
  Handle(NCollection_BaseAllocator) myAlloc;
};

#if _MSC_VER
  #pragma warning (pop)
#endif


//! Implements specialization NCollection_StdAllocator<void>.
/*! Specialization is of low value and should normally be avoided in favor of a typed specialization.

  Example of use:
  \code
  Handle(NCollection_IncAllocator) anIncAlloc = new NCollection_IncAllocator();
  NCollection_StdAllocator<void> aVAlloc (anIncAlloc);
  std::vector<double, NCollection_StdAllocator<double> > aV3 (aVAlloc);
  aV3.push_back (10.);
  \endcode
*/
template<> 
class NCollection_StdAllocator<void> {
public:
  typedef void* pointer;
  typedef const void* const_pointer;
  typedef void value_type;
  template<typename U> struct rebind {
    typedef NCollection_StdAllocator<U> other;
  };

  //! Constructor.
  /*! Creates an object using default Open CASCADE allocation mechanism, i.e. which uses
    Standard::Allocate() and Standard::Free() underneath.
  */
  NCollection_StdAllocator() throw()
  { myAlloc = NCollection_BaseAllocator::CommonBaseAllocator(); }

  //! Constructor.
  /*! Saves \a theAlloc as an underlying allocator instance.*/
  NCollection_StdAllocator( const Handle(NCollection_BaseAllocator)& theAlloc) throw()
  { myAlloc = theAlloc; }

  //! Constructor.
  /*! Copies Allocator() from \a X.*/
  NCollection_StdAllocator( const NCollection_StdAllocator& X) throw() { myAlloc = X.myAlloc; }

  //! Returns an underlying NCollection_BaseAllocator instance.
  /*! Returns an object specified in the constructor.*/
  const Handle(NCollection_BaseAllocator)& Allocator() const { return myAlloc; }

  //! Assignment operator
  NCollection_StdAllocator& operator=(const NCollection_StdAllocator& X) throw()
  {
    myAlloc = X.myAlloc;
    return *this;
  }

protected:
  Handle(NCollection_BaseAllocator) myAlloc;
};

template<typename T, typename U>
inline bool operator==( const NCollection_StdAllocator<T>& X, const NCollection_StdAllocator<U>& Y)
{ return !!(X.Allocator() == Y.Allocator()); }

template<typename T, typename U>
inline bool operator!=( const NCollection_StdAllocator<T>& X, const NCollection_StdAllocator<U>& Y)
{ return !(X == Y); }


#endif