wxWidgets/include/wx/meta/movable.h
2008-01-29 11:26:30 +00:00

86 lines
2.7 KiB
C++

/////////////////////////////////////////////////////////////////////////////
// Name: wx/meta/movable.h
// Purpose: Test if a type is movable using memmove() etc.
// Author: Vaclav Slavik
// Created: 2008-01-21
// RCS-ID: $Id$
// Copyright: (c) 2008 Vaclav Slavik
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
#ifndef _WX_META_MOVABLE_H_
#define _WX_META_MOVABLE_H_
#include "wx/defs.h"
#include "wx/string.h" // for wxIsMovable<wxString> specialization
// Helper to decide if an object of type T is "movable", i.e. if it can be
// copied to another memory location using memmove() or realloc() C functions.
// C++ only gurantees that POD types (including primitive types) are
// movable.
template<typename T>
struct wxIsMovable
{
// NB: enum, because VC6 can't handle "static const bool value = true;"
enum { value = false };
};
// Macro to add wxIsMovable<T> specialization for given type that marks it
// as movable:
#define WX_DECLARE_TYPE_MOVABLE(type) \
template<> struct wxIsMovable<type> \
{ \
enum { value = true }; \
};
WX_DECLARE_TYPE_MOVABLE(bool)
WX_DECLARE_TYPE_MOVABLE(unsigned char)
WX_DECLARE_TYPE_MOVABLE(signed char)
WX_DECLARE_TYPE_MOVABLE(unsigned int)
WX_DECLARE_TYPE_MOVABLE(signed int)
WX_DECLARE_TYPE_MOVABLE(unsigned short int)
WX_DECLARE_TYPE_MOVABLE(signed short int)
WX_DECLARE_TYPE_MOVABLE(signed long int)
WX_DECLARE_TYPE_MOVABLE(unsigned long int)
WX_DECLARE_TYPE_MOVABLE(float)
WX_DECLARE_TYPE_MOVABLE(double)
WX_DECLARE_TYPE_MOVABLE(long double)
#if wxWCHAR_T_IS_REAL_TYPE
WX_DECLARE_TYPE_MOVABLE(wchar_t)
#endif
#ifdef wxLongLong_t
WX_DECLARE_TYPE_MOVABLE(wxLongLong_t)
WX_DECLARE_TYPE_MOVABLE(wxULongLong_t)
#endif
// Visual C++ 6.0 can't compile partial template specializations and as this is
// only an optimization, we can live with pointers not being recognized as
// movable types under VC6
#ifndef __VISUALC6__
// pointers are movable:
template<typename T>
struct wxIsMovable<T*>
{
enum { value = true };
};
template<typename T>
struct wxIsMovable<const T*>
{
enum { value = true };
};
#endif // !__VISUALC6__
// Our implementation of wxString is written in such way that it's safe to move
// it around. OTOH, we don't know anything about std::string.
// (NB: we don't put this into string.h and choose to include wx/string.h from
// here instead so that rarely-used wxIsMovable<T> code isn't included by
// everything)
#if !wxUSE_STL
WX_DECLARE_TYPE_MOVABLE(wxString)
#endif
#endif // _WX_META_MOVABLE_H_