TypeTraits.h

/*
 * Copyright (C) 2005 Marc Boris Duerner
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * As a special exception, you may use this file as part of a free
 * software library without restriction. Specifically, if other files
 * instantiate templates or use macros or inline functions from this
 * file, or you compile this file and link it with other files to
 * produce an executable, this file does not by itself cause the
 * resulting executable to be covered by the GNU General Public
 * License. This exception does not however invalidate any other
 * reasons why the executable file might be covered by the GNU Library
 * General Public License.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
#ifndef Pt_TypeTraits_h
#define Pt_TypeTraits_h
 
#include <Pt/Api.h>
#include <cstddef>
 
namespace Pt {
 
template <typename T, T V>
struct IntegralConstant
{
    static const T value = V;
    typedef T ValueType;
    typedef IntegralConstant<T, V> Type;
 
    operator ValueType() const
    { return value; }
};
 
 
template <bool V>
using BoolConstant = IntegralConstant<bool, V>;
 
typedef BoolConstant<false> FalseType;
typedef BoolConstant<true> TrueType;
 
 
template<class T, class U>
struct IsSame : FalseType 
{};
 
 
template<class T>
struct IsSame<T, T> : TrueType 
{};
 
 
template <bool Condition, typename TrueT, typename FalseT>
struct IfElse
{
    typedef TrueT Type;
};
 
 
template <typename TrueT, typename FalseT>
struct IfElse<false, TrueT, FalseT>
{
    typedef FalseT Type;
};
 
 
template <typename T>
struct TypeTraitsBase 
{
    typedef T Value;
    typedef const T ConstValue;
    typedef T& Reference;
    typedef const T& ConstReference;
    typedef T* Pointer;
    typedef const T* ConstPointer;
};
 
template <typename T>
struct TypeTraits : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 0;
    static const unsigned int isPointer = 0;
    static const unsigned int isReference = 0;
};
 
template <typename T>
struct TypeTraits<const T> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 1;
    static const unsigned int isPointer = 0;
    static const unsigned int isReference = 0;
};
 
 
template <typename T>
struct TypeTraits<T&> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 0;
    static const unsigned int isPointer = 0;
    static const unsigned int isReference = 1;
};
 
 
template <typename T>
struct TypeTraits<const T&> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 1;
    static const unsigned int isPointer = 0;
    static const unsigned int isReference = 1;
};
 
 
template <typename T>
struct TypeTraits<T*> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 0;
    static const unsigned int isPointer = 1;
    static const unsigned int isReference = 0;
};
 
 
template <typename T>
struct TypeTraits<const T*> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 1;
    static const unsigned int isPointer = 1;
    static const unsigned int isReference = 0;
};
 
 
template <typename T, std::size_t N>
struct TypeTraits<T[N]> : public TypeTraitsBase<T>
{
    static const unsigned int isConst = 0;
    static const unsigned int isPointer = 1;
    static const unsigned int isReference = 0;
};
 
 
template <>
struct TypeTraits<void>
{
    typedef void Value;
    typedef void ConstType;
    typedef void Reference;
    typedef void ConstReference;
    typedef void* Pointer;
    typedef void* ConstPointer;
 
    static const unsigned int isConst = 0;
    static const unsigned int isPointer = 0;
    static const unsigned int isReference = 0;
};
 
 
template <typename Base, typename Derived>
class IsCompatibleImpl
{
    private:
        struct YesType
        {
            char value;
        };
 
        struct NoType
        {
            char value[2];
        };
 
        typedef typename TypeTraits<Base>::Value BaseType;
        typedef typename TypeTraits<Derived>::Value DerivedType;
 
        static YesType test(BaseType*);
        static NoType test(...);
 
    public:
        enum
        {
            value = sizeof(test(static_cast<DerivedType*>(0))) == sizeof(YesType)
        };
};
 
 
template <typename Base, typename Derived>
class IsCompatible
: public BoolConstant< IsCompatibleImpl<Base, Derived>::value >
{};
 
 
template <typename T>
struct IntTraits
{};
    
template <>
struct IntTraits<signed char>
{
    typedef unsigned char Unsigned;
    typedef signed char Signed;
 
    static const unsigned int isSigned = 1;
};
 
template <>
struct IntTraits<unsigned char>
{
    typedef unsigned char Unsigned;
    typedef signed char Signed;
 
    static const unsigned int isSigned = 0;
};
 
template <>
struct IntTraits<short>
{
    typedef unsigned short Unsigned;
    typedef signed short Signed;
 
    static const unsigned int isSigned = 1;
};
 
template <>
struct IntTraits<unsigned short>
{
    typedef unsigned short Unsigned;
    typedef signed short Signed;
 
    static const unsigned int isSigned = 0;
};
 
template <>
struct IntTraits<int>
{
    typedef unsigned int Unsigned;
    typedef signed int Signed;
 
    static const unsigned int isSigned = 1;
};
 
template <>
struct IntTraits<unsigned int>
{
    typedef unsigned int Unsigned;
    typedef signed int Signed;
 
    static const unsigned int isSigned = 0;
};
 
template <>
struct IntTraits<long>
{
    typedef unsigned long Unsigned;
    typedef signed long Signed;
 
    static const unsigned int isSigned = 1;
};
 
template <>
struct IntTraits<unsigned long>
{
    typedef unsigned long Unsigned;
    typedef signed long Signed;
 
    static const unsigned int isSigned = 0;
};
 
template <>
struct IntTraits<long long>
{
    typedef unsigned long long Unsigned;
    typedef signed long long Signed;
 
    static const unsigned int isSigned = 1;
};
 
template <>
struct IntTraits<unsigned long long>
{
    typedef unsigned long long Unsigned;
    typedef signed long long Signed;
 
    static const unsigned int isSigned = 0;
};
 
} // namespace Pt
 
#endif // Pt_TypeTraits_h