+++ /dev/null
-/* ========================================================================
-** Extended Template and Library
-** Abstraction for a Generic Value Type
-** $Id$
-**
-** Copyright (c) 2002 Adrian Bentley
-**
-** This package is free software; you can redistribute it and/or
-** modify it under the terms of the GNU General Public License as
-** published by the Free Software Foundation; either version 2 of
-** the License, or (at your option) any later version.
-**
-** This package 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
-** General Public License for more details.
-**
-** === N O T E S ===========================================================
-**
-** This is an internal header file, included by other ETL headers.
-** You should not attempt to use it directly.
-**
-** ========================================================================= */
-
-/* === S T A R T =========================================================== */
-
-#ifndef __ETL__VALUE_H
-#define __ETL__VALUE_H
-
-/* === H E A D E R S ======================================================= */
-#include <algorithm>
-#include <typeinfo>
-#include <cassert>
-
-/* === M A C R O S ========================================================= */
-
-/* === T Y P E D E F S ===================================================== */
-
-/* === C L A S S E S & S T R U C T S ======================================= */
-
-/*! \note This class may be specialized to support binary compatibility
- for desired objects (e.g. point3,vector3,float[3]).
- However it MUST be declared within scope that you are using the
- values....
-
- \warning If you specialize this class for something that isn't binary
- compatible, then your values could easily report belonging to
- the wrong types.
-*/
-template < typename T >
-class value_store_type
-{
-public:
- typedef T value_type;
-};
-
-_ETL_BEGIN_NAMESPACE
-
-/*! \class value _value.h ETL/value
- \brief Abstraction of the concept of a generic value
-
- Modified from ideas for the boost::any type. Added binary compatibility
- structure
-*/
-class value
-{
- struct contentholder
- {
- virtual ~contentholder() {}
- virtual contentholder *clone() const = 0;
- virtual const std::type_info &type() const = 0;
- };
-
- contentholder *content;
-
-public: //constructor interface
- value()
- :content(0)
- {
- }
-
- value(const value &v)
- :content( v.content ? v.content->clone() : 0 )
- {
- }
-
- /* Copies the object passed to it
- */
- template < typename T >
- value(const T &v)
- :content( new holder< typename value_store_type<T>::value_type >
- (reinterpret_cast<const typename value_store_type<T>::value_type &>(v)) )
- {
- }
-
-public: //modifier interface
-
- value & swap(value & rhs)
- {
- std::swap(content, rhs.content);
- return *this;
- }
-
- template<typename ValueType>
- value & operator=(const ValueType & rhs)
- {
- value(rhs).swap(*this);
- return *this;
- }
-
- value & operator=(const value & rhs)
- {
- value(rhs).swap(*this);
- return *this;
- }
-
-public: //query interface
-
- bool empty() const
- {
- return content == 0;
- }
-
- const std::type_info & type() const
- {
- return content ? content->type() : typeid(void);
- }
-
-private: //implementation interface
-
- template < typename T >
- class holder : public contentholder
- {
- public: //representation
- T obj;
-
- public: //constructor interface
-
- holder(const T &o)
- :obj(o)
- {
- }
-
- holder(const holder<T> &h)
- :obj(h.obj)
- {
- }
-
- public: //accessor interface
- virtual contentholder *clone() const
- {
- return new holder(*this);
- }
-
- virtual const std::type_info &type() const
- {
- return typeid(T);
- }
-
- public: //allocation interface
- void *operator new(unsigned int size)
- {
- assert(size == sizeof(holder<T>));
-
- //use pool allocation at some point
- return malloc(size);
- }
-
- void operator delete(void *p)
- {
- assert(p);
- //use pool allocation at some point
- return free(p);
- }
- };
-
- template < typename ValueType >
- friend ValueType *value_cast(value *v);
-};
-
-/*! Is thrown for bad value_casts (when using a reference...)
-*/
-class bad_value_cast : public std::bad_cast
-{
-public:
- virtual const char * what() const throw()
- {
- return "etl::bad_value_cast: " "failed conversion using boost::value_cast";
- }
-};
-
-/*! Returns a pointer to the desired value type if the value_type and the internal
- binary format agree (mediated by using the value_store_type class), otherwise
- it returns 0.
-
- \see value_store_type
-*/
-template < typename ValueType >
-ValueType *value_cast(value *v)
-{
- assert(v);
-
- return ( typeid(typename value_store_type<ValueType>::value_type) == v->type() )
- ? &static_cast<value::holder<ValueType> *>(v->content)->obj
- : 0;
-}
-
-/*! Same as above except tweaked to allow const cast (possibly for purposes involving
- type agreement... if const impacts a typeid call I do not know...)
-*/
-template < typename ValueType >
-const ValueType * value_cast(const value *v)
-{
- return value_cast<ValueType>(const_cast<value *>(v));
-}
-
-/*! Extract a copy of the internal object and will throw a bad_value_cast exception
- if the types do not agree.
-
- \note I'm not sure why boost::any didn't use a reference here... there must be a reason...
-
- \see bad_value_cast
-*/
-template < typename ValueType >
-ValueType value_cast(const value &v)
-{
- const ValueType * result = value_cast<ValueType>(&v);
- if(!result)
- throw bad_value_cast();
- return *result;
-}
-
-_ETL_END_NAMESPACE
-
-/* === E N D =============================================================== */
-
-#endif
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