libxml-cxx/src/xml-cxx/any.hxx

/*! @file

    @id $Id$

    taken from boost.org boost::Any
    
    */
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// 45678901234567890123456789012345678901234567890123456789012345678901234567890

// See http://www.boost.org/libs/any for Documentation.

#ifndef XML_CXX_ANY_INCLUDED
#define XML_CXX_ANY_INCLUDED

#include <algorithm>
#include <typeinfo>
#include <stdexcept>

namespace xml {

  class Any {
      
    public: // structors

      Any(): content(0) {}

      template<typename ValueType> Any(const ValueType& value):
          content(new holder<ValueType>(value)) {
      }

      Any(const Any& other): content(other.content?other.content->clone():0) {}

      ~Any() {
        delete content;
      }

    public: // modifiers

      Any& swap(Any& rhs) {
        std::swap(content, rhs.content);
        return *this;
      }

      template<typename ValueType> Any& operator=(const ValueType& rhs) {
        Any(rhs).swap(*this);
        return *this;
      }

      Any& operator=(const Any& rhs) {
        Any(rhs).swap(*this);
        return *this;
      }

    public: // queries

      bool empty() const {
        return !content;
      }

      const std::type_info& type() const {
        return content?content->type():typeid(void);
      }

    private: // types
      
      class placeholder {
        public: // structors
          virtual ~placeholder() {}
          virtual const std::type_info& type() const = 0;
          virtual placeholder* clone() const = 0;
      };

      template<typename ValueType> class holder: public placeholder {
          
        public:

          holder(const ValueType& value): held(value) {}

          virtual const std::type_info& type() const {
            return typeid(ValueType);
          }

          virtual placeholder* clone() const {
            return new holder(held);
          }

          ValueType held;

      };

    private: // representation

      template<typename ValueType> friend ValueType* any_cast(Any*);
      template<typename ValueType> friend ValueType& any_cast(Any&);

      placeholder* content;

  };

  template<typename ValueType> ValueType* any_cast(Any* operand) {
    return operand && operand->type() == typeid(ValueType)
      ? &static_cast<Any::holder<ValueType>*>(operand->content)->held
      : 0;
  }

  template<typename ValueType> const ValueType* any_cast(const Any* operand) {
    return any_cast<ValueType>(const_cast<Any*>(operand));
  }

  template<typename ValueType> ValueType& any_cast(Any& operand) {
    if (operand.type()==typeid(ValueType))
      return static_cast<Any::holder<ValueType>*>(operand.content)->held;
    throw std::bad_cast();
  }

  template<typename ValueType> const ValueType& any_cast(const Any& operand) {
    return any_cast<ValueType>(const_cast<Any&>(operand));
  }

}

// Copyright Kevlin Henney, 2000, 2001, 2002. All rights reserved.
//
// Distributed under the Boost Software License, Version 1.0. (See
// http://www.boost.org/LICENSE_1_0.txt)

// Boost Software License - Version 1.0 - August 17th, 2003

// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:

// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

#endif