Logo Search packages:      
Sourcecode: poco version File versions  Download package

Any.h
//
// Any.h
//
// $Id: //poco/1.3/Foundation/include/Poco/Any.h#2 $
//
// Library: Foundation
// Package: Core
// Module:  Any
//
// Copyright Kevlin Henney, 2000, 2001, 2002. All rights reserved.
// Extracted from Boost 1.33.1 lib and adapted for poco: Peter Schojer/AppliedInformatics 2006-02-02
//
// 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.
//


#ifndef Foundation_Any_INCLUDED
#define Foundation_Any_INCLUDED


#include "Poco/Exception.h"
#include <algorithm>
#include <typeinfo>


namespace Poco {


00049 class Any
      /// An Any class represents a general type and is capable of storing any type, supporting type-safe extraction
      /// of the internally stored data.
      ///
      /// Code taken from the Boost 1.33.1 library. Original copyright by Kevlin Henney. Modified for Poco
      /// by Applied Informatics.
{
public:
    Any():
            _content(0)
            /// Creates an empty any type.
    {
    }

    template <typename ValueType>
00064     Any(const ValueType& value):
            _content(new Holder<ValueType>(value))
            /// Creates an any which stores the init parameter inside.
            ///
            /// Example: 
            ///     Any a(13); 
            ///     Any a(string("12345"));
    {
    }

    Any(const Any& other):
            _content(other._content ? other._content->clone() : 0)
            /// Copy constructor, works with empty Anys and initialized Any values.
    {
    }

    ~Any()
    {
        delete _content;
    }

00085     Any& swap(Any& rhs)
            /// Swaps the content of the two Anys.
    {
        std::swap(_content, rhs._content);
        return *this;
    }

    template <typename ValueType>
00093     Any& operator = (const ValueType& rhs)
            /// Assignment operator for all types != Any.
            ///
            /// Example: 
            ///    Any a = 13; 
            ///    Any a = string("12345");
    {
        Any(rhs).swap(*this);
        return *this;
    }

00104     Any& operator = (const Any& rhs)
            /// Assignment operator for Any.
    {
        Any(rhs).swap(*this);
        return *this;
    }

00111     bool empty() const
            /// returns true if the Any is empty
    {
        return !_content;
    }

00117     const std::type_info& type() const
            /// Returns the type information of the stored content.
            /// If the Any is empty typeid(void) is returned.
            /// It is suggested to always query an Any for its type info before trying to extract
            /// data via an AnyCast/RefAnyCast.
    {
        return _content ? _content->type() : typeid(void);
    }

private:
00127     class Placeholder
    {
    public:
        virtual ~Placeholder()
        {
        }

        virtual const std::type_info& type() const = 0;
        virtual Placeholder* clone() const = 0;
    };

    template <typename ValueType>
00139     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:
    template <typename ValueType>
    friend ValueType* AnyCast(Any*);

    template <typename ValueType>
    friend ValueType* UnsafeAnyCast(Any*);

    Placeholder* _content;
};


template <typename ValueType>
00172 ValueType* AnyCast(Any* operand)
      /// AnyCast operator used to extract the ValueType from an Any*. Will return a pointer
      /// to the stored value. 
      ///
      /// Example Usage: 
      ///     MyType* pTmp = AnyCast<MyType*>(pAny).
      /// Will return NULL if the cast fails, i.e. types don't match.
{
    return operand && operand->type() == typeid(ValueType)
                ? &static_cast<Any::Holder<ValueType>*>(operand->_content)->_held
                : 0;
}


template <typename ValueType>
const ValueType* AnyCast(const Any* operand)
      /// AnyCast operator used to extract a const ValueType pointer from an const Any*. Will return a const pointer
      /// to the stored value. 
      ///
      /// Example Usage:
      ///     const MyType* pTmp = AnyCast<MyType*>(pAny).
      /// Will return NULL if the cast fails, i.e. types don't match.
{
    return AnyCast<ValueType>(const_cast<Any*>(operand));
}


template <typename ValueType>
ValueType AnyCast(const Any& operand)
      /// AnyCast operator used to extract a copy of the ValueType from an const Any&.
      ///
      /// Example Usage: 
      ///     MyType tmp = AnyCast<MyType>(anAny).
      /// Will throw a BadCastException if the cast fails.
      /// Dont use an AnyCast in combination with references, i.e. MyType& tmp = ... or const MyType& = ...
      /// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
      /// these cases.
{
    ValueType* result = AnyCast<ValueType>(const_cast<Any*>(&operand));
    if (!result) throw BadCastException("Failed to convert between const Any types");
    return *result;
}


template <typename ValueType>
ValueType AnyCast(Any& operand)
      /// AnyCast operator used to extract a copy of the ValueType from an Any&.
      ///
      /// Example Usage: 
      ///     MyType tmp = AnyCast<MyType>(anAny).
      /// Will throw a BadCastException if the cast fails.
      /// Dont use an AnyCast in combination with references, i.e. MyType& tmp = ... or const MyType& tmp = ...
      /// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
      /// these cases.
{
    ValueType* result = AnyCast<ValueType>(&operand);
    if (!result) throw BadCastException("Failed to convert between Any types");
    return *result;
}


template <typename ValueType>
const ValueType& RefAnyCast(const Any & operand)
      /// AnyCast operator used to return a const reference to the internal data. 
      ///
      /// Example Usage: 
      ///     const MyType& tmp = RefAnyCast<MyType>(anAny);
{
    ValueType* result = AnyCast<ValueType>(const_cast<Any*>(&operand));
    if (!result) throw BadCastException("RefAnyCast: Failed to convert between const Any types");
    return *result;
}


template <typename ValueType>
ValueType& RefAnyCast(Any& operand)
      /// AnyCast operator used to return a reference to the internal data.
      ///
      /// Example Usage: 
      ///     MyType& tmp = RefAnyCast<MyType>(anAny);
{
    ValueType* result = AnyCast<ValueType>(&operand);
    if (!result) throw BadCastException("RefAnyCast: Failed to convert between Any types");
    return *result;
}


template <typename ValueType>
00260 ValueType* UnsafeAnyCast(Any* operand)
      /// The "unsafe" versions of AnyCast are not part of the
      /// public interface and may be removed at any time. They are
      /// required where we know what type is stored in the any and can't
      /// use typeid() comparison, e.g., when our types may travel across
      /// different shared libraries.
{
    return &static_cast<Any::Holder<ValueType>*>(operand->_content)->_held;
}


template <typename ValueType>
const ValueType* UnsafeAnyCast(const Any* operand)
      /// The "unsafe" versions of AnyCast are not part of the
      /// public interface and may be removed at any time. They are
      /// required where we know what type is stored in the any and can't
      /// use typeid() comparison, e.g., when our types may travel across
      /// different shared libraries.
{
    return AnyCast<ValueType>(const_cast<Any*>(operand));
}


} // namespace Poco


#endif

Generated by  Doxygen 1.6.0   Back to index