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287 lines
8.2 KiB
C++
287 lines
8.2 KiB
C++
//
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// Any.h
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//
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// $Id: //poco/Main/Foundation/include/Poco/Any.h#3 $
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//
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// Library: Foundation
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// Package: Core
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// Module: Any
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//
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// Copyright Kevlin Henney, 2000, 2001, 2002. All rights reserved.
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// Extracted from Boost 1.33.1 lib and adapted for poco: Peter Schojer/AppliedInformatics 2006-02-02
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//
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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_Any_INCLUDED
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#define Foundation_Any_INCLUDED
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#include "Poco/Exception.h"
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#include <algorithm>
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#include <typeinfo>
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namespace Poco {
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class Any
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/// An Any class represents a general type and is capable of storing any type, supporting type-safe extraction
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/// of the internally stored data.
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///
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/// Code taken from the Boost 1.33.1 library. Original copyright by Kevlin Henney. Modified for Poco
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/// by Applied Informatics.
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{
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public:
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Any():
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_content(0)
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/// Creates an empty any type.
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{
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}
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template <typename ValueType>
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Any(const ValueType& value):
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_content(new Holder<ValueType>(value))
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/// Creates an any which stores the init parameter inside.
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///
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/// Example:
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/// Any a(13);
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/// Any a(string("12345"));
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{
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}
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Any(const Any& other):
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_content(other._content ? other._content->clone() : 0)
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/// Copy constructor, works with empty Anys and initialized Any values.
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{
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}
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~Any()
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{
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delete _content;
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}
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Any& swap(Any& rhs)
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/// Swaps the content of the two Anys.
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{
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std::swap(_content, rhs._content);
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return *this;
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}
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template <typename ValueType>
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Any& operator = (const ValueType& rhs)
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/// Assignment operator for all types != Any.
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///
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/// Example:
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/// Any a = 13;
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/// Any a = string("12345");
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{
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Any(rhs).swap(*this);
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return *this;
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}
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Any& operator = (const Any& rhs)
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/// Assignment operator for Any.
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{
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Any(rhs).swap(*this);
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return *this;
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}
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bool empty() const
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/// returns true if the Any is empty
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{
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return !_content;
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}
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const std::type_info& type() const
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/// Returns the type information of the stored content.
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/// If the Any is empty typeid(void) is returned.
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/// It is suggested to always query an Any for its type info before trying to extract
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/// data via an AnyCast/RefAnyCast.
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{
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return _content ? _content->type() : typeid(void);
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}
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private:
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class Placeholder
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{
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public:
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virtual ~Placeholder()
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{
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}
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virtual const std::type_info& type() const = 0;
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virtual Placeholder* clone() const = 0;
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};
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template <typename ValueType>
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class Holder: public Placeholder
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{
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public:
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Holder(const ValueType& value):
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_held(value)
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{
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}
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virtual const std::type_info& type() const
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{
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return typeid(ValueType);
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}
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virtual Placeholder* clone() const
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{
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return new Holder(_held);
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}
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ValueType _held;
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};
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private:
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template <typename ValueType>
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friend ValueType* AnyCast(Any*);
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template <typename ValueType>
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friend ValueType* UnsafeAnyCast(Any*);
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Placeholder* _content;
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};
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template <typename ValueType>
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ValueType* AnyCast(Any* operand)
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/// AnyCast operator used to extract the ValueType from an Any*. Will return a pointer
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/// to the stored value.
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///
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/// Example Usage:
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/// MyType* pTmp = AnyCast<MyType*>(pAny).
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/// Will return NULL if the cast fails, i.e. types don't match.
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{
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return operand && operand->type() == typeid(ValueType)
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? &static_cast<Any::Holder<ValueType>*>(operand->_content)->_held
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: 0;
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}
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template <typename ValueType>
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const ValueType* AnyCast(const Any* operand)
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/// AnyCast operator used to extract a const ValueType pointer from an const Any*. Will return a const pointer
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/// to the stored value.
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///
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/// Example Usage:
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/// const MyType* pTmp = AnyCast<MyType*>(pAny).
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/// Will return NULL if the cast fails, i.e. types don't match.
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{
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return AnyCast<ValueType>(const_cast<Any*>(operand));
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}
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template <typename ValueType>
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ValueType AnyCast(const Any& operand)
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/// AnyCast operator used to extract a copy of the ValueType from an const Any&.
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///
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/// Example Usage:
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/// MyType tmp = AnyCast<MyType>(anAny).
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/// Will throw a BadCastException if the cast fails.
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/// Dont use an AnyCast in combination with references, i.e. MyType& tmp = ... or const MyType& = ...
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/// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
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/// these cases.
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{
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ValueType* result = AnyCast<ValueType>(const_cast<Any*>(&operand));
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if (!result) throw BadCastException("Failed to convert between const Any types");
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return *result;
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}
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template <typename ValueType>
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ValueType AnyCast(Any& operand)
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/// AnyCast operator used to extract a copy of the ValueType from an Any&.
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///
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/// Example Usage:
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/// MyType tmp = AnyCast<MyType>(anAny).
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/// Will throw a BadCastException if the cast fails.
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/// Dont use an AnyCast in combination with references, i.e. MyType& tmp = ... or const MyType& tmp = ...
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/// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
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/// these cases.
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{
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ValueType* result = AnyCast<ValueType>(&operand);
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if (!result) throw BadCastException("Failed to convert between Any types");
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return *result;
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}
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template <typename ValueType>
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const ValueType& RefAnyCast(const Any & operand)
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/// AnyCast operator used to return a const reference to the internal data.
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///
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/// Example Usage:
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/// const MyType& tmp = RefAnyCast<MyType>(anAny);
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{
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ValueType* result = AnyCast<ValueType>(const_cast<Any*>(&operand));
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if (!result) throw BadCastException("RefAnyCast: Failed to convert between const Any types");
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return *result;
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}
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template <typename ValueType>
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ValueType& RefAnyCast(Any& operand)
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/// AnyCast operator used to return a reference to the internal data.
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///
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/// Example Usage:
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/// MyType& tmp = RefAnyCast<MyType>(anAny);
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{
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ValueType* result = AnyCast<ValueType>(&operand);
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if (!result) throw BadCastException("RefAnyCast: Failed to convert between Any types");
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return *result;
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}
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template <typename ValueType>
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ValueType* UnsafeAnyCast(Any* operand)
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/// The "unsafe" versions of AnyCast are not part of the
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/// public interface and may be removed at any time. They are
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/// required where we know what type is stored in the any and can't
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/// use typeid() comparison, e.g., when our types may travel across
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/// different shared libraries.
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{
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return &static_cast<Any::Holder<ValueType>*>(operand->_content)->_held;
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}
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template <typename ValueType>
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const ValueType* UnsafeAnyCast(const Any* operand)
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/// The "unsafe" versions of AnyCast are not part of the
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/// public interface and may be removed at any time. They are
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/// required where we know what type is stored in the any and can't
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/// use typeid() comparison, e.g., when our types may travel across
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/// different shared libraries.
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{
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return AnyCast<ValueType>(const_cast<Any*>(operand));
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}
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} // namespace Poco
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#endif
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