extraction.h.svn-base

很好用的网络封装库,不熟悉网络编程的人也可以使用。使用风格良好的标准c++编写。

//
// Extraction.h
//
// $Id: //poco/1.3/Data/include/Poco/Data/Extraction.h#2 $
//
// Library: Data
// Package: DataCore
// Module:  Extraction
//
// Definition of the Extraction class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// 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 Data_Extraction_INCLUDED
#define Data_Extraction_INCLUDED


#include "Poco/Data/Data.h"
#include "Poco/Data/AbstractExtraction.h"
#include "Poco/Data/Prepare.h"
#include "Poco/Data/TypeHandler.h"
#include "Poco/Data/Column.h"
#include "Poco/Data/DataException.h"
#include <set>
#include <vector>
#include <list>
#include <map>
#include <cstddef>


namespace Poco {
namespace Data {


template <class T>
class Extraction: public AbstractExtraction
	/// Concrete Data Type specific extraction of values from a query result set.
{
public:
	Extraction(T& result): _rResult(result), _default(), _extracted(false)
		/// Creates an Extraction object, uses an empty object T as default value
	{
	}

	Extraction(T& result, const T& def): _rResult(result), _default(def), _extracted(false)
		/// Creates an Extraction object, uses the provided def object as default value
	{
	}

	~Extraction()
		/// Destroys the Extraction object.
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<T>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return 1u;
	}

	std::size_t numOfRowsAllowed() const
	{
		return 1u;
	}

	void extract(std::size_t pos)
	{
		if (_extracted) throw ExtractException("value already extracted");
		_extracted = true;
		TypeHandler<T>::extract(pos, _rResult, _default, getExtractor());
	}

	void reset()
	{
		_extracted = false;
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<T>(pPrep, pos, _default);
	}

private:
	T&   _rResult;
	T    _default;   // copy the default
	bool _extracted;
};


template <class T>
class Extraction<std::vector<T> >: public AbstractExtraction
	/// Vector Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::vector<T>& result): _rResult(result), _default()
	{
	}

	Extraction(std::vector<T>& result, const T& def): _rResult(result), _default(def)
	{
	}

	virtual ~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<T>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		_rResult.push_back(_default);
		TypeHandler<T>::extract(pos, _rResult.back(), _default, getExtractor());
	}

	virtual void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<T>(pPrep, pos, _default);
	}

protected:

	const std::vector<T>& result() const
	{
		return _rResult;
	}

private:
	std::vector<T>& _rResult;
	T               _default; // copy the default
};


template <class T>
class Extraction<std::list<T> >: public AbstractExtraction
	/// List Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::list<T>& result): _rResult(result), _default()
	{
	}

	Extraction(std::list<T>& result, const T& def): _rResult(result), _default(def)
	{
	}

	virtual ~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<T>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		_rResult.push_back(_default);
		TypeHandler<T>::extract(pos, _rResult.back(), _default, getExtractor());
	}

	virtual void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<T>(pPrep, pos, _default);
	}

protected:

	const std::list<T>& result() const
	{
		return _rResult;
	}

private:
	std::list<T>& _rResult;
	T               _default; // copy the default
};


template <class T, class C = std::vector<T> >
class InternalExtraction: public Extraction<C>
	/// Container Data Type specialization extension for extraction of values from a query result set.
	///
	/// This class is intended for PocoData internal use - it is used by StatementImpl 
	/// to automaticaly create internal Extraction in cases when statement returns data and no external storage
	/// was supplied. It is later used by RecordSet to retrieve the fetched data after statement execution.
	/// It takes ownership of the Column pointer supplied as constructor argument. Column object, in turn
	/// owns the data vector pointer.
	///
	/// InternalExtraction objects can not be copied or assigned.
{
public:
	explicit InternalExtraction(C& result, Column<T>* pColumn): 
		Extraction<C>(result), 
		_pColumn(pColumn)
		/// Creates InternalExtraction.
		
	{
	}

	~InternalExtraction()
		/// Destroys InternalExtraction.
	{
		delete _pColumn;
	}

	void reset()
	{
		_pColumn->reset();
	}	

	const T& value(int index) const
	{
		try
		{ 
			return Extraction<C>::result().at(index); 
		}
		catch (std::out_of_range& ex)
		{ 
			throw RangeException(ex.what()); 
		}
	}

	const Column<T>& column() const
	{
		return *_pColumn;
	}

private:
	InternalExtraction();
	InternalExtraction(const InternalExtraction&);
	InternalExtraction& operator = (const InternalExtraction&);

	Column<T>* _pColumn;
};


template <class T>
class Extraction<std::set<T> >: public AbstractExtraction
	/// Set Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::set<T>& result): _rResult(result), _default()
	{
	}

	Extraction(std::set<T>& result, const T& def): _rResult(result), _default(def)
	{
	}

	~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<T>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		T tmp;
		TypeHandler<T>::extract(pos, tmp, _default, getExtractor());
		_rResult.insert(tmp);
	}

	void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<T>(pPrep, pos, _default);
	}

private:
	std::set<T>& _rResult;
	T            _default; // copy the default
};


template <class T>
class Extraction<std::multiset<T> >: public AbstractExtraction
	/// Multiset Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::multiset<T>& result): _rResult(result), _default()
	{
	}

	Extraction(std::multiset<T>& result, const T& def): _rResult(result), _default(def)
	{
	}

	~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<T>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		T tmp;
		TypeHandler<T>::extract(pos, tmp, _default, getExtractor());
		_rResult.insert(tmp);
	}

	void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<T>(pPrep, pos, _default);
	}

private:
	std::multiset<T>& _rResult;
	T                 _default; // copy the default
};


template <class K, class V>
class Extraction<std::map<K, V> >: public AbstractExtraction
	/// Map Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::map<K, V>& result): _rResult(result), _default()
	{
	}

	Extraction(std::map<K, V>& result, const V& def): _rResult(result), _default(def)
	{
	}

	~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<V>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		V tmp;
		TypeHandler<V>::extract(pos, tmp, _default, getExtractor());
		_rResult.insert(std::make_pair(tmp(), tmp));
	}

	void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<V>(pPrep, pos, _default);
	}


private:
	std::map<K, V>& _rResult;
	V               _default; // copy the default
};


template <class K, class V>
class Extraction<std::multimap<K, V> >: public AbstractExtraction
	/// Multimap Data Type specialization for extraction of values from a query result set.
{
public:
	Extraction(std::multimap<K, V>& result): _rResult(result), _default()
	{
	}

	Extraction(std::multimap<K, V>& result, const V& def): _rResult(result), _default(def)
	{
	}

	~Extraction()
	{
	}

	std::size_t numOfColumnsHandled() const
	{
		return TypeHandler<V>::size();
	}

	std::size_t numOfRowsHandled() const
	{
		return _rResult.size();
	}

	std::size_t numOfRowsAllowed() const
	{
		return getLimit();
	}

	void extract(std::size_t pos)
	{
		V tmp;
		TypeHandler<V>::extract(pos, tmp, _default, getExtractor());
		_rResult.insert(std::make_pair(tmp(), tmp));
	}

	void reset()
	{
	}

	AbstractPrepare* createPrepareObject(AbstractPreparation* pPrep, std::size_t pos) const
	{
		return new Prepare<V>(pPrep, pos, _default);
	}

private:
	std::multimap<K, V>& _rResult;
	V                    _default; // copy the default
};


template <typename T> Extraction<T>* into(T& t)
	/// Convenience function to allow for a more compact creation of a default extraction object
{
	return new Extraction<T>(t);
}


template <typename T> Extraction<T>* into(T& t, const T& def)
	/// Convenience function to allow for a more compact creation of an extraction object with the given default
{
	return new Extraction<T>(t, def);
}


} } // namespace Poco::Data


#endif // Data_Extraction_INCLUDED