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StatementImpl.h
//
// StatementImpl.h
//
// $Id: //poco/1.4/Data/include/Poco/Data/StatementImpl.h#1 $
//
// Library: Data
// Package: DataCore
// Module:  StatementImpl
//
// Definition of the StatementImpl 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_StatementImpl_INCLUDED
#define Data_StatementImpl_INCLUDED


#include "Poco/Data/Data.h"
#include "Poco/Data/AbstractBinding.h"
#include "Poco/Data/AbstractExtraction.h"
#include "Poco/Data/Range.h"
#include "Poco/Data/Column.h"
#include "Poco/Data/Extraction.h"
#include "Poco/RefCountedObject.h"
#include "Poco/AutoPtr.h"
#include "Poco/String.h"
#include "Poco/Format.h"
#include "Poco/Exception.h"
#include <vector>
#include <sstream>


namespace Poco {
namespace Data {


00062 class Data_API StatementImpl: public Poco::RefCountedObject
      /// StatementImpl interface that subclasses must implement to define database dependent query execution.
      ///
      /// StatementImpl's are noncopyable.
{
public:
      enum State
      {
            ST_INITIALIZED,
            ST_COMPILED,
            ST_BOUND,
            ST_DONE,
            ST_RESET
      };

      StatementImpl();
            /// Creates the StatementImpl.

      virtual ~StatementImpl();
            /// Destroys the StatementImpl.

00083       template <typename T> void add(const T& t)
            /// Appends SQl statement (fragments).
      {
            _ostr << t;
      }

      void addBinding(AbstractBinding* info);
            /// Registers the Binding at the StatementImpl.

      void addExtract(AbstractExtraction* info);
            /// Registers objects used for extracting data at the StatementImpl.

      void setExtractionLimit(const Limit& extrLimit);
            /// Changes the extractionLimit to extrLimit. Per default no limit (EXTRACT_UNLIMITED) is set.

      std::string toString() const;
            /// Create a string version of the SQL statement.

      Poco::UInt32 execute();
            /// Executes a statement. Returns the number of rows extracted.

      void reset();
            /// Resets the statement, so that we can reuse all bindings and re-execute again.

      State getState() const;
            /// Returns the state of the Statement.

protected:
      virtual Poco::UInt32 columnsReturned() const = 0;
            /// Returns number of columns returned by query. 

      virtual const MetaColumn& metaColumn(Poco::UInt32 pos) const = 0;
            /// Returns column meta data.

      const MetaColumn& metaColumn(const std::string& name) const;
            /// Returns column meta data.

      virtual bool hasNext() = 0;
            /// Returns true if a call to next() will return data. 
            ///
            /// Note that the implementation must support
            /// several consecutive calls to hasNext without data getting lost, 
            /// ie. hasNext(); hasNext(); next() must be equal to hasNext(); next();

      virtual void next() = 0;
            /// Retrieves the next row from the resultset.
            ///
            /// Will throw, if the resultset is empty.
            /// Expects the statement to be compiled and bound

      virtual bool canBind() const = 0;
            /// Returns if another bind is possible.

      virtual void compileImpl() = 0;
            /// Compiles the statement, doesn't bind yet.

      virtual void bindImpl() = 0;
            /// Binds parameters.

      virtual AbstractExtractor& extractor() = 0;
            /// Returns the concrete extractor used by the statement.

      const AbstractExtractionVec& extractions() const;
            /// Returns the extractions vector.

      virtual AbstractBinder& binder() = 0;
            /// Returns the concrete binder used by the statement.

      int columnsExtracted() const;
            /// Returns the number of columns that the extractors handle.

      const AbstractBindingVec& bindings() const;
            /// Returns the bindings.

      AbstractBindingVec& bindings();
            /// Returns the bindings.

      AbstractExtractionVec& extractions();
            /// Returns the extractions vector.

      void makeExtractors(Poco::UInt32 count);
            /// Creates extraction vector. Used in case when there is
            /// data returned, but no extraction supplied externally.

private:
      void compile();
            /// Compiles the statement, if not yet compiled. doesn't bind yet

      void bind();
            /// Binds the statement, if not yet bound.

      Poco::UInt32 executeWithLimit();
            /// Executes with an upper limit set.

      Poco::UInt32 executeWithoutLimit();
            /// Executes without an upper limit set.

      void fixupExtraction();
            /// Sets the AbstractExtractor at the extractors.

      void fixupBinding();
            /// Sets the AbstractBinder at the bindings

      void resetBinding();
            /// Resets binding so we can reuse it again.

      void resetExtraction();
            /// Resets binding so we can reuse it again.

      template <class T, class C>
00193       void addInternalExtract(const MetaColumn& mc)
            /// Utility function to create and add an internal extraction.
      {
            std::vector<T>* pData = new C;
            Column<T>* pCol = new Column<T>(mc, pData);
            addExtract(new InternalExtraction<T>(*pData, pCol));
      }

      StatementImpl(const StatementImpl& stmt);
      StatementImpl& operator = (const StatementImpl& stmt);

      State                 _state;
      Limit                 _extrLimit;
      Poco::UInt32          _lowerLimit;
      int                   _columnsExtracted;
      std::ostringstream    _ostr;
      AbstractBindingVec    _bindings;
      AbstractExtractionVec _extractors;

      friend class Statement; 
};


//
// inlines
//
inline void StatementImpl::addBinding(AbstractBinding* info)
{
      _bindings.push_back(info);
}


00225 inline void StatementImpl::addExtract(AbstractExtraction* info)
{
      _extractors.push_back(info);
}


00231 inline std::string StatementImpl::toString() const
{
      return _ostr.str();
}


00237 inline const AbstractBindingVec& StatementImpl::bindings() const
{
      return _bindings;
}


00243 inline AbstractBindingVec& StatementImpl::bindings()
{
      return _bindings;
}


00249 inline const AbstractExtractionVec& StatementImpl::extractions() const
{
      return _extractors;
}


00255 inline AbstractExtractionVec& StatementImpl::extractions()
{
      return _extractors;
}


00261 inline int StatementImpl::columnsExtracted() const
{
      return _columnsExtracted;
}


00267 inline StatementImpl::State StatementImpl::getState() const
{
      return _state;
}


} } // namespace Poco::Data


#endif // Data_StatementImpl_INCLUDED

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