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/*
* row.h
*
* Copyright (C) 2009 Tim Marston <edam@waxworlds.org>
*
* This file is part of sqlite3cc (hereafter referred to as "this program").
* See http://www.waxworlds.org/edam/software/sqlite3cc for more information.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SQLITE3CC_ROW_H_
#define SQLITE3CC_ROW_H_
#include <sqlite3cc/query.h>
#include <sqlite3.h>
#include <boost/utility.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/utility/value_init.hpp>
#include <cassert>
#include <iostream>
namespace sqlite
{
struct _null_t;
struct _set_index_t;
/**
* A result row from a query.
*
* The row is only valid until the next call to step() or reset() on the parent
* query object, or until the parent query object is destructed. This may change
* in future versions.
*/
class row
{
//______________________________________________________________________________
// instantiation
protected:
/**
* Constructor that provides the database that we were extracted from.
* @param the query that this row belongs to
* @oaram true if this row represents there being no more rows
*/
explicit row(
query &query,
bool valid = true );
//______________________________________________________________________________
// public interface
public:
/**
* Determine if this row is valid or not. If it is not valid, there are no
* more rows in the results of the query.
*/
inline operator bool()
{
return _valid;
}
/**
* Ascertain a column's type.
* @param index column index
* @return sqlite datatype code
* @see sqlite3_column_type()
*/
int column_type(
unsigned int index );
/**
* get the number of bytes in the result for a given column.
* @param index column index
* @return number of bytes in result
* @see sqlite3_column_bytes()
*/
unsigned int column_bytes(
unsigned int index );
/**
* Get a value from the row
* @param index column index
* @param value reference to object to set with the value
* @see sqlite3_column_*()
*/
template< class T >
void column(
unsigned int index,
T &value )
{
assert( index < _query.column_count() );
const char *text = reinterpret_cast< const char * >(
sqlite3_column_text( _query._handle, index ) );
if( text )
value = boost::lexical_cast< T >( text );
else
value = boost::get( boost::value_initialized< T >() );
}
/**
* Stream operator is used to obtain values from a result row, fetching from
* each column in turn. In addition, the null and set_index() auto-column-
* getting manipulators can be used.
* @param value is a variable to store the retrieved data in
*/
template< class T >
row &operator >>(
T &value )
{
column( _column_index, value );
_column_index++;
return *this;
}
/**
* Stream operator for use with set_index().
*/
row &operator >>(
_set_index_t t );
/**
* Check of this row is valid
* @return true if it is
*/
operator bool() const
{
return _valid;
}
//______________________________________________________________________________
// implementation
protected:
friend class query;
/** the parent query */
query &_query;
private:
/** index used when auto-column-getting */
unsigned int _column_index;
/** is this row valid? */
bool _valid;
};
// template specialisations
template< >
row &row::operator >> < _null_t >(
_null_t & );
} // namespace row
#endif /* SQLITE3CC_ROW_H_ */
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