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/*
* row.h
*
* Copyright (C) 2009 Tim Marston <tim@ed.am>
*
* This file is part of sqlite3cc (hereafter referred to as "this program").
* See http://ed.am/dev/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 <sqlite3.h>
#include <boost/utility.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/utility/value_init.hpp>
#include <cassert>
#include <iostream>
namespace sqlite
{
class query;
namespace detail {
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:
friend class query;
/**
* Constructor that produces a valid row.
*
* @param handle of the statement (query) that created this row
* @oaram row_number the index of this row
*/
explicit row(
sqlite3_stmt *handle,
unsigned long long row_number );
/**
* Constructor that produces an invalid row.
*/
explicit row();
//______________________________________________________________________________
// 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.
*/
operator bool() const;
/**
* Get the index in to the results that is this row.
*
* @return index
*/
inline unsigned long long row_number()
{
return _row_number;
}
/**
* 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 <
static_cast< unsigned int >( sqlite3_column_count( _handle ) ) );
const char *text = reinterpret_cast< const char * >(
sqlite3_column_text( _handle, index ) );
if( text )
value = boost::lexical_cast< T >( text );
else
value = boost::get( boost::value_initialized< T >() );
}
/**
* Get a value from the row and return it.
*
* @param index column index
* @return the value
* @see sqlite3_column_*()
*/
template< class T >
T column(
unsigned int index )
{
T value;
column( index, value );
return value;
}
/**
* 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 >>(
detail::set_index_t t );
/**
* Test to see if two rows are the same.
*
* @param other the row to compare this one to
* @return true if they are
*/
bool operator ==(
const row &other )
const;
//______________________________________________________________________________
// implementation
protected:
/** the query's handle, or NULL */
sqlite3_stmt *_handle;
private:
/** index used when auto-column-getting */
unsigned int _column_index;
/** the index of this row */
unsigned long long _row_number;
};
// template specialisations
template< >
row &row::operator >> < detail::null_t >(
detail::null_t & );
} // namespace sqlite
#endif /* SQLITE3CC_ROW_H_ */
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