/sqlite3cc

/*

 * 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 ) ) );

		switch( column_type( index ) ) {

		case SQLITE_NULL:

			value = boost::get( boost::value_initialized< T >() );

			break;

		case SQLITE_BLOB: {

			int length = sqlite3_column_bytes( _handle, index );

			std::string string_value( static_cast< const char * >(

					sqlite3_column_blob( _handle, index ) ), length );

			value = boost::lexical_cast< T >( string_value );

			break;

		}

		default:

			const char *text = reinterpret_cast< const char * >(

				sqlite3_column_text( _handle, index ) );

			value = boost::lexical_cast< T >( text );

		}

	}

	/**

	 * 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_ */