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/*
* query.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_QUERY_H_
#define SQLITE3CC_QUERY_H_
#include <boost/iterator/iterator_facade.hpp>
#include <sqlite3cc/basic_statement.h>
#include <sqlite3cc/row.h>
namespace sqlite
{
class query
:
public detail::basic_statement
{
//______________________________________________________________________________
// instantiation
public:
/**
* Constructor that provides a connection upon which to act and the SQL
* query to execute.
*
* @param connection a reference to a connection
* @param sql an SQL statement in UTF-8
*/
explicit query(
connection &connection,
const std::string &sql );
/**
* Constructor that provides a connection upon which to act.
*
* @param connection a reference to a connection
*/
explicit query(
connection &connection );
//______________________________________________________________________________
// public interface
public:
/**
* Prepare an SQL statement.
*
* @param sql an SQL statement in UTF-8
* @returns an sqlite error code
* @see sqlite3_prepare_v2()
*/
virtual int prepare(
const std::string &sql );
/**
* Reset the statement, ready to re-execute it. This does not clear any of
* the values bound to the statement.
*
* @returns an sqlite error code
* @see sqlite3_reset()
*/
virtual int reset();
/**
* Perform a step() and return row object that can be used to retrieve the
* results.
*
* @return a row object
*/
row step();
/**
* Get the number of columns in the results.
*
* @see sqlite3_column_count()
*/
unsigned int column_count();
/**
* Get the name of a column in the results.
*
* @param index column index
* @see sqlite3_column_name()
*/
const std::string column_name(
unsigned int index );
/**
* Gets the number of results. Be aware that this merely step()s over the
* results and counts them, which is something you could do yourself. This
* method is intended to be used for convenience, where you only need know
* the number of results and not what they are. You could also execute some
* SQL like this: "SELECT COUNT(*) ...", but this only causes SQLite to
* internally do the same counting as this method does. Also note that this
* method reset()s the query.
*
* @returns the number of results
*/
unsigned long long num_results();
/**
* Query iterator which can be used to obtain rows.
*/
class iterator
:
public boost::iterator_facade< iterator, row,
boost::single_pass_traversal_tag, row >
{
public:
explicit iterator( query &query, bool step );
private:
friend class boost::iterator_core_access;
row dereference() const;
void increment();
bool equal( iterator const &other ) const;
/** the current row */
row _row;
/** the query */
query &_query;
};
/**
* Get an iterator to the initial row. Note that creating an iterator
* causes step() to be called, so it should only be called to begin
* iterating over the rows and not for comparison.
*
* @return a query iterator
*/
iterator begin();
/**
* Get an iterator to after the last row (i.e., an invalid row).
*
* @return an invalid query iterator
*/
iterator end();
//______________________________________________________________________________
// implementation
private:
/** next row number */
unsigned long long _next_row_number;
};
} // namespace sqlite
#endif /* SQLITE3CC_QUERY_H_ */
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