bzr branch
http://bzr.ed.am/sqlite3cc
2
by edam
- further initial development |
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/* |
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* row.h |
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* |
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* Copyright (C) 2009 Tim Marston <edam@waxworlds.org> |
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* |
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* This file is part of sqlite3cc (hereafter referred to as "this program"). |
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* See http://www.waxworlds.org/edam/software/sqlite3cc for more information. |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser General Public License as published |
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* by the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>. |
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*/ |
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#ifndef SQLITE3CC_ROW_H_ |
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#define SQLITE3CC_ROW_H_ |
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#include <sqlite3cc/query.h> |
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#include <sqlite3.h> |
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#include <boost/utility.hpp> |
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#include <boost/lexical_cast.hpp> |
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#include <boost/utility/value_init.hpp> |
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#include <cassert> |
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#include <iostream> |
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namespace sqlite |
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{ |
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struct _null_t; |
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struct _set_index_t; |
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/** |
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* A result row from a query. |
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* |
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* The row is only valid until the next call to step() or reset() on the parent |
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* query object, or until the parent query object is destructed. This may change |
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* in future versions. |
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*/ |
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class row |
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{ |
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//______________________________________________________________________________ |
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// instantiation |
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protected: |
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/** |
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* Constructor that provides the database that we were extracted from. |
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* @param the query that this row belongs to |
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* @oaram true if this row represents there being no more rows |
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*/ |
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explicit row( |
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query &query, |
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bool valid = true ); |
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//______________________________________________________________________________ |
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// public interface |
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public: |
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/** |
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* Determine if this row is valid or not. If it is not valid, there are no |
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* more rows in the results of the query. |
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*/ |
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inline operator bool() |
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{ |
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return _valid; |
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} |
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/** |
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* Ascertain a column's type. |
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* @param index column index |
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* @return sqlite datatype code |
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* @see sqlite3_column_type() |
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*/ |
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int column_type( |
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unsigned int index ); |
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/** |
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* get the number of bytes in the result for a given column. |
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* @param index column index |
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* @return number of bytes in result |
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* @see sqlite3_column_bytes() |
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*/ |
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unsigned int column_bytes( |
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unsigned int index ); |
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/** |
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* Get a value from the row |
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* @param index column index |
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* @param value reference to object to set with the value |
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* @see sqlite3_column_*() |
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*/ |
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template< class T > |
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void column( |
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unsigned int index, |
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T &value ) |
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{ |
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assert( index < _query.column_count() ); |
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const char *text = reinterpret_cast< const char * >( |
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sqlite3_column_text( _query._handle, index ) ); |
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if( text ) |
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value = boost::lexical_cast< T >( text ); |
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else |
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value = boost::get( boost::value_initialized< T >() ); |
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} |
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/** |
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* Stream operator is used to obtain values from a result row, fetching from |
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* each column in turn. In addition, the null and set_index() auto-column- |
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* getting manipulators can be used. |
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* @param value is a variable to store the retrieved data in |
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*/ |
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template< class T > |
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row &operator >>( |
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T &value ) |
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{ |
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column( _column_index, value ); |
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_column_index++; |
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return *this; |
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} |
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/** |
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* Stream operator for use with set_index(). |
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*/ |
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row &operator >>( |
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_set_index_t t ); |
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/** |
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* Check of this row is valid |
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* @return true if it is |
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*/ |
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operator bool() const |
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{ |
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return _valid; |
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} |
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//______________________________________________________________________________ |
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// implementation |
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protected: |
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friend class query; |
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/** the parent query */ |
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query &_query; |
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private: |
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/** index used when auto-column-getting */ |
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unsigned int _column_index; |
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/** is this row valid? */ |
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bool _valid; |
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}; |
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// template specialisations |
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template< > |
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row &row::operator >> < _null_t >( |
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_null_t & ); |
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} // namespace row |
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#endif /* SQLITE3CC_ROW_H_ */ |