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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
/**
* @file
* @short Contains Doxygen documentation for groups.
*/
namespace QPatternist
{
/**
* @short The abstract syntax tree nodes that implements the builtin
* functions, such as @c fn:concat().
*
* @defgroup Patternist_functions Function Implementations
* @author Frans Englich <frans.englich@nokia.com>
*/
/**
* @short The abstract syntax tree nodes that is generated for XPath,
* XQuery, and XSL-T code.
*
* XPath's approach of compilation is traditional. An Abstract Syntax
* Tree(AST) is built, where the Expression class is the abstract base
* class for all kinds of implementations of expressions.
*
* What perhaps can be said to be characteristic for Patternist is that the
* base class, Expression, performs a lot of work, and that sub-classes
* declares what specific behaviors they need, which the Expression's
* functions then bring into action.
*
* XPath expressions often have different amount of operands. For example,
* the 'and' expression takes two, the context item(".") none, and the
* if-expression three. To help expression implementations with that, there
* exist the abstract EmptyContainer, SingleContainer, PairContainer,
* TripleContainer, and UnlimitedContainer classes for avoiding duplicating
* code.
*
* @defgroup Patternist_expressions Expressions
* @author Frans Englich <frans.englich@nokia.com>
*/
/**
* @short Various classes that contains small utility functions.
*
* @defgroup Patternist Utility Classes
* @author Frans Englich <frans.englich@nokia.com>
*/
/**
* @short Classes for the type system in the XQuery & XSL-T language.
*
* @defgroup Patternist_types Type system
* @author Frans Englich <frans.englich@nokia.com>
*/
/**
* @defgroup Patternist_xdm XQuery/XPath Data Model
* @author Frans Englich <frans.englich@nokia.com>
*/
/**
* @short Patternist's family of iterators in one of the most central parts
* of Patternist's API, and are responsible for carrying, and typically
* also creating, data.
*
* An iterator, which always is an Iterator sub-class, is similar to a
* Java-style iterator. What signifies Patternist's iterators is that they
* almost always contains business logic(which is the cause to their
* efficiency).
*
* An example which illustrates this principle is the RangeIterator. When
* the RangeExpression is told to create a sequence of integers between 1
* and 1000, it doesn't enter a loop that allocates 1000 Integer instances,
* but instead return an RangeIterator that incrementally creates the
* numbers when asked to do so via its RangeIterator::next() function. If
* it turns out that the expression that has the range expression as
* operand only needs three items from it, that is what gets created, not
* 1000.
*
* All iterators operates by that principle, perhaps suitably labeled as
* "pull-based", "lazy loaded" or "serialized". Central for the XPath
* language is that it filters and selects data, and the iterators supports
* this well by letting the demand of the filter expressions(the callees)
* decide how "much" source that gets computed. In this way the evaluation
* of an expression tree can lead to a chain of pipelined iterators, where
* the first asks the second for data and then performs its specific
* operations, the second subsequently asks the third, and so forth.
*
* However, the iterators are not limited to be used for representing
* sequences of items in the XPath Data Model. The Iterator is
* parameterized on one argument, meaning any type of "units" can be
* iterated, be it Item or any other. One use of this is in the
* ExpressionSequence(which implements the comma operator) where it creates
* Iterator instances over Expression instances -- its operands. The
* parameterization is often used in combination with the MappingIterator
* and the MappingCallback.
*
* @defgroup Patternist_iterators Iterators
* @author Frans Englich <frans.englich@nokia.com>
*/
}
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