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//

//  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>

     */

}