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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> |
| */ |
| } |