src/xmlpatterns/expr/qgenericpredicate_p.h
changeset 0 1918ee327afb
child 4 3b1da2848fc7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xmlpatterns/expr/qgenericpredicate_p.h	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,148 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtXmlPatterns module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** 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, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//
+//  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.
+
+#ifndef Patternist_GenericPredicate_H
+#define Patternist_GenericPredicate_H
+
+#include "qpaircontainer_p.h"
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+namespace QPatternist
+{
+    /**
+     * @short A predicate that can handle all kinds of predicates and
+     * is therefore not very efficient, but can cope with all the tricky scenarios.
+     *
+     * @see FirstItemPredicate
+     * @see TruthPredicate
+     * @author Frans Englich <frans.englich@nokia.com>
+     * @ingroup Patternist_expressions
+     */
+    class GenericPredicate : public PairContainer
+    {
+    public:
+
+        /**
+         * Creates a predicate expression that filters the items gained
+         * from evaluating @p sourceExpression through the filter @p predicateExpression.
+         *
+         * This function performs type analyzis on the passed expressions, and may
+         * return more specialized expressions depending on the analyzis.
+         *
+         * If @p predicateExpression is an invalid predicate, an error is issued
+         * via the @p context.
+         */
+        static Expression::Ptr create(const Expression::Ptr &sourceExpression,
+                                      const Expression::Ptr &predicateExpression,
+                                      const StaticContext::Ptr &context,
+                                      const QSourceLocation &location);
+
+        static Expression::Ptr createFirstItem(const Expression::Ptr &sourceExpression);
+
+        /**
+         * Creates a source iterator which is passed to the ItemMappingIterator
+         * and the Focus. The ItemMappingIterator modifies it with
+         * its QAbstractXmlForwardIterator::next() calls, and since the Focus references the same QAbstractXmlForwardIterator,
+         * the focus is automatically moved.
+         */
+        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
+
+        /**
+         * Doesn't return the first item from calling evaluateSequence(), but does the mapping
+         * manually. This avoid allocating an ItemMappingIterator.
+         */
+        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
+
+        inline Item mapToItem(const Item &subject,
+                                   const DynamicContext::Ptr &) const;
+
+        virtual SequenceType::List expectedOperandTypes() const;
+        virtual SequenceType::Ptr staticType() const;
+        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
+        virtual ID id() const;
+
+        /**
+         * @returns always CreatesFocusForLast.
+         */
+        virtual Properties properties() const;
+
+        virtual QString description() const;
+
+    protected:
+
+        /**
+         * Creates a GenericPredicate which filters the items from the @p sourceExpression
+         * through @p predicate.
+         *
+         * This constructor is protected. The proper way to create predicates is via the static
+         * create() function.
+         */
+        GenericPredicate(const Expression::Ptr &sourceExpression,
+                         const Expression::Ptr &predicate);
+
+        /**
+         * @returns the ItemType of the first operand's staticType().
+         */
+        virtual ItemType::Ptr newFocusType() const;
+
+    private:
+        typedef QExplicitlySharedDataPointer<const GenericPredicate> ConstPtr;
+    };
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif