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Branched from the monolithic repo, Qt master branch, at commit
896db169ea224deb96c59ce8af800d019de63f12

1 files changed, 146 insertions, 0 deletions

diff --git a/src/xmlpatterns/expr/qevaluationcache_p.h b/src/xmlpatterns/expr/qevaluationcache_p.h
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+++ b/src/xmlpatterns/expr/qevaluationcache_p.h
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+/****************************************************************************
+**
+** Copyright (C) 2011 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_EvaluationCache_H
+#define Patternist_EvaluationCache_H
+
+#include "qcachingiterator_p.h"
+#include "qcommonsequencetypes_p.h"
+#include "qnodebuilder_p.h"
+#include "qoperandsiterator_p.h"
+#include "qsinglecontainer_p.h"
+#include "qvariabledeclaration_p.h"
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+namespace QPatternist
+{
+    /**
+     * @short Evaluates to the same result as its operand, but ensures the
+     * operand is evaluated once even if this Expression is evaluated several
+     * times.
+     *
+     * EvaluationCache does this in a pipelined way, by delivering items from
+     * its cache, which is stored in the DynamicContext. If the cache has less
+     * items than what the caller requests, EvaluationCache continues to
+     * deliver but this time from the source, which it also populates into the
+     * cache.
+     *
+     * EvaluationCache is used as an optimization in order to avoid running
+     * expensive code paths multiple times, but also is sometimes a necessity:
+     * for instance, when objects must be unique, such as potentially in the
+     * case of node identity.
+     *
+     * EvaluationCache is in particular used for variables, whose sole purpose
+     * is to store it once(at least conceptually) and then use it in multiple
+     * places.
+     *
+     * In some cases an EvaluationCache isn't necessary. For instance, when a
+     * variable is only referenced once. In those cases EvaluationCache removes
+     * itself as an optimization; implemented in compress().
+     *
+     * @author Frans Englich <frans.englich@nokia.com>
+     * @ingroup Patternist_expressions
+     */
+    template<bool IsForGlobal>
+    class EvaluationCache : public SingleContainer
+    {
+    public:
+        EvaluationCache(const Expression::Ptr &operand,
+                        const VariableDeclaration::Ptr &varDecl,
+                        const VariableSlotID slot);
+
+        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
+        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
+        virtual Expression::Ptr compress(const StaticContext::Ptr &context);
+
+        virtual SequenceType::Ptr staticType() const;
+
+        /**
+         * The first operand must be exactly one @c xs:string.
+         */
+        virtual SequenceType::List expectedOperandTypes() const;
+
+        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
+        virtual Properties properties() const;
+        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
+                                          const SequenceType::Ptr &reqType);
+        virtual const SourceLocationReflection *actualReflection() const;
+
+        inline VariableSlotID slot() const
+        {
+            return m_varSlot;
+        }
+
+    private:
+        static DynamicContext::Ptr topFocusContext(const DynamicContext::Ptr &context);
+        const VariableDeclaration::Ptr  m_declaration;
+        /**
+         * This variable must not be called m_slot. If it so, a compiler bug on
+         * HP-UX-aCC-64 is triggered in the constructor initializor. See the
+         * preprocessor output.
+         *
+         * Note that this is the cache slot, and is disjoint to any variable's
+         * regular slot.
+         */
+        const VariableSlotID            m_varSlot;
+    };
+
+#include "qevaluationcache.cpp"
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif