| /**************************************************************************** |
| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
| ** Contact: https://www.qt.io/licensing/ |
| ** |
| ** 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 The Qt Company. For licensing terms |
| ** and conditions see https://www.qt.io/terms-conditions. For further |
| ** information use the contact form at https://www.qt.io/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 3 as published by the Free Software |
| ** Foundation and appearing in the file LICENSE.LGPL3 included in the |
| ** packaging of this file. Please review the following information to |
| ** ensure the GNU Lesser General Public License version 3 requirements |
| ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. |
| ** |
| ** GNU General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU |
| ** General Public License version 2.0 or (at your option) the GNU General |
| ** Public license version 3 or any later version approved by the KDE Free |
| ** Qt Foundation. The licenses are as published by the Free Software |
| ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 |
| ** included in the packaging of this file. Please review the following |
| ** information to ensure the GNU General Public License requirements will |
| ** be met: https://www.gnu.org/licenses/gpl-2.0.html and |
| ** https://www.gnu.org/licenses/gpl-3.0.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. |
| |
| #ifndef Patternist_EvaluationCache_H |
| #define Patternist_EvaluationCache_H |
| |
| #include <private/qcachingiterator_p.h> |
| #include <private/qcommonsequencetypes_p.h> |
| #include <private/qnodebuilder_p.h> |
| #include <private/qoperandsiterator_p.h> |
| #include <private/qsinglecontainer_p.h> |
| #include <private/qvariabledeclaration_p.h> |
| |
| 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_tpl_p.h" |
| } |
| |
| QT_END_NAMESPACE |
| |
| #endif |