--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xmlpatterns/expr/qoptimizerframework_p.h Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,294 @@
+/****************************************************************************
+**
+** 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_OptimizerFramework_H
+#define Patternist_OptimizerFramework_H
+
+#include <QSharedData>
+
+#include "qexpression_p.h"
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+namespace QPatternist
+{
+ /**
+ * @short A factory for creating Expression instances.
+ *
+ * ExpressionIdentifier is one of the building block of Patternist's
+ * optimizer framework. An ExpressionIdentifier sub-class has
+ * the responsibility of creating the Expression that should be
+ * the result of the optimization.
+ *
+ * This class and sub-classes are never used on their own,
+ * but in cooperation with OptimizationPass.
+ *
+ * @author Frans englich <frans.englich@nokia.com>
+ * @ingroup Patternist_expressions
+ */
+ class ExpressionCreator : public QSharedData
+ {
+ public:
+ typedef QExplicitlySharedDataPointer<ExpressionCreator> Ptr;
+
+ /**
+ * For some reason this constructor cannot be synthesized.
+ */
+ inline ExpressionCreator()
+ {
+ }
+
+ virtual ~ExpressionCreator();
+ /**
+ * Creates an expression that has @p operands as operands.
+ *
+ * The Expression that is returned is guaranteed, by the caller,
+ * to get a treatment identical to if the expression was created
+ * in an ordinary compilation(via the parser, and so forth). That is,
+ * Expression::typeCheck() and Expression::compress() stages will be
+ * carried out on the returned expression.
+ *
+ * @returns an Expression::Ptr that never is non @c null, valid pointer
+ */
+ virtual Expression::Ptr create(const Expression::List &operands,
+ const StaticContext::Ptr &context,
+ const SourceLocationReflection *const) const = 0;
+
+ private:
+ Q_DISABLE_COPY(ExpressionCreator)
+ };
+
+ /**
+ * @short Abstract base class for all classes that identify Expressions
+ * based on some criteria.
+ *
+ * ExpressionIdentifier is one of the building block of Patternist's
+ * optimizer framework. An ExpressionIdentifier sub-class has
+ * the responsibility of determining whether a particular Expression
+ * is the one an OptimizationPass should apply for.
+ *
+ * This class and sub-classes are never used on their own,
+ * but in cooperation with OptimizationPass.
+ *
+ * @author Frans englich <frans.englich@nokia.com>
+ * @ingroup Patternist_expressions
+ */
+ class ExpressionIdentifier : public QSharedData
+ {
+ public:
+ typedef QExplicitlySharedDataPointer<ExpressionIdentifier> Ptr;
+ typedef QList<ExpressionIdentifier::Ptr> List;
+
+ /**
+ * For some reason this constructor cannot be synthesized.
+ */
+ inline ExpressionIdentifier()
+ {
+ }
+
+ virtual ~ExpressionIdentifier();
+ /**
+ * @param expr the Expression to be tested. This is guranteed
+ * to always be a non @c null, valid pointer.
+ *
+ * @returns @c true if @p expr matches as according to this ExpressionIdentifier,
+ * otherwise @c false.
+ */
+ virtual bool matches(const Expression::Ptr &expr) const = 0;
+
+ private:
+ Q_DISABLE_COPY(ExpressionIdentifier)
+ };
+
+ /**
+ * @short Describes how a particular optimization pass should be carried out.
+ *
+ * OptimizationPass is essentially a declaration, which describes
+ * how an optimization pass in the form of an AST rewrite should be done,
+ * by describing what that should be rewritten into what how.
+ *
+ * Each OptimizationPass is applied to a "start" Expression. The Expression
+ * that qualifies as a start Expression for the OptimizationPass in question is
+ * determined by startIdentifier; if its ExpressionIdentifier::matches() function
+ * returns @c true, the optimizer continues to apply this OptimizationPass.
+ *
+ * After a start Expression has been found, it is verified if the operands matches
+ * as well by applying the ExpressionIdentifiers in operandIdentifiers to the
+ * start Expression's operands. Similarly, if the operands matches what
+ * operandIdentifiers requires, the optimizer continues to apply this OptimizationPass.
+ *
+ * At this stage, it has been concluded that the OptimizationPass validly applies, and
+ * what now remains is to carry out the actual rewrite. The Expression rewritten
+ * to is the one returned by ExpressionCreator::create(), when invoked via the resultCreator
+ * variable.
+ *
+ * How these components, startIdentifier, operandIdentifiers, sourceExpression,
+ * and resultCreator interacts with one another is described in more detail
+ * in the member documentation as well as the classes they are instances of.
+ *
+ * @author Frans englich <frans.englich@nokia.com>
+ * @ingroup Patternist_expressions
+ */
+ class OptimizationPass : public QSharedData
+ {
+ public:
+ typedef QExplicitlySharedDataPointer<OptimizationPass> Ptr;
+ typedef QList<OptimizationPass::Ptr> List;
+
+ enum OperandsMatchMethod
+ {
+ /**
+ * All operands must match in the same order the ExpressionMarkers do.
+ */
+ Sequential = 1,
+
+ /**
+ * Matches if all operands are matched, regardless of their order. This is
+ * useful when an OptimizationPass is matching an Expression that has two operands
+ * and that both of them can appear on the left or right hand as long as it is those
+ * two.
+ *
+ * This comparison method only works when two operands
+ * needs to be matched.
+ */
+ AnyOrder
+ };
+
+ /**
+ * An ExpressionMarker identifies an operand Expression relatively
+ * the start Expression by that each integer identifies a step
+ * in a descending AST walk. For example an ExpressionMarker with
+ * only one entry that is 0(zero), identifies the first operand of the
+ * start Expression. An ExpressionMarker containing 1, 2 in that order
+ * identifies the third operand of the second operand of the start Expression.
+ */
+ typedef QList<qint8> ExpressionMarker;
+
+ /**
+ * Creates an OptimizationPass and sets its public variables
+ * to the corresponding values passed in this constructor.
+ */
+ OptimizationPass(const ExpressionIdentifier::Ptr &startID,
+ const ExpressionIdentifier::List &operandIDs,
+ const ExpressionMarker &sourceExpr,
+ const ExpressionCreator::Ptr &resultCtor = ExpressionCreator::Ptr(),
+ const OperandsMatchMethod matchMethod = Sequential);
+
+ /**
+ * The ExpressionIdentifier that must the Expression this OptimizationPass concerns.
+ *
+ * If this variable is @c null, it means that the start Expression does
+ * not have to match any particular ExpressionIdentifier, but is fine as is.
+ *
+ * One might wonder what the purpose of this startIdentifier is, considering
+ * that what start Expression an OptimizationPass can at all apply to is
+ * naturally determined by what Expression::optimizationPasses() re-implementation that
+ * returns this OptimizationPass. The reason is that in some cases an OptimizationPass
+ * nevertheless doesn't apply. For example, optimizations applying to a ValueComparison
+ * might depend on what operator that is in use.
+ *
+ * May be @c null or point to an ExpressionIdentifier.
+ */
+ const ExpressionIdentifier::Ptr startIdentifier;
+
+ /**
+ * In order for an OptimizationPass to apply, the start Expression's
+ * operands must be matched with this list of ExpressionIdentifier instances.
+ * The first ExpressionIdentifier is applied to the first operand, the second
+ * ExpressionIdentifier to the second operand, and so forth until all operands
+ * have been iterated.
+ *
+ * Entries in this list may be @c null, and those signals that the corresponding
+ * operand is not constrained. For example, if the third ExpressionIdentifier in
+ * the list is @c null, it signals that the third operand may be anykind of expression.
+ *
+ * May be empty or contain an arbitrary amount of objects or @c null pointers.
+ */
+ const ExpressionIdentifier::List operandIdentifiers;
+
+ /**
+ * Identifies the expression that should be part of the new expression
+ * that this OptimizationPass rewrites to. If this list is empty, it
+ * means that the result is not derived from the existing tree, and
+ * that resultCreator will exclusively be used for creating the result
+ * Expression.
+ *
+ * How the ExpressionMarker identifies an Expression is document in
+ * its documentation.
+ *
+ * May be empty.
+ */
+ const ExpressionMarker sourceExpression;
+
+ /**
+ * This is the ExpressionCreator that will be used to create the
+ * Expression which is the result. ExpressionCreator::create()
+ * will be passed as operands the Expression that sourceExpression
+ * specify, if any.
+ *
+ * If this variable is @c null, the result Expression will be the one
+ * sourceExpression identifies.
+ */
+ const ExpressionCreator::Ptr resultCreator;
+
+ const OperandsMatchMethod operandsMatchMethod;
+ private:
+ Q_DISABLE_COPY(OptimizationPass)
+ };
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif