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Diffstat (limited to 'src/xmlpatterns/expr/qexternalvariableloader_p.h')
| -rw-r--r-- | src/xmlpatterns/expr/qexternalvariableloader_p.h | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/src/xmlpatterns/expr/qexternalvariableloader_p.h b/src/xmlpatterns/expr/qexternalvariableloader_p.h new file mode 100644 index 0000000..4eacd99 --- /dev/null +++ b/src/xmlpatterns/expr/qexternalvariableloader_p.h @@ -0,0 +1,139 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (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 either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** 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 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@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_ExternalVariableLoader_H +#define Patternist_ExternalVariableLoader_H + +#include "qitem_p.h" +#include "qsequencetype_p.h" +#include "qxmlname.h" + +QT_BEGIN_HEADER + +QT_BEGIN_NAMESPACE + +namespace QPatternist +{ + class DynamicContext; + + /** + * @short Responsible for loading and declaring available external variables. + * + * An external variable in XQuery is a global variable that has been declared to receive + * its value from the XQuery implementation, as opposed to an initializing expression. Here + * is an example of a query with an external variable declaration, followed by a ordinary + * global variable: + * + * <tt> declare variable $theName external; + * declare variable $theName := "the value"; + * "And here's the query body(a string literal)"</tt> + * + * An external variable declaration can also specify a sequence type: + * + * <tt>declare variable $theName as xs:integer external;</tt> + * + * This class allows the user to supply the values to external variables. When + * an external variable declaration occur in the query, + * announceExternalVariable() is called. + * + * @ingroup Patternist_xdm + * @author Frans Englich <fenglich@trolltech.com> + */ + class Q_AUTOTEST_EXPORT ExternalVariableLoader : public QSharedData + { + public: + typedef QExplicitlySharedDataPointer<ExternalVariableLoader> Ptr; + inline ExternalVariableLoader() {} + + virtual ~ExternalVariableLoader(); + + /** + * Called when Patternist encounters an external variable in the query. It is guaranteed + * to be called once for each external variable appearing in a query module. + * + * @param name the name of the variable. Quaranteed to never be @c null. + * @param declaredType the type that the user declared the variable to be of. Whether + * this type matches the actual value of the variable or not is irrelevant. Patternist + * will do the necessary error handling based on the sequence type that is returned from + * this function. If the user didn't declare a type, the type is <tt>item()*</tt>(zero or + * more items). Quaranteed to never be @c null. + * @returns the sequence type of the value this ExternalVariableLoader actually supplies. However, + * if the ExternalVariableLoader knows it cannot supply a variable by this name, @c null should be + * returned. + */ + virtual SequenceType::Ptr announceExternalVariable(const QXmlName name, + const SequenceType::Ptr &declaredType); + + /** + * This function is called at runtime when the external variable by name @p name needs + * to be evaluated. It is not defined how many times this function will be called. It + * depends on aspects such as how the query was optimized. + * + * @param name the name of the variable. Quaranteed to never be @c null. + * @param context the DynamicContext. + * @returns the value of the variable. Remember that this value must match the + * sequence type returned from announceExternalVariable() for the same name. + */ + virtual Item::Iterator::Ptr evaluateSequence(const QXmlName name, + const QExplicitlySharedDataPointer<DynamicContext> &context); + + virtual Item evaluateSingleton(const QXmlName name, + const QExplicitlySharedDataPointer<DynamicContext> &context); + virtual bool evaluateEBV(const QXmlName name, + const QExplicitlySharedDataPointer<DynamicContext> &context); + }; +} + +QT_END_NAMESPACE + +QT_END_HEADER + +#endif |