/**************************************************************************** | |
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** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). | |
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** This file is part of the QtXmlPatterns module of the Qt Toolkit. | |
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** GNU Lesser General Public License Usage | |
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** License version 2.1 as published by the Free Software Foundation and | |
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** file. Please review the following information to ensure the GNU Lesser | |
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** rights. These rights are described in the Nokia Qt LGPL Exception | |
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. | |
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** GNU General Public License Usage | |
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** file. Please review the following information to ensure the GNU General | |
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// | |
// 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 <frans.englich@nokia.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 |