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| ** Copyright (C) 2016 The Qt Company Ltd. |
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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 <private/qitem_p.h> |
| #include <private/qsequencetype_p.h> |
| #include <QXmlName> |
| |
| 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 |
| |
| #endif |