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39 
40 //
41 //  W A R N I N G
42 //  -------------
43 //
44 // This file is not part of the Qt API.  It exists purely as an
45 // implementation detail.  This header file may change from version to
46 // version without notice, or even be removed.
47 //
48 // We mean it.
49 
50 
51 #ifndef Patternist_FunctionFactory_H
52 #define Patternist_FunctionFactory_H
53 
54 #include <QHash>
55 #include <QSharedData>
56 
57 #include <private/qexpression_p.h>
58 #include <private/qfunctionsignature_p.h>
59 #include <private/qprimitives_p.h>
60 #include <QXmlName>
61 
62 QT_BEGIN_NAMESPACE
63 
64 namespace QPatternist
65 {
66 
67     /**
68      * @short An entry point for looking up and creating FunctionCall instances.
69      *
70      * @ingroup Patternist_functions
71      * @see <a href ="http://www.w3.org/TR/xpath-functions/">XQuery 1.0
72      * and XPath 2.0 Functions and Operators</a>
73      * @see <a href="http://www.w3.org/TR/xpath20/#dt-function-signature">XML Path
74      * Language (XPath) 2.0, Definition: Function signatures</a>
75      * @author Frans Englich <frans.englich@nokia.com>
76      */
77     class Q_AUTOTEST_EXPORT FunctionFactory : public QSharedData
78     {
79     public:
80 
81         typedef QExplicitlySharedDataPointer<FunctionFactory> Ptr;
82         typedef QList<FunctionFactory::Ptr> List;
83 
84         virtual ~FunctionFactory();
85 
86         /**
87          * Creates a function call implementation.
88          *
89          * A FunctionFactory represents a set of functions, which it
90          * is able to instantiate and to serve FunctionSignatures for. Conventionally,
91          * a FunctionFactory per namespace exists.
92          *
93          * @note This function should not issue any error unless it is absolutely
94          * confident that the error cannot be fixed in another way. For example, in
95          * some cases it might be that a function is available in another FunctionFactory
96          * and it would therefore be wrong to issue an error signalling that no function
97          * by that @p name exists, but leave that to the callee.
98          * @param name the name of the function to create. In Clark syntax, this could
99          * for example be {http://www.w3.org/2005/04/xpath-functions}lower-case
100          * @param arguments the function's operands
101          * @param context the usual StaticContext which supplies compile time data
102          * and reporting functionality.
103          * @param r the SourceLocationReflection that identifies the callsite.
104          * @returns an instance of Expression which is the function implementation
105          * for @p name. Or, a static error was raised.
106          */
107         virtual Expression::Ptr createFunctionCall(const QXmlName name,
108                                                    const Expression::List &arguments,
109                                                    const StaticContext::Ptr &context,
110                                                    const SourceLocationReflection *const r) = 0;
111 
112         /**
113          * Determines whether a function with the name @p name and arity @p arity
114          * is available. The implementation operates on the result of
115          * retrieveFunctionSignature() to determine the result.
116          *
117          * @param np the NamePool.
118          * @param name the name of the function. For example fn:string-join.
119          * @param arity the number of arguments the function must have.
120          */
121         virtual bool isAvailable(const NamePool::Ptr &np,
122                                  const QXmlName name,
123                                  const xsInteger arity);
124 
125         virtual FunctionSignature::Hash functionSignatures() const = 0;
126 
127         /**
128          * Determines whether this FunctionFactory contains the function signature
129          * @p signature.
130          *
131          * The implementation uses functionSignatures().
132          */
133         bool hasSignature(const FunctionSignature::Ptr &signature) const;
134 
135     protected:
136         /**
137          * @short This constructor cannot be removed, because it can't be synthesized, for
138          * some reason.
139          */
FunctionFactory()140         inline FunctionFactory()
141         {
142         }
143 
144         /**
145          * This is a convenience function for sub-classes. It retrieves the
146          * function signature for function with name @p name.
147          *
148          * According to the specifications are function signatures identified by their
149          * name and arity, but currently is the arity not part of the signature.
150          *
151          * If no function could be found for the given name, @c null is returned.
152          */
153         virtual FunctionSignature::Ptr retrieveFunctionSignature(const NamePool::Ptr &np, const QXmlName name) = 0;
154 
155     private:
156         Q_DISABLE_COPY(FunctionFactory)
157     };
158 }
159 
160 QT_END_NAMESPACE
161 
162 #endif
163