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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#ifndef Patternist_FunctionSignature_H
51#define Patternist_FunctionSignature_H
52
53#include <QSharedData>
54
55#include <private/qcalltargetdescription_p.h>
56#include <private/qexpression_p.h>
57#include <private/qfunctionargument_p.h>
58#include <private/qpatternistlocale_p.h>
59#include <private/qprimitives_p.h>
60
61QT_BEGIN_NAMESPACE
62
63template<typename Key, typename Value> class QHash;
64template<typename T> class QList;
65
66namespace QPatternist
67{
68
69 /**
70 * @short Represents the signature of an XPath function.
71 *
72 * FunctionSignature represents and allows inspection of a function signature,
73 * such as <tt>fn:string-join($arg1 as xs:string*, $arg2 as xs:string) as xs:string</tt>.
74 * No XPath related languages allows polymorphism on the type of the arguments, only the
75 * amount(arity) of the arguments. For example, <tt>fn:string() as xs:string</tt> and
76 * <tt>fn:string($arg as item()?) as xs:string</tt> can happily co-exist, but
77 * <tt>fn:string($arg as item()?) as xs:string</tt> and
78 * <tt>fn:string($arg as xs:anyAtomicType?) as xs:string</tt> would be an error. This
79 * fact is reflected by FunctionSignature that if minimumArguments() and maximumArguments()
80 * are not equal, it means that this FunctionSignature represents several
81 * function signatures.
82 *
83 * @ingroup Patternist_functions
84 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-signatures">XQuery 1.0 and
85 * XPath 2.0 Functions and Operators, 1.4 Function Signatures and Descriptions</a>
86 * @see <a href="http://en.wikipedia.org/wiki/Arity">Wikipedia, the free encyclopedia, Arity</a>
87 * @author Frans Englich <frans.englich@nokia.com>
88 */
89 class Q_AUTOTEST_EXPORT FunctionSignature : public CallTargetDescription
90 {
91 public:
92 enum
93 {
94 /**
95 * Flags the function as allowing an unlimited amount of arguments.
96 */
97 UnlimitedArity = -1
98 };
99
100 typedef QExplicitlySharedDataPointer<FunctionSignature> Ptr;
101 typedef QHash<QXmlName, FunctionSignature::Ptr> Hash;
102 typedef QList<FunctionSignature::Ptr> List;
103
104 /**
105 * A number which tells the amount of arguments a function has.
106 */
107 typedef qint16 Arity;
108
109 FunctionSignature(const QXmlName name,
110 const Arity minArgs,
111 const Arity maxArgs,
112 const SequenceType::Ptr &returnType,
113 const Expression::Properties chars = Expression::Properties(),
114 const Expression::ID id = Expression::IDIgnorableExpression);
115
116 void setArguments(const FunctionArgument::List &args);
117 FunctionArgument::List arguments() const;
118
119 /**
120 * This is a convenience function. Calling this once, is equal to
121 * calling setArguments() with a list containing a FunctionsArgument with name @p name
122 * and type @p type.
123 */
124 void appendArgument(const QXmlName::LocalNameCode name,
125 const SequenceType::Ptr &type);
126
127 /**
128 * Checks whether @p arity is within the range of allowed count of arguments. For example,
129 * when the minimum arguments is 1 and maximum arguments 2, @c false will be returned for
130 * passing 0 while @c true will be returned when 2 is passed.
131 */
132 bool isArityValid(const xsInteger arity) const;
133
134 Arity minimumArguments() const;
135 Arity maximumArguments() const;
136
137 /**
138 * The return type of this function signature. For example, if the represented function
139 * signature is <tt>fn:string() as xs:string</tt>, the return type is <tt>xs:string</tt>.
140 */
141 SequenceType::Ptr returnType() const;
142
143 /**
144 * The properties that the corresponding FunctionCall instance should return in
145 * Expression::properties().
146 */
147 Expression::Properties properties() const;
148
149 /**
150 * Determines whether this FunctionSignature is equal to @p other, taking
151 * into account XPath's function polymorphism. @p other is equal to this
152 * FunctionSignature if their name() instances are equal, and that the maximumArguments()
153 * and minimumArguments() arguments of @p other are allowed, as per isArityValid().
154 *
155 * In other words, this equalness operator can return @c true for different
156 * signatures, but it do make sense since a FunctionSignature can represent
157 * multiple signatures.
158 *
159 * @returns @c true if this FunctionSignature is equal to @p other, otherwise @c false
160 */
161 bool operator==(const FunctionSignature &other) const;
162
163 /**
164 * Builds a string representation for this function signature. The syntax
165 * used is the one used in the XQuery. It looks like this:
166 *
167 * <tt>prefix:function-name($parameter-name as parameter-type, ...) as return-type</tt>
168 *
169 * The prefix used for the name is conventional. For example, for constructor functions
170 * is @c xs used.
171 *
172 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-signatures">XQuery 1.0 and
173 * XPath 2.0 Functions and Operators, 1.4 Function Signatures and Descriptions</a>
174 */
175 QString displayName(const NamePool::Ptr &np) const;
176
177 /**
178 * The ID that the corresponding FunctionCall instance should return in
179 * Expression::id().
180 */
181 Expression::ID id() const;
182
183 private:
184 Q_DISABLE_COPY(FunctionSignature)
185
186 const Arity m_minArgs;
187 const Arity m_maxArgs;
188 const SequenceType::Ptr m_returnType;
189 FunctionArgument::List m_arguments;
190 const Expression::Properties m_props;
191 const Expression::ID m_id;
192 };
193
194 /**
195 * @short Formats FunctionSignature.
196 */
197 static inline QString formatFunction(const NamePool::Ptr &np, const FunctionSignature::Ptr &func)
198 {
199 return QLatin1String("<span class='XQuery-function'>") +
200 escape(input: func->displayName(np)) +
201 QLatin1String("</span>");
202 }
203}
204
205QT_END_NAMESPACE
206
207#endif
208

source code of qtxmlpatterns/src/xmlpatterns/functions/qfunctionsignature_p.h