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39
40#include "private/qobject_p.h"
41#include "qabstractmessagehandler.h"
42
43QT_BEGIN_NAMESPACE
44
45/*!
46 \class QAbstractMessageHandler
47 \since 4.4
48 \ingroup xml-tools
49 \inmodule QtXmlPatterns
50 \brief The QAbstractMessageHandler class provides a callback interface for handling messages.
51
52 QAbstractMessageHandler is an abstract base class that provides a
53 callback interface for handling messages. For example, class
54 QXmlQuery parses and runs an XQuery. When it detects a compile
55 or runtime error, it generates an appropriate error message,
56 but rather than output the message itself, it passes the message to
57 the message() function of its QAbstractMessageHandler.
58 See QXmlQuery::setMessageHandler().
59
60 You create a message handler by subclassing QAbstractMessageHandler
61 and implementing handleMessage(). You then pass a pointer to an
62 instance of your subclass to any classes that must generate
63 messages. The messages are sent to the message handler via the
64 message() function, which forwards them to your handleMessge().
65
66 A single instance of QAbstractMessageHandler can be called on to
67 handle messages from multiple sources. Hence, the content of a
68 message, which is the \e description parameter passed to message()
69 and handleMessage(), must be interpreted in light of the context
70 that required the message to be sent. That context is specified by
71 the \e identifier and \e sourceLocation parameters to message()
72 handleMessage().
73 */
74
75/*!
76 Constructs a QAbstractMessageHandler. The \a parent is passed
77 to the QObject base class constructor.
78 */
79QAbstractMessageHandler::QAbstractMessageHandler(QObject *parent) : QObject(parent)
80{
81}
82
83/*!
84 Destructs this QAbstractMessageHandler.
85 */
86QAbstractMessageHandler::~QAbstractMessageHandler()
87{
88}
89
90/*!
91 Sends a message to this message handler. \a type is the kind of
92 message being sent. \a description is the message content. The \a
93 identifier is a URI that identifies the message and is the key to
94 interpreting the other arguments.
95
96 Typically, this class is used for reporting errors, as is the case
97 for QXmlQuery, which uses a QAbstractMessageHandler to report
98 compile and runtime XQuery errors. Hence, using a QUrl as the
99 message \a identifier is was inspired by the explanation of \l{error
100 handling in the XQuery language}. Because the \a identifier is
101 composed of a namespace URI and a local part, identifiers with the
102 same local part are unique. The caller is responsible for ensuring
103 that \a identifier is either a valid QUrl or a default constructed
104 QUrl.
105
106 \a sourceLocation identifies a location in a resource (i.e., file or
107 document) where the need for reporting a message was detected.
108
109 This function unconditionally calls handleMessage(), passing all
110 its parameters unmodified.
111
112 \sa {http://www.w3.org/TR/xquery/#errors}
113 */
114void QAbstractMessageHandler::message(QtMsgType type,
115 const QString &description,
116 const QUrl &identifier,
117 const QSourceLocation &sourceLocation)
118{
119 handleMessage(type, description, identifier, sourceLocation);
120}
121
122/*!
123 \fn void QAbstractMessageHandler::handleMessage(QtMsgType type,
124 const QString &description,
125 const QUrl &identifier = QUrl(),
126 const QSourceLocation &sourceLocation = QSourceLocation()) = 0
127
128 This function must be implemented by the sub-class. message() will
129 call this function, passing in its parameters, \a type,
130 \a description, \a identifier and \a sourceLocation unmodified.
131
132 This function can potentially be called from multiple threads. It's the reimplementation's
133 responsibility to ensure thread safety.
134 */
135
136QT_END_NAMESPACE
137
138

source code of qtxmlpatterns/src/xmlpatterns/api/qabstractmessagehandler.cpp