Add qFormatLogMessage()

Export the former qMessageFormatString() as qFormatLogMessage(). This
allows custom message handlers to format their messages just like the
default message handler, taking qSetMessagePattern() /
QT_MESSAGE_PATTERN into account.

The method should arguably not add the '\n' at the end, which a follow
up commit will fix.

Change-Id: Ib2a9cfda91473df079daf03bf3197e6ac63e013e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>

src/corelib/global/qlogging.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Copyright (C) 2014 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: http://www.qt-project.org/legal
 **
@@ -1052,10 +1052,20 @@ static void slog2_default_handler(QtMsgType msgType, const char *message)
 Q_GLOBAL_STATIC(QMessagePattern, qMessagePattern)
 
 /*!
-    \internal
-*/
-Q_CORE_EXPORT QString qMessageFormatString(QtMsgType type, const QMessageLogContext &context,
-                                              const QString &str)
+    \relates <QtGlobal>
+    \since 5.4
+
+    Generates a formatted string out of the \a type, \a context, \a str arguments.
+
+    qFormatLogMessage returns a QString that is formatted according to the current message pattern.
+    It can be used by custom message handlers to format output similar to Qt's default message
+    handler.
+
+    The function is thread-safe.
+
+    \sa qInstallMessageHandler(), qSetMessagePattern()
+ */
+QString qFormatLogMessage(QtMsgType type, const QMessageLogContext &context, const QString &str)
 {
     QString message;
 
@@ -1278,7 +1288,7 @@ static void qDefaultMessageHandler(QtMsgType type, const QMessageLogContext &con
         bool toConsole;
     };
 
-    QString logMessage = qMessageFormatString(type, context, buf);
+    QString logMessage = qFormatLogMessage(type, context, buf);
 
 #if defined(Q_OS_WIN) && defined(QT_BUILD_CORE_LIB)
     if (!qWinLogToStderr()) {
@@ -1583,7 +1593,7 @@ void qErrnoWarning(int code, const char *msg, ...)
     environment variable; if both qSetMessagePattern() is called and QT_MESSAGE_PATTERN is
     set, the environment variable takes precedence.
 
-    qSetMessagePattern() has no effect if a custom message handler is installed.
+    Custom message handlers can use qFormatLogMessage() to take \a pattern into account.
 
     \sa qInstallMessageHandler(), {Debugging Techniques}
  */

src/corelib/global/qlogging.h

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -167,6 +167,8 @@ typedef void (*QtMessageHandler)(QtMsgType, const QMessageLogContext &, const QS
 Q_CORE_EXPORT QtMessageHandler qInstallMessageHandler(QtMessageHandler);
 
 Q_CORE_EXPORT void qSetMessagePattern(const QString &messagePattern);
+Q_CORE_EXPORT QString qFormatLogMessage(QtMsgType type, const QMessageLogContext &context,
+                                        const QString &buf);
 
 QT_END_NAMESPACE
 #endif // QLOGGING_H

src/testlib/qtestlog.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtTest module of the Qt Toolkit.
@@ -59,8 +59,6 @@
 
 QT_BEGIN_NAMESPACE
 
-Q_CORE_EXPORT QString qMessageFormatString(QtMsgType type, const QMessageLogContext &context, const QString& msg);
-
 static void saveCoverageTool(const char * appname, bool testfailed, bool installedTestCoverage)
 {
 #ifdef __COVERAGESCANNER__
@@ -287,7 +285,7 @@ namespace QTest {
             // the message is expected, so just swallow it.
             return;
 
-        QString msg = qMessageFormatString(type, context, message);
+        QString msg = qFormatLogMessage(type, context, message);
         msg.chop(1); // remove trailing newline
 
         if (type != QtFatalMsg) {

tests/auto/corelib/global/qlogging/tst_qlogging.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Copyright (C) 2014 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: http://www.qt-project.org/legal
 **
@@ -68,6 +68,9 @@ private slots:
     void qMessagePattern();
     void setMessagePattern();
 
+    void formatLogMessage_data();
+    void formatLogMessage();
+
 private:
     QString m_appDir;
     QStringList m_baseEnvironment;
@@ -803,6 +806,63 @@ void tst_qmessagehandler::setMessagePattern()
 #endif // !QT_NO_PROCESS
 }
 
+Q_DECLARE_METATYPE(QtMsgType)
+
+void tst_qmessagehandler::formatLogMessage_data()
+{
+    QTest::addColumn<QString>("pattern");
+    QTest::addColumn<QString>("result");
+
+    QTest::addColumn<QtMsgType>("type");
+    QTest::addColumn<QByteArray>("file");
+    QTest::addColumn<int>("line");
+    QTest::addColumn<QByteArray>("function");
+    QTest::addColumn<QByteArray>("category");
+    QTest::addColumn<QString>("message");
+
+#define BA QByteArrayLiteral
+
+    QTest::newRow("basic") << "%{type} %{file} %{line} %{function} %{message}"
+                           << "debug main.cpp 1 func msg\n"
+                           << QtDebugMsg << BA("main.cpp") << 1 << BA("func") << BA("") << "msg";
+
+    // test the if conditions
+    QString format = "[%{if-debug}D%{endif}%{if-warning}W%{endif}%{if-critical}C%{endif}%{if-fatal}F%{endif}] %{if-category}%{category}: %{endif}%{message}";
+    QTest::newRow("if-debug")
+            << format << "[D] msg\n"
+            << QtDebugMsg << BA("") << 0 << BA("func") << QByteArray() << "msg";
+    QTest::newRow("if_warning")
+            << format << "[W] msg\n"
+            << QtWarningMsg << BA("") << 0 << BA("func") << QByteArray() << "msg";
+    QTest::newRow("if_critical")
+            << format << "[C] msg\n"
+            << QtCriticalMsg << BA("") << 0 << BA("func") << QByteArray() << "msg";
+    QTest::newRow("if_fatal")
+            << format << "[F] msg\n"
+            << QtFatalMsg << BA("") << 0 << BA("func") << QByteArray() << "msg";
+    QTest::newRow("if_cat")
+            << format << "[F] cat: msg\n"
+            << QtFatalMsg << BA("") << 0 << BA("func") << BA("cat") << "msg";
+}
+
+void tst_qmessagehandler::formatLogMessage()
+{
+    QFETCH(QString, pattern);
+    QFETCH(QString, result);
+
+    QFETCH(QtMsgType, type);
+    QFETCH(QByteArray, file);
+    QFETCH(int, line);
+    QFETCH(QByteArray, function);
+    QFETCH(QByteArray, category);
+    QFETCH(QString, message);
+
+    qSetMessagePattern(pattern);
+    QMessageLogContext ctxt(file, line, function, category.isEmpty() ? 0 : category.data());
+    QString r = qFormatLogMessage(type, ctxt, message);
+    QCOMPARE(r, result);
+}
+
 
 QTEST_MAIN(tst_qmessagehandler)
 #include "tst_qlogging.moc"