Import qlogger framework

Merge most parts of the qlogger framework from

git://gitorious.org/qtplayground/qlogger.git

The categorized logging feature is a replacement for qDebug, qWarning and
friends. With logging statements in an app/library, a developer can
turn on the statements they care about and turn off the ones they don't.

Most work for this was done by Wolfgang Beck and Lincoln Ramsay.

Task-number: QTBUG-25694
Change-Id: Ib0cdfbbf3694f86ad9ec553b2ea36f09a477cded
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/src/corelib/doc/snippets/qloggingcategory/main.cpp b/src/corelib/doc/snippets/qloggingcategory/main.cpp
new file mode 100644
index 0000000000..d6d9ae0ff3
--- /dev/null
+++ b/src/corelib/doc/snippets/qloggingcategory/main.cpp
@@ -0,0 +1,113 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QCoreApplication>
+#include <QLoggingCategory>
+
+//![1]
+// in a header
+Q_DECLARE_LOGGING_CATEGORY(QT_DRIVER_USB)
+
+// in one source file
+Q_LOGGING_CATEGORY(QT_DRIVER_USB, "qt.driver.usb")
+//![1]
+
+
+// Completely made up example, inspired by en.wikipedia.org/wiki/USB :)
+struct UsbEntry {
+    int id;
+    int classtype;
+};
+
+QDebug operator<<(QDebug &dbg, const UsbEntry &entry)
+{
+    dbg.nospace() << "" << entry.id << " (" << entry.classtype << ")";
+    return dbg.space();
+}
+
+QList<UsbEntry> usbEntries() {
+    QList<UsbEntry> entries;
+    return entries;
+}
+
+void main(int argc, char *argv[])
+{
+    QCoreApplication a(argc, argv);
+
+//![2]
+    // don't run the expensive code if the string won't print
+    if (QT_DRIVER_USB().isEnabled<QtDebugMsg>()) {
+        QStringList items;
+        foreach (const UsbEntry &entry, usbEntries())
+            items << QString("%1 (%2)").arg(entry.id, entry.classtype);
+        qCDebug(QT_DRIVER_USB) << "devices: " << items;
+    }
+//![2]
+
+//![3]
+    // usbEntries() will only be called if QT_DRIVER_USB category is enabled
+    qCDebug(QT_DRIVER_USB) << "devices: " << usbEntries();
+//![3]
+
+    {
+//![10]
+    QLoggingCategory category("qt.driver.usb");
+    qCDebug(category) << "a debug message";
+//![10]
+    }
+
+    {
+//![11]
+    QLoggingCategory category("qt.driver.usb");
+    qCWarning(category) << "a warning message";
+//![11]
+    }
+
+    {
+//![12]
+    QLoggingCategory category("qt.driver.usb");
+    qCCritical(category) << "a critical message";
+//![12]
+    }
+}
+
+//![20]
+void myCategoryFilter(QLoggingCategory *);
+//![20]