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, 352 insertions, 0 deletions

diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
new file mode 100644
index 0000000000..562cf25964
--- /dev/null
+++ b/src/corelib/io/qloggingcategory.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2013 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.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qloggingcategory.h"
+#include "qloggingcategory_p.h"
+#include "qloggingregistry_p.h"
+
+QT_BEGIN_NAMESPACE
+
+const char qtDefaultCategoryName[] = "default";
+
+Q_GLOBAL_STATIC_WITH_ARGS(QLoggingCategory, qtDefaultCategory,
+                          (qtDefaultCategoryName))
+
+/*!
+    \class QLoggingCategory
+    \inmodule QtCore
+    \since 5.2
+
+    \brief A category, or 'area' in the logging infrastructure.
+
+    QLoggingCategory represents a certain logging category - identified
+    by a string - at runtime. Whether a category should be actually logged or
+    not can be checked with the \l isEnabled() methods.
+
+    \section1 Creating category objects
+
+    Qt provides the \l Q_LOGGING_CATEGORY(), Q_DECLARE_LOGGING_CATEGORY() macros
+    to conveniently create static QLoggingCategory objects on the heap:
+
+    \snippet qloggingcategory/main.cpp 1
+
+    \section1 Checking category configuration
+
+    QLoggingCategory provides two isEnabled methods, a template one and a
+    non-template one, for checking whether the current category is enabled.
+    The template version checks for the most common case that no special rules
+    are applied in inline code, and should be preferred:
+
+    \snippet qloggingcategory/main.cpp 2
+
+    Note that qCDebug() prevents arguments from being evaluated
+    if the string won't print, so calling isEnabled explicitly is not needed:
+    \l isEnabled().
+
+    \snippet qloggingcategory/main.cpp 3
+
+    \section1 Default configuration
+
+    In the default configuration \l isEnabled() will return true for all
+    \l QtMsgType types except QtDebugMsg: QtDebugMsg is only active by default
+    for the \c "default" category.
+
+    \section1 Changing configuration
+
+    The default configuration can be changed by calling \l setEnabled(). However,
+    this only affects the current category object, not e.g. another object for the
+    same category name. Use either \l setFilterRules() or \l installFilter() to
+    configure categories globally.
+*/
+
+/*!
+    Constructs a QLoggingCategory object with the provided \a category name.
+    The object becomes the local identifier for the category.
+
+    If \a category is \c{0}, the category name is changed to \c{"default"}.
+*/
+QLoggingCategory::QLoggingCategory(const char *category)
+    : name(0),
+      enabledDebug(false),
+      enabledWarning(true),
+      enabledCritical(true)
+{
+    bool isDefaultCategory
+            = (category == 0) || (strcmp(category, qtDefaultCategoryName) == 0);
+
+    if (isDefaultCategory) {
+        // normalize default category names, so that we can just do
+        // pointer comparison in QLoggingRegistry::updateCategory
+        name = qtDefaultCategoryName;
+        enabledDebug = true;
+    } else {
+        name = category;
+    }
+
+    if (QLoggingRegistry *reg = QLoggingRegistry::instance())
+        reg->registerCategory(this);}
+
+/*!
+    Destructs a QLoggingCategory object
+*/
+QLoggingCategory::~QLoggingCategory()
+{
+    if (QLoggingRegistry *reg = QLoggingRegistry::instance())
+        reg->unregisterCategory(this);
+}
+
+/*!
+   \fn const char *QLoggingCategory::categoryName() const
+
+    Returns the name of the category.
+*/
+
+/*!
+    \fn bool QLoggingCategory::isEnabled() const
+
+    Returns true if a message of the template \c QtMsgType argument should be
+    shown. Returns false otherwise.
+
+    \note The qCDebug, qCWarning, qCCritical macros already do this check before
+    executing any code. However, calling this method may be useful to avoid
+    expensive generation of data that is only used for debug output.
+*/
+
+/*!
+    Returns true if a message of type \a msgtype for the category should be
+    shown. Returns false otherwise.
+
+    \note The templated, inline version of this method, \l isEnabled(), is
+    optimized for the common case that no configuration is set, and should
+    generally be preferred.
+*/
+bool QLoggingCategory::isEnabled(QtMsgType msgtype) const
+{
+    switch (msgtype) {
+    case QtDebugMsg: return enabledDebug;
+    case QtWarningMsg: return enabledWarning;
+    case QtCriticalMsg: return enabledCritical;
+    case QtFatalMsg: return true;
+    default: break;
+    }
+    return false;
+}
+
+/*!
+    Changes the type \a type for the category to \a enable.
+
+    Changes only affect the current QLoggingCategory object, and won't
+    change e.g. the settings of another objects for the same category name.
+
+    \note QtFatalMsg cannot be changed. It will always return true.
+*/
+void QLoggingCategory::setEnabled(QtMsgType type, bool enable)
+{
+    switch (type) {
+    case QtDebugMsg: enabledDebug = enable; break;
+    case QtWarningMsg: enabledWarning = enable; break;
+    case QtCriticalMsg: enabledCritical = enable; break;
+    case QtFatalMsg:
+    default: break;
+    }
+}
+
+/*!
+    \fn QLoggingCategory &QLoggingCategory::operator()()
+
+    Returns the object itself. This allows both a QLoggingCategory variable, and
+    a factory method returning a QLoggingCategory, to be used in qCDebug(),
+    qCWarning(), qCCritial() macros.
+ */
+
+/*!
+    Returns the category "default" that is used e.g. by qDebug(), qWarning(),
+    qCritical(), qFatal().
+ */
+QLoggingCategory &QLoggingCategory::defaultCategory()
+{
+    return *qtDefaultCategory();
+}
+
+/*!
+    \typedef QLoggingCategory::CategoryFilter
+
+    This is a typedef for a pointer to a function with the following
+    signature:
+
+    \snippet qloggingcategory/main.cpp 20
+
+    A function with this signature can be installed with \l installFilter().
+*/
+
+/*!
+    Installs a function \a filter that is used to determine which categories
+    and message types should be enabled. Returns a pointer to the previous
+    installed filter.
+
+    Every QLoggingCategory object created is passed to the filter, and the
+    filter is free to change the respective category configuration with
+    \l setEnabled().
+
+    An alternative way of configuring the default filter is via
+    \l setFilterRules().
+ */
+QLoggingCategory::CategoryFilter
+QLoggingCategory::installFilter(QLoggingCategory::CategoryFilter filter)
+{
+    return QLoggingRegistry::instance()->installFilter(filter);
+}
+
+
+/*!
+    Configures which categories and message types should be enabled through a
+    a set of \a rules.
+
+    Each line in \a rules must have the format
+
+    \code
+    <category>[.<type>] = true|false
+    \endcode
+
+    where \c <category> is the name of the category, potentially with \c{*} as a
+    wildcard symbol at the start and/or the end. The optional \c <type> must
+    be either \c debug, \c warning, or \c critical.
+
+    The rules might be ignored if a custom category filter is installed with
+    \l installFilter().
+*/
+void QLoggingCategory::setFilterRules(const QString &rules)
+{
+    QLoggingRegistry::instance()->rulesParser.setRules(rules);
+}
+
+/*!
+    \macro qCDebug(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for debug messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for debug output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 10
+
+    \note Arguments are not processed if debug output for the category is not
+    enabled, so do not rely on any side effects.
+
+    \sa qDebug()
+*/
+
+/*!
+    \macro qCWarning(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for warning messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for warning output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 11
+
+    \note Arguments are not processed if warning output for the category is not
+    enabled, so do not rely on any side effects.
+
+    \sa qWarning()
+*/
+
+/*!
+    \macro qCCritical(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for critical messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for critical output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 12
+
+    \note Arguments are not processed if critical output for the category is not
+    enabled, so do not reply on any side effects.
+
+    \sa qCritical()
+*/
+
+/*!
+    \macro Q_DECLARE_LOGGING_CATEGORY(name)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Declares a logging category \a name. The macro can be used to declare
+    a common logging category shared in different parts of the program.
+
+    This macro must be used outside of a class or method.
+*/
+
+/*!
+    \macro Q_LOGGING_CATEGORY(name, string)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Defines a logging category \a name, and makes it configurable under the
+    \a string identifier.
+
+    Only one translation unit in a library or executable can define a category
+    with a specific name.
+
+    This macro must be used outside of a class or method.
+*/
+
+QT_END_NAMESPACE