Restructure sources and assimilate to Qt module structure.

This module can hopefully be done in time for 5.3. This commit changes
the source structure and QMake files to adapt to typical Qt modules.

With this in place, we can now use QT += webchannel in qmake files to
link against the pure Qt/C++ QtWebChannel library.

The QML plugin is separated from it and can be loaded optionally, if
the quick module could be found. Also added is now a qmlplugindump
for tooling integration. Note that the Qt.labs namespace is removed.

The test file structure is also adapted to how its done in the
QtDeclarative module.

Note that this setup apparently does not support to run tests without
running make install first.

Change-Id: I1c15d72e7ab5f525d5a6f651f4e965ef86bc17bd
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 278 insertions, 0 deletions

diff --git a/src/webchannel/signalhandler_p.h b/src/webchannel/signalhandler_p.h
new file mode 100644
index 0000000..2613f92
--- /dev/null
+++ b/src/webchannel/signalhandler_p.h
@@ -0,0 +1,278 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2013 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
+** Contact: http://www.qt-project.org/legal
+*
+** This file is part of the QtWebChannel 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SIGNALHANDLER_H
+#define SIGNALHANDLER_H
+
+#include <QObject>
+#include <QHash>
+#include <QVector>
+#include <QMetaMethod>
+#include <QDebug>
+
+/**
+ * The signal handler is similar to QSignalSpy, but geared towards the usecase of the web channel.
+ *
+ * It allows connecting to any number of signals of arbitrary objects and forwards the signal
+ * invocations to the Receiver by calling its signalEmitted function, which takes the object,
+ * signal index and a QVariantList of arguments.
+ */
+template<class Receiver>
+class SignalHandler : public QObject
+{
+public:
+    SignalHandler(Receiver *receiver, QObject *parent = 0)
+        : QObject(parent)
+        , m_receiver(receiver)
+    {
+    }
+
+    /**
+     * Connect to a signal of @p object identified by @p signalIndex.
+     *
+     * If the handler is already connected to the signal, an internal counter is increased,
+     * i.e. the handler never connects multiple times to the same signal.
+     */
+    void connectTo(const QObject *object, const int signalIndex);
+
+    /**
+     * Decrease the connection counter for the connection to the given signal.
+     *
+     * When the counter drops to zero, the connection is disconnected.
+     */
+    void disconnectFrom(const QObject *object, const int signalIndex);
+
+    /**
+     * @internal
+     *
+     * Custom implementation of qt_metacall which calls dispatch() for connected signals.
+     */
+    int qt_metacall(QMetaObject::Call call, int methodId, void **args) Q_DECL_OVERRIDE;
+
+    /**
+     * Reset all connections, useful for benchmarks.
+     */
+    void clear();
+
+private:
+    /**
+     * Exctract the arguments of a signal call and pass them to the receiver.
+     *
+     * The @p argumentData is converted to a QVariantList and then passed to the receiver's
+     * signalEmitted method.
+     */
+    void dispatch(const QObject *object, const int signalIdx, void **argumentData);
+
+    Receiver *m_receiver;
+
+    // maps meta object -> signalIndex -> list of arguments
+    // NOTE: This data is "leaked" on disconnect until deletion of the handler, is this a problem?
+    typedef QVector<int> ArgumentTypeList;
+    typedef QHash<int, ArgumentTypeList> SignalArgumentHash;
+    QHash<const QMetaObject *, SignalArgumentHash > m_signalArgumentTypes;
+
+    /*
+     * Tracks how many connections are active to object signals.
+     *
+     * Maps object -> signalIndex -> pair of connection and number of connections
+     *
+     * Note that the handler is connected to the signal only once, whereas clients
+     * may have connected multiple times.
+     *
+     * TODO: Move more of this logic to the HTML client side, esp. the connection counting.
+     */
+    typedef QPair<QMetaObject::Connection, int> ConnectionPair;
+    typedef QHash<int, ConnectionPair> SignalConnectionHash;
+    typedef QHash<const QObject*, SignalConnectionHash> ConnectionHash;
+    ConnectionHash m_connectionsCounter;
+};
+
+/**
+ * Find and return the signal of index @p signalIndex in the meta object of @p object and return it.
+ *
+ * The return value is also verified to ensure it is a signal.
+ */
+QMetaMethod findSignal(const QMetaObject *metaObject, const int signalIndex)
+{
+    QMetaMethod signal = metaObject->method(signalIndex);
+    if (!signal.isValid()) {
+        qWarning("Cannot find signal with index %d of object %s", signalIndex, metaObject->className());
+        return QMetaMethod();
+    }
+    Q_ASSERT(signal.methodType() == QMetaMethod::Signal);
+    return signal;
+}
+
+template<class Receiver>
+void SignalHandler<Receiver>::connectTo(const QObject *object, const int signalIndex)
+{
+    const QMetaObject *metaObject = object->metaObject();
+    const QMetaMethod &signal = findSignal(metaObject, signalIndex);
+    if (!signal.isValid()) {
+        return;
+    }
+
+    ConnectionPair &connectionCounter = m_connectionsCounter[object][signalIndex];
+    if (connectionCounter.first) {
+        // increase connection counter if already connected
+        ++connectionCounter.second;
+        return;
+    } // otherwise not yet connected, do so now
+
+    const int memberOffset = QObject::staticMetaObject.methodCount();
+    QMetaObject::Connection connection = QMetaObject::connect(object, signal.methodIndex(), this, memberOffset, Qt::DirectConnection, 0);
+    if (!connection) {
+        qWarning() << "SignalHandler: QMetaObject::connect returned false. Unable to connect to" << object << signal.name() << signal.methodSignature();
+        return;
+    }
+    connectionCounter.first = connection;
+    connectionCounter.second = 1;
+
+    if (!m_signalArgumentTypes.value(metaObject).contains(signal.methodIndex())) {
+        // find the type ids of the signal parameters, see also QSignalSpy::initArgs
+        QVector<int> args;
+        args.reserve(signal.parameterCount());
+        for (int i = 0; i < signal.parameterCount(); ++i) {
+            int tp = signal.parameterType(i);
+            if (tp == QMetaType::UnknownType && object) {
+                void *argv[] = { &tp, &i };
+                QMetaObject::metacall(const_cast<QObject *>(object),
+                                    QMetaObject::RegisterMethodArgumentMetaType,
+                                    signal.methodIndex(), argv);
+                if (tp == -1) {
+                    tp = QMetaType::UnknownType;
+                }
+            }
+            if (tp == QMetaType::UnknownType) {
+                Q_ASSERT(tp != QMetaType::Void); // void parameter => metaobject is corrupt
+                qWarning("Don't know how to handle '%s', use qRegisterMetaType to register it.",
+                        signal.parameterNames().at(i).constData());
+            }
+            args << tp;
+        }
+
+        m_signalArgumentTypes[metaObject][signal.methodIndex()] = args;
+    }
+}
+
+template<class Receiver>
+void SignalHandler<Receiver>::dispatch(const QObject *object, const int signalIdx, void **argumentData)
+{
+    Q_ASSERT(m_signalArgumentTypes.contains(object->metaObject()));
+    const QHash<int, QVector<int> > &objectSignalArgumentTypes = m_signalArgumentTypes.value(object->metaObject());
+    QHash<int, QVector<int> >::const_iterator signalIt = objectSignalArgumentTypes.constFind(signalIdx);
+    if (signalIt == objectSignalArgumentTypes.constEnd()) {
+        // not connected to this signal, skip
+        return;
+    }
+    const QVector<int> &argumentTypes = *signalIt;
+    QVariantList arguments;
+    arguments.reserve(argumentTypes.count());
+    // TODO: basic overload resolution based on number of arguments?
+    for (int i = 0; i < argumentTypes.count(); ++i) {
+        const QMetaType::Type type = static_cast<QMetaType::Type>(argumentTypes.at(i));
+        QVariant arg;
+        if (type == QMetaType::QVariant) {
+            arg = *reinterpret_cast<QVariant *>(argumentData[i + 1]);
+        } else {
+            arg = QVariant(type, argumentData[i + 1]);
+        }
+        arguments.append(arg);
+    }
+    m_receiver->signalEmitted(object, signalIdx, arguments);
+}
+
+template<class Receiver>
+void SignalHandler<Receiver>::disconnectFrom(const QObject *object, const int signalIndex)
+{
+    Q_ASSERT(m_connectionsCounter.value(object).contains(signalIndex));
+    ConnectionPair &connection = m_connectionsCounter[object][signalIndex];
+    --connection.second;
+    if (!connection.second || !connection.first) {
+        QObject::disconnect(connection.first);
+        m_connectionsCounter[object].remove(signalIndex);
+        if (m_connectionsCounter[object].isEmpty()) {
+            m_connectionsCounter.remove(object);
+        }
+    }
+}
+
+template<class Receiver>
+int SignalHandler<Receiver>::qt_metacall(QMetaObject::Call call, int methodId, void **args)
+{
+    methodId = QObject::qt_metacall(call, methodId, args);
+    if (methodId < 0)
+        return methodId;
+
+    if (call == QMetaObject::InvokeMetaMethod) {
+        if (methodId == 0) {
+            Q_ASSERT(sender());
+            Q_ASSERT(senderSignalIndex() != -1);
+            dispatch(sender(), senderSignalIndex(), args);
+            static const int destroyedIndex = metaObject()->indexOfSignal("destroyed(QObject*)");
+            if (senderSignalIndex() == destroyedIndex) {
+                ConnectionHash::iterator it = m_connectionsCounter.find(sender());
+                Q_ASSERT(it != m_connectionsCounter.end());
+                foreach (const ConnectionPair &connection, *it) {
+                    QObject::disconnect(connection.first);
+                }
+                m_connectionsCounter.erase(it);
+            }
+        }
+        --methodId;
+    }
+    return methodId;
+}
+
+template<class Receiver>
+void SignalHandler<Receiver>::clear()
+{
+    foreach (const SignalConnectionHash &connections, m_connectionsCounter) {
+        foreach (const ConnectionPair &connection, connections) {
+            QObject::disconnect(connection.first);
+        }
+    }
+    m_connectionsCounter.clear();
+    m_signalArgumentTypes.clear();
+}
+
+#endif // SIGNALHANDLER_H