path: root/src/scripttools/debugging/qscriptenginedebuggerfrontend.cpp

/****************************************************************************
**
** Copyright (C) 2018 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtSCriptTools 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 The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/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 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qscriptenginedebuggerfrontend_p.h"
#include "qscriptdebuggerfrontend_p_p.h"
#include "qscriptdebuggerbackend_p.h"
#include "qscriptdebuggerbackend_p_p.h"
#include "qscriptdebuggerevent_p.h"
#include "qscriptdebuggercommandexecutor_p.h"
#include "qscriptdebuggerresponse_p.h"

#include <QtCore/qcoreapplication.h>
#include <QtCore/qeventloop.h>
#include <QtCore/qlist.h>
#include <QtScript/qscriptvalue.h>

QT_BEGIN_NAMESPACE

/*!
  \class QScriptEngineDebuggerFrontend
  \since 4.5
  \internal

  \brief The QScriptEngineDebuggerFrontend class provides an in-process debugger frontend.

  This type of frontend is used when the QScriptEngine being debugged
  lives in the same process as the debugger.

  Call the attachTo() function to attach to an engine.
*/

class QScriptDebuggerCommandEvent : public QEvent
{
public:
    QScriptDebuggerCommandEvent(int id, const QScriptDebuggerCommand &command)
        : QEvent(QEvent::Type(QEvent::User+3)), m_id(id), m_command(command) {}
    ~QScriptDebuggerCommandEvent() {}
    int id() const
        { return m_id; }
    const QScriptDebuggerCommand &command() const
        { return m_command; }
private:
    int m_id;
    QScriptDebuggerCommand m_command;
};

class QScriptDebuggerCommandFinishedEvent : public QEvent
{
public:
    QScriptDebuggerCommandFinishedEvent(int id, const QScriptDebuggerResponse &response)
        : QEvent(QEvent::Type(QEvent::User+4)), m_id(id), m_response(response) {}
    ~QScriptDebuggerCommandFinishedEvent() {}
    int id() const
        { return m_id; }
    const QScriptDebuggerResponse &response() const
        { return m_response; }
private:
    int m_id;
    QScriptDebuggerResponse m_response;
};

class QScriptEngineDebuggerBackendPrivate;
class QScriptEngineDebuggerBackend : public QScriptDebuggerBackend
{
public:
    QScriptEngineDebuggerBackend(QScriptEngineDebuggerFrontendPrivate *frontend);
    ~QScriptEngineDebuggerBackend();

    void processCommand(int id, const QScriptDebuggerCommand &command);
    void resume();

protected:
    void event(const QScriptDebuggerEvent &event);

private:
    Q_DECLARE_PRIVATE(QScriptEngineDebuggerBackend)
    Q_DISABLE_COPY(QScriptEngineDebuggerBackend)
};

class QScriptEngineDebuggerBackendPrivate
    : public QScriptDebuggerBackendPrivate
{
    Q_DECLARE_PUBLIC(QScriptEngineDebuggerBackend)
public:
    QScriptEngineDebuggerBackendPrivate();
    ~QScriptEngineDebuggerBackendPrivate();

    bool event(QEvent *e);

    QScriptEngineDebuggerFrontendPrivate *frontend;
    QList<QEventLoop*> eventLoopPool;
    QList<QEventLoop*> eventLoopStack;
};

class QScriptEngineDebuggerFrontendPrivate
    : public QScriptDebuggerFrontendPrivate
{
    Q_DECLARE_PUBLIC(QScriptEngineDebuggerFrontend)
public:
    QScriptEngineDebuggerFrontendPrivate();
    ~QScriptEngineDebuggerFrontendPrivate();

    void postCommandFinished(int id, const QScriptDebuggerResponse &response);
    bool event(QEvent *e);

    QScriptEngineDebuggerBackend *backend;
};

QScriptEngineDebuggerBackendPrivate::QScriptEngineDebuggerBackendPrivate()
{
    frontend = 0;
}

QScriptEngineDebuggerBackendPrivate::~QScriptEngineDebuggerBackendPrivate()
{
    eventLoopPool << eventLoopStack;
    eventLoopStack.clear();
    while (!eventLoopPool.isEmpty()) {
        QEventLoop *eventLoop = eventLoopPool.takeFirst();
        if (eventLoop->isRunning()) {
            eventLoop->quit();
            eventLoop->deleteLater();
        } else {
            delete eventLoop;
        }
    }
}

/*!
  \reimp
*/
bool QScriptEngineDebuggerBackendPrivate::event(QEvent *e)
{
    Q_Q(QScriptEngineDebuggerBackend);
    if (e->type() == QEvent::User+3) {
        QScriptDebuggerCommandEvent *ce = static_cast<QScriptDebuggerCommandEvent*>(e);
        QScriptDebuggerCommandExecutor *executor = q->commandExecutor();
        QScriptDebuggerResponse response = executor->execute(q, ce->command());
        frontend->postCommandFinished(ce->id(), response);
        return true;
    }
    return QScriptDebuggerBackendPrivate::event(e);
}

/*!
  \internal

  Creates a new QScriptEngineDebuggerBackend object for the given \a
  engine.  The back-end will forward events to the given \a frontend.
*/
QScriptEngineDebuggerBackend::QScriptEngineDebuggerBackend(
    QScriptEngineDebuggerFrontendPrivate *frontend)
    : QScriptDebuggerBackend(*new QScriptEngineDebuggerBackendPrivate)
{
    Q_D(QScriptEngineDebuggerBackend);
    d->frontend = frontend;
}

QScriptEngineDebuggerBackend::~QScriptEngineDebuggerBackend()
{
}

void QScriptEngineDebuggerBackend::processCommand(int id, const QScriptDebuggerCommand &command)
{
    Q_D(QScriptEngineDebuggerBackend);
    if (d->agent)
        d->postEvent(new QScriptDebuggerCommandEvent(id, command));
}

/*!
  \reimp
*/
void QScriptEngineDebuggerBackend::event(const QScriptDebuggerEvent &event)
{
    Q_D(QScriptEngineDebuggerBackend);
    if (d->eventLoopPool.isEmpty())
        d->eventLoopPool.append(new QEventLoop());
    QEventLoop *eventLoop = d->eventLoopPool.takeFirst();
    Q_ASSERT(!eventLoop->isRunning());
    d->eventLoopStack.prepend(eventLoop);

    d->frontend->postEvent(new QScriptDebuggerEventEvent(event));

    // Run an event loop until resume() is called.
    // This effectively stalls script execution and makes it possible
    // for the debugger to inspect the execution state in the meantime.
    eventLoop->exec();

    if (!d->eventLoopStack.isEmpty()) {
        // the event loop was quit directly (i.e. not via resume())
        d->eventLoopStack.takeFirst();
    }
    d->eventLoopPool.append(eventLoop);
    doPendingEvaluate(/*postEvent=*/false);
}

/*!
  \reimp
*/
void QScriptEngineDebuggerBackend::resume()
{
    Q_D(QScriptEngineDebuggerBackend);
    // quitting the event loops will cause event() to return (see above)
    while (!d->eventLoopStack.isEmpty()) {
        QEventLoop *eventLoop = d->eventLoopStack.takeFirst();
        if (eventLoop->isRunning())
            eventLoop->quit();
    }
}

QScriptEngineDebuggerFrontendPrivate::QScriptEngineDebuggerFrontendPrivate()
{
    backend = 0;
}

QScriptEngineDebuggerFrontendPrivate::~QScriptEngineDebuggerFrontendPrivate()
{
    delete backend;
}

void QScriptEngineDebuggerFrontendPrivate::postCommandFinished(
    int id, const QScriptDebuggerResponse &response)
{
    postEvent(new QScriptDebuggerCommandFinishedEvent(id, response));
}

/*!
  \reimp
*/
bool QScriptEngineDebuggerFrontendPrivate::event(QEvent *e)
{
    Q_Q(QScriptEngineDebuggerFrontend);
    if (e->type() == QEvent::User+4) {
        QScriptDebuggerCommandFinishedEvent *fe = static_cast<QScriptDebuggerCommandFinishedEvent*>(e);
        q->notifyCommandFinished(fe->id(), fe->response());
        return true;
    }
    return QScriptDebuggerFrontendPrivate::event(e);
}

QScriptEngineDebuggerFrontend::QScriptEngineDebuggerFrontend()
    : QScriptDebuggerFrontend(*new QScriptEngineDebuggerFrontendPrivate)
{
}

QScriptEngineDebuggerFrontend::~QScriptEngineDebuggerFrontend()
{
    detach();
}

/*!
  Attaches this front-end to the given \a engine.
*/
void QScriptEngineDebuggerFrontend::attachTo(QScriptEngine *engine)
{
    Q_D(QScriptEngineDebuggerFrontend);
    if (d->backend)
        d->backend->detach();
    else
        d->backend = new QScriptEngineDebuggerBackend(d);
    d->backend->attachTo(engine);
}

/*!
  Detaches this front-end from the current script engine.
*/
void QScriptEngineDebuggerFrontend::detach()
{
    Q_D(QScriptEngineDebuggerFrontend);
    if (d->backend)
        d->backend->detach();
}

QScriptValue QScriptEngineDebuggerFrontend::traceFunction() const
{
    Q_D(const QScriptEngineDebuggerFrontend);
    if (d->backend)
        d->backend->traceFunction();
    return QScriptValue();
}

QScriptDebuggerBackend *QScriptEngineDebuggerFrontend::backend() const
{
    Q_D(const QScriptEngineDebuggerFrontend);
    return d->backend;
}

/*!
  \internal
*/
void QScriptEngineDebuggerFrontend::processCommand(int id, const QScriptDebuggerCommand &command)
{
    Q_D(QScriptEngineDebuggerFrontend);
    Q_ASSERT(d->backend != 0);
    d->backend->processCommand(id, command);
}

QT_END_NAMESPACE