QmlDebug: Add V4 debug client from tst_qqmldebugjs.cpp

This is useful for implementing additional V4 debug clients.

Along the way, we also drop the dependency on QML by using the JSON API
from QtCore for JSON manipulation.

Task-number: QTBUG-66504
Change-Id: Ib51e8e97b030a49fe8185ad5354d1cca63efef4a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

4 files changed, 784 insertions, 2 deletions

diff --git a/src/qmldebug/qmldebug.pro b/src/qmldebug/qmldebug.pro
index 0807482d23..42b73e5711 100644
--- a/src/qmldebug/qmldebug.pro
+++ b/src/qmldebug/qmldebug.pro
@@ -14,7 +14,8 @@ SOURCES += \
     qqmlprofilerevent.cpp \
     qqmlprofilereventlocation.cpp \
     qqmlprofilereventtype.cpp \
-    qqmlprofilertypedevent.cpp
+    qqmlprofilertypedevent.cpp \
+    qv4debugclient.cpp
 
 HEADERS += \
     qqmldebugclient_p.h \
@@ -32,4 +33,6 @@ HEADERS += \
     qqmlprofilereventreceiver_p.h \
     qqmlprofilereventtype_p.h \
     qqmlprofilertypedevent_p.h \
-    qqmlprofilerclientdefinitions_p.h
+    qqmlprofilerclientdefinitions_p.h \
+    qv4debugclient_p.h \
+    qv4debugclient_p_p.h
diff --git a/src/qmldebug/qv4debugclient.cpp b/src/qmldebug/qv4debugclient.cpp
new file mode 100644
index 0000000000..76c2f1ebea
--- /dev/null
+++ b/src/qmldebug/qv4debugclient.cpp
@@ -0,0 +1,578 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml 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 "qv4debugclient_p.h"
+#include "qv4debugclient_p_p.h"
+#include "qqmldebugconnection_p.h"
+
+#include <private/qpacket_p.h>
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonValue>
+#include <QJsonArray>
+
+QT_BEGIN_NAMESPACE
+
+const char *V8REQUEST = "v8request";
+const char *V8MESSAGE = "v8message";
+const char *SEQ = "seq";
+const char *TYPE = "type";
+const char *COMMAND = "command";
+const char *ARGUMENTS = "arguments";
+const char *STEPACTION = "stepaction";
+const char *STEPCOUNT = "stepcount";
+const char *EXPRESSION = "expression";
+const char *FRAME = "frame";
+const char *CONTEXT = "context";
+const char *GLOBAL = "global";
+const char *DISABLEBREAK = "disable_break";
+const char *HANDLES = "handles";
+const char *INCLUDESOURCE = "includeSource";
+const char *FROMFRAME = "fromFrame";
+const char *TOFRAME = "toFrame";
+const char *BOTTOM = "bottom";
+const char *NUMBER = "number";
+const char *FRAMENUMBER = "frameNumber";
+const char *TYPES = "types";
+const char *IDS = "ids";
+const char *FILTER = "filter";
+const char *FROMLINE = "fromLine";
+const char *TOLINE = "toLine";
+const char *TARGET = "target";
+const char *LINE = "line";
+const char *COLUMN = "column";
+const char *ENABLED = "enabled";
+const char *CONDITION = "condition";
+const char *IGNORECOUNT = "ignoreCount";
+const char *BREAKPOINT = "breakpoint";
+const char *FLAGS = "flags";
+
+const char *CONTINEDEBUGGING = "continue";
+const char *EVALUATE = "evaluate";
+const char *LOOKUP = "lookup";
+const char *BACKTRACE = "backtrace";
+const char *SCOPE = "scope";
+const char *SCOPES = "scopes";
+const char *SCRIPTS = "scripts";
+const char *SOURCE = "source";
+const char *SETBREAKPOINT = "setbreakpoint";
+const char *CLEARBREAKPOINT = "clearbreakpoint";
+const char *CHANGEBREAKPOINT = "changebreakpoint";
+const char *SETEXCEPTIONBREAK = "setexceptionbreak";
+const char *VERSION = "version";
+const char *DISCONNECT = "disconnect";
+const char *GARBAGECOLLECTOR = "gc";
+
+const char *CONNECT = "connect";
+const char *INTERRUPT = "interrupt";
+
+const char *REQUEST = "request";
+const char *IN = "in";
+const char *NEXT = "next";
+const char *OUT = "out";
+
+const char *SCRIPT = "script";
+const char *SCRIPTREGEXP = "scriptRegExp";
+const char *EVENT = "event";
+
+const char *ALL = "all";
+const char *UNCAUGHT = "uncaught";
+
+#define VARIANTMAPINIT \
+    Q_D(QV4DebugClient); \
+    QJsonObject jsonVal; \
+    jsonVal.insert(QLatin1String(SEQ), d->seq++); \
+    jsonVal.insert(QLatin1String(TYPE), QLatin1String(REQUEST));
+
+QV4DebugClient::QV4DebugClient(QQmlDebugConnection *connection)
+    : QQmlDebugClient(*new QV4DebugClientPrivate(connection))
+{
+    QObject::connect(this, &QQmlDebugClient::stateChanged,
+                     this, [this](State state) { d_func()->onStateChanged(state); });
+}
+
+QV4DebugClientPrivate::QV4DebugClientPrivate(QQmlDebugConnection *connection) :
+    QQmlDebugClientPrivate(QLatin1String("V8Debugger"), connection)
+{
+}
+
+void QV4DebugClient::connect()
+{
+    Q_D(QV4DebugClient);
+    d->sendMessage(CONNECT);
+}
+
+void QV4DebugClient::interrupt()
+{
+    Q_D(QV4DebugClient);
+    d->sendMessage(INTERRUPT);
+}
+
+void QV4DebugClient::continueDebugging(StepAction action)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "continue",
+    //      "arguments" : { "stepaction" : <"in", "next" or "out">,
+    //                      "stepcount"  : <number of steps (default 1)>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(CONTINEDEBUGGING));
+
+    if (action != Continue) {
+        QJsonObject args;
+        switch (action) {
+        case In:
+            args.insert(QLatin1String(STEPACTION), QLatin1String(IN));
+            break;
+        case Out:
+            args.insert(QLatin1String(STEPACTION), QLatin1String(OUT));
+            break;
+        case Next:
+            args.insert(QLatin1String(STEPACTION), QLatin1String(NEXT));
+            break;
+        default:
+            break;
+        }
+        jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    }
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::evaluate(const QString &expr, int frame, int context)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "evaluate",
+    //      "arguments" : { "expression"    : <expression to evaluate>,
+    //                      "frame"         : <number>,
+    //                      "context"       : <object ID>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(EVALUATE));
+
+    QJsonObject args;
+    args.insert(QLatin1String(EXPRESSION), expr);
+
+    if (frame != -1)
+        args.insert(QLatin1String(FRAME), frame);
+
+    if (context != -1)
+        args.insert(QLatin1String(CONTEXT), context);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::lookup(const QList<int> &handles, bool includeSource)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "lookup",
+    //      "arguments" : { "handles"       : <array of handles>,
+    //                      "includeSource" : <boolean indicating whether the source will be included when script objects are returned>,
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND),(QLatin1String(LOOKUP)));
+
+    QJsonObject args;
+    QJsonArray array;
+
+    for (int handle : handles)
+        array.append(handle);
+
+    args.insert(QLatin1String(HANDLES), array);
+
+    if (includeSource)
+        args.insert(QLatin1String(INCLUDESOURCE), includeSource);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::backtrace(int fromFrame, int toFrame, bool bottom)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "backtrace",
+    //      "arguments" : { "fromFrame" : <number>
+    //                      "toFrame" : <number>
+    //                      "bottom" : <boolean, set to true if the bottom of the stack is requested>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(BACKTRACE));
+
+    QJsonObject args;
+
+    if (fromFrame != -1)
+        args.insert(QLatin1String(FROMFRAME), fromFrame);
+
+    if (toFrame != -1)
+        args.insert(QLatin1String(TOFRAME), toFrame);
+
+    if (bottom)
+        args.insert(QLatin1String(BOTTOM), bottom);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::frame(int number)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "frame",
+    //      "arguments" : { "number" : <frame number>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(FRAME));
+
+    if (number != -1) {
+        QJsonObject args;
+        args.insert(QLatin1String(NUMBER), number);
+        jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    }
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::scope(int number, int frameNumber)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "scope",
+    //      "arguments" : { "number" : <scope number>
+    //                      "frameNumber" : <frame number, optional uses selected frame if missing>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(SCOPE));
+
+    if (number != -1) {
+        QJsonObject args;
+        args.insert(QLatin1String(NUMBER), number);
+
+        if (frameNumber != -1)
+            args.insert(QLatin1String(FRAMENUMBER), frameNumber);
+
+        jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    }
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::scripts(int types, const QList<int> &ids, bool includeSource)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "scripts",
+    //      "arguments" : { "types"         : <types of scripts to retrieve
+    //                                           set bit 0 for native scripts
+    //                                           set bit 1 for extension scripts
+    //                                           set bit 2 for normal scripts
+    //                                         (default is 4 for normal scripts)>
+    //                      "ids"           : <array of id's of scripts to return. If this is not specified all scripts are requrned>
+    //                      "includeSource" : <boolean indicating whether the source code should be included for the scripts returned>
+    //                      "filter"        : <string or number: filter string or script id.
+    //                                         If a number is specified, then only the script with the same number as its script id will be retrieved.
+    //                                         If a string is specified, then only scripts whose names contain the filter string will be retrieved.>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(SCRIPTS));
+
+    QJsonObject args;
+    args.insert(QLatin1String(TYPES), types);
+
+    if (ids.count()) {
+        QJsonArray array;
+        for (int id : ids)
+            array.append(id);
+
+        args.insert(QLatin1String(IDS), array);
+    }
+
+    if (includeSource)
+        args.insert(QLatin1String(INCLUDESOURCE), includeSource);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::setBreakpoint(const QString &target, int line, int column, bool enabled,
+                                   const QString &condition, int ignoreCount)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "setbreakpoint",
+    //      "arguments" : { "type"        : "scriptRegExp"
+    //                      "target"      : <function expression or script identification>
+    //                      "line"        : <line in script or function>
+    //                      "column"      : <character position within the line>
+    //                      "enabled"     : <initial enabled state. True or false, default is true>
+    //                      "condition"   : <string with break point condition>
+    //                      "ignoreCount" : <number specifying the number of break point hits to ignore, default value is 0>
+    //                    }
+    //    }
+
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(SETBREAKPOINT));
+
+    QJsonObject args;
+
+    args.insert(QLatin1String(TYPE), QLatin1String(SCRIPTREGEXP));
+    args.insert(QLatin1String(TARGET), target);
+
+    if (line != -1)
+        args.insert(QLatin1String(LINE), line);
+
+    if (column != -1)
+        args.insert(QLatin1String(COLUMN), column);
+
+    args.insert(QLatin1String(ENABLED), enabled);
+
+    if (!condition.isEmpty())
+        args.insert(QLatin1String(CONDITION), condition);
+
+    if (ignoreCount != -1)
+        args.insert(QLatin1String(IGNORECOUNT), ignoreCount);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS),args);
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::clearBreakpoint(int breakpoint)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "clearbreakpoint",
+    //      "arguments" : { "breakpoint" : <number of the break point to clear>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(CLEARBREAKPOINT));
+
+    QJsonObject args;
+    args.insert(QLatin1String(BREAKPOINT), breakpoint);
+    jsonVal.insert(QLatin1String(ARGUMENTS),args);
+
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::changeBreakpoint(int breakpoint, bool enabled)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "changebreakpoint",
+    //      "arguments" : { "breakpoint" : <number of the break point to change>
+    //                      "enabled" : <bool: enables the break type if true, disables if false>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(CHANGEBREAKPOINT));
+
+    QJsonObject args;
+    args.insert(QLatin1String(BREAKPOINT), breakpoint);
+    args.insert(QLatin1String(ENABLED), enabled);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::setExceptionBreak(Exception type, bool enabled)
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "setexceptionbreak",
+    //      "arguments" : { "type"    : <string: "all", or "uncaught">,
+    //                      "enabled" : <optional bool: enables the break type if true>
+    //                    }
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(SETEXCEPTIONBREAK));
+
+    QJsonObject args;
+
+    if (type == All)
+        args.insert(QLatin1String(TYPE), QLatin1String(ALL));
+    else if (type == Uncaught)
+        args.insert(QLatin1String(TYPE), QLatin1String(UNCAUGHT));
+
+    if (enabled)
+        args.insert(QLatin1String(ENABLED), enabled);
+
+    jsonVal.insert(QLatin1String(ARGUMENTS), args);
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+void QV4DebugClient::version()
+{
+    //    { "seq"       : <number>,
+    //      "type"      : "request",
+    //      "command"   : "version",
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(VERSION));
+    d->sendMessage(V8REQUEST, jsonVal);
+}
+
+QV4DebugClient::Response QV4DebugClient::response() const
+{
+    Q_D(const QV4DebugClient);
+    const QJsonObject value = QJsonDocument::fromJson(d->response).object();
+    return {
+        value.value(QLatin1String(COMMAND)).toString(),
+        value.value(QLatin1String("body"))
+    };
+}
+
+void QV4DebugClient::disconnect()
+{
+    //    { "seq"     : <number>,
+    //      "type"    : "request",
+    //      "command" : "disconnect",
+    //    }
+    VARIANTMAPINIT;
+    jsonVal.insert(QLatin1String(COMMAND), QLatin1String(DISCONNECT));
+    d->sendMessage(DISCONNECT, jsonVal);
+}
+
+void QV4DebugClientPrivate::onStateChanged(QQmlDebugClient::State state)
+{
+    if (state == QQmlDebugClient::Enabled)
+        flushSendBuffer();
+}
+
+void QV4DebugClient::messageReceived(const QByteArray &data)
+{
+    Q_D(QV4DebugClient);
+    QPacket ds(connection()->currentDataStreamVersion(), data);
+    QByteArray command;
+    ds >> command;
+
+    if (command == "V8DEBUG") {
+        QByteArray type;
+        ds >> type >> d->response;
+
+        if (type == CONNECT) {
+            emit connected();
+
+        } else if (type == INTERRUPT) {
+            emit interrupted();
+
+        } else if (type == V8MESSAGE) {
+            const QJsonObject value = QJsonDocument::fromJson(d->response).object();
+            QString type = value.value(QLatin1String(TYPE)).toString();
+
+            if (type == QLatin1String("response")) {
+
+                if (!value.value(QLatin1String("success")).toBool()) {
+                    emit failure();
+                    qDebug() << "Received success == false response from application:"
+                             << value.value(QLatin1String("message")).toString();
+                    return;
+                }
+
+                QString debugCommand(value.value(QLatin1String(COMMAND)).toString());
+                if (debugCommand == QLatin1String(BACKTRACE) ||
+                        debugCommand == QLatin1String(LOOKUP) ||
+                        debugCommand == QLatin1String(SETBREAKPOINT) ||
+                        debugCommand == QLatin1String(EVALUATE) ||
+                        debugCommand == QLatin1String(VERSION) ||
+                        debugCommand == QLatin1String(DISCONNECT) ||
+                        debugCommand == QLatin1String(GARBAGECOLLECTOR) ||
+                        debugCommand == QLatin1String(CHANGEBREAKPOINT) ||
+                        debugCommand == QLatin1String(CLEARBREAKPOINT) ||
+                        debugCommand == QLatin1String(FRAME) ||
+                        debugCommand == QLatin1String(SCOPE) ||
+                        debugCommand == QLatin1String(SCOPES) ||
+                        debugCommand == QLatin1String(SCRIPTS) ||
+                        debugCommand == QLatin1String(SOURCE) ||
+                        debugCommand == QLatin1String(SETEXCEPTIONBREAK)) {
+                    emit result();
+                } else {
+                    // DO NOTHING
+                }
+
+            } else if (type == QLatin1String(EVENT)) {
+                QString event(value.value(QLatin1String(EVENT)).toString());
+
+                if (event == QLatin1String("break") || event == QLatin1String("exception"))
+                    emit stopped();
+            }
+        }
+    }
+}
+
+void QV4DebugClientPrivate::sendMessage(const QByteArray &command, const QJsonObject &args)
+{
+    Q_Q(QV4DebugClient);
+    const QByteArray msg = packMessage(command, args);
+    if (q->state() == QQmlDebugClient::Enabled) {
+        q->sendMessage(msg);
+    } else {
+        sendBuffer.append(msg);
+    }
+}
+
+void QV4DebugClientPrivate::flushSendBuffer()
+{
+    foreach (const QByteArray &msg, sendBuffer)
+        sendMessage(msg);
+    sendBuffer.clear();
+}
+
+QByteArray QV4DebugClientPrivate::packMessage(const QByteArray &type, const QJsonObject &object)
+{
+    QPacket rs(connection->currentDataStreamVersion());
+    QByteArray cmd = "V8DEBUG";
+    rs << cmd << type << QJsonDocument(object).toJson(QJsonDocument::Compact);
+    return rs.data();
+}
+
+QT_END_NAMESPACE
diff --git a/src/qmldebug/qv4debugclient_p.h b/src/qmldebug/qv4debugclient_p.h
new file mode 100644
index 0000000000..fdcf4284c5
--- /dev/null
+++ b/src/qmldebug/qv4debugclient_p.h
@@ -0,0 +1,121 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QV4DEBUGCLIENT_P_H
+#define QV4DEBUGCLIENT_P_H
+
+#include <QtQmlDebug/private/qqmldebugclient_p.h>
+#include <QtCore/qjsonvalue.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+class QV4DebugClientPrivate;
+class QV4DebugClient : public QQmlDebugClient
+{
+    Q_OBJECT
+    Q_DECLARE_PRIVATE(QV4DebugClient)
+
+public:
+    enum StepAction
+    {
+        Continue,
+        In,
+        Out,
+        Next
+    };
+
+    enum Exception
+    {
+        All,
+        Uncaught
+    };
+
+    struct Response
+    {
+        QString command;
+        QJsonValue body;
+    };
+
+    QV4DebugClient(QQmlDebugConnection *connection);
+
+    void connect();
+    void disconnect();
+
+    void interrupt();
+    void continueDebugging(StepAction stepAction);
+    void evaluate(const QString &expr, int frame = -1, int context = -1);
+    void lookup(const QList<int> &handles, bool includeSource = false);
+    void backtrace(int fromFrame = -1, int toFrame = -1, bool bottom = false);
+    void frame(int number = -1);
+    void scope(int number = -1, int frameNumber = -1);
+    void scripts(int types = 4, const QList<int> &ids = QList<int>(), bool includeSource = false);
+    void setBreakpoint(const QString &target, int line = -1, int column = -1, bool enabled = true,
+                       const QString &condition = QString(), int ignoreCount = -1);
+    void clearBreakpoint(int breakpoint);
+    void changeBreakpoint(int breakpoint, bool enabled);
+    void setExceptionBreak(Exception type, bool enabled = false);
+    void version();
+
+    Response response() const;
+
+protected:
+    void messageReceived(const QByteArray &data) override;
+
+signals:
+    void connected();
+    void interrupted();
+    void result();
+    void failure();
+    void stopped();
+};
+
+QT_END_NAMESPACE
+
+#endif // QV4DEBUGCLIENT_P_H
diff --git a/src/qmldebug/qv4debugclient_p_p.h b/src/qmldebug/qv4debugclient_p_p.h
new file mode 100644
index 0000000000..993c281632
--- /dev/null
+++ b/src/qmldebug/qv4debugclient_p_p.h
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QV4DEBUGCLIENT_P_P_H
+#define QV4DEBUGCLIENT_P_P_H
+
+#include "qv4debugclient_p.h"
+#include "qqmldebugclient_p_p.h"
+
+#include <QtCore/qjsonobject.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+class QV4DebugClientPrivate : public QQmlDebugClientPrivate
+{
+    Q_DECLARE_PUBLIC(QV4DebugClient)
+
+public:
+    QV4DebugClientPrivate(QQmlDebugConnection *connection);
+
+    void sendMessage(const QByteArray &command, const QJsonObject &args = QJsonObject());
+    void flushSendBuffer();
+    QByteArray packMessage(const QByteArray &type, const QJsonObject &object);
+    void onStateChanged(QQmlDebugClient::State state);
+
+    int seq = 0;
+    QList<QByteArray> sendBuffer;
+    QByteArray response;
+};
+
+QT_END_NAMESPACE
+
+#endif // QV4DEBUGCLIENT_P_P_H