Mitigate private header problems in QtCreator by adding semi-private API

Add a semi-private API to get QScriptEngine for a QDeclarativeEngine. So far the qmljsdebugger lib in QtCreator
accessed the script engine via QDeclarativeEnginePrivate. Replace this by a minimal API that is still in a
private header, where we nevertheless can make some BC checks/guarantees.

Aaron Kennedy agreed with the idea.

Task-number: QTCREATORBUG-2179

7 files changed, 140 insertions, 3 deletions

diff --git a/src/declarative/debugger/debugger.pri b/src/declarative/debugger/debugger.pri
index 33d0843..25f7687 100644
--- a/src/declarative/debugger/debugger.pri
+++ b/src/declarative/debugger/debugger.pri
@@ -6,7 +6,8 @@ SOURCES += \
     $$PWD/qdeclarativedebugservice.cpp \
     $$PWD/qdeclarativedebugclient.cpp \
     $$PWD/qdeclarativedebug.cpp \
-    $$PWD/qdeclarativedebugtrace.cpp
+    $$PWD/qdeclarativedebugtrace.cpp \
+    $$PWD/qdeclarativedebughelper.cpp
 
 HEADERS += \
     $$PWD/qdeclarativedebuggerstatus_p.h \
@@ -14,4 +15,5 @@ HEADERS += \
     $$PWD/qdeclarativedebugservice_p.h \
     $$PWD/qdeclarativedebugclient_p.h \
     $$PWD/qdeclarativedebug_p.h \
-    $$PWD/qdeclarativedebugtrace_p.h
+    $$PWD/qdeclarativedebugtrace_p.h \
+    $$PWD/qdeclarativedebughelper_p.h
diff --git a/src/declarative/debugger/qdeclarativedebug_p.h b/src/declarative/debugger/qdeclarativedebug_p.h
index f0fc488..2b1a115 100644
--- a/src/declarative/debugger/qdeclarativedebug_p.h
+++ b/src/declarative/debugger/qdeclarativedebug_p.h
@@ -365,7 +365,6 @@ private:
     int m_queryId;
     QVariant m_expr;
     QVariant m_result;
-
 };
 
 QT_END_NAMESPACE
diff --git a/src/declarative/debugger/qdeclarativedebughelper.cpp b/src/declarative/debugger/qdeclarativedebughelper.cpp
new file mode 100644
index 0000000..99feff4
--- /dev/null
+++ b/src/declarative/debugger/qdeclarativedebughelper.cpp
@@ -0,0 +1,13 @@
+#include "private/qdeclarativedebughelper_p.h"
+#include "private/qdeclarativeengine_p.h"
+
+#include <QtScript/QScriptEngine>
+
+QT_BEGIN_NAMESPACE
+
+QScriptEngine *QDeclarativeDebugHelper::getScriptEngine(QDeclarativeEngine *engine)
+{
+    return QDeclarativeEnginePrivate::getScriptEngine(engine);
+}
+
+QT_END_NAMESPACE
diff --git a/src/declarative/debugger/qdeclarativedebughelper_p.h b/src/declarative/debugger/qdeclarativedebughelper_p.h
new file mode 100644
index 0000000..a403c45
--- /dev/null
+++ b/src/declarative/debugger/qdeclarativedebughelper_p.h
@@ -0,0 +1,25 @@
+#ifndef QDECLARATIVEDEBUGHELPER_P_H
+#define QDECLARATIVEDEBUGHELPER_P_H
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+class QScriptEngine;
+class QDeclarativeEngine;
+
+// Helper methods to access private API through a stable interface
+// This is used in the qmljsdebugger library of QtCreator.
+class Q_DECLARATIVE_EXPORT QDeclarativeDebugHelper
+{
+public:
+    static QScriptEngine *getScriptEngine(QDeclarativeEngine *engine);
+};
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QDECLARATIVEDEBUGHELPER_P_H
diff --git a/tests/auto/declarative/qdeclarativedebughelper/private_headers/qdeclarativedebughelper_p.h b/tests/auto/declarative/qdeclarativedebughelper/private_headers/qdeclarativedebughelper_p.h
new file mode 100644
index 0000000..a403c45
--- /dev/null
+++ b/tests/auto/declarative/qdeclarativedebughelper/private_headers/qdeclarativedebughelper_p.h
@@ -0,0 +1,25 @@
+#ifndef QDECLARATIVEDEBUGHELPER_P_H
+#define QDECLARATIVEDEBUGHELPER_P_H
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+class QScriptEngine;
+class QDeclarativeEngine;
+
+// Helper methods to access private API through a stable interface
+// This is used in the qmljsdebugger library of QtCreator.
+class Q_DECLARATIVE_EXPORT QDeclarativeDebugHelper
+{
+public:
+    static QScriptEngine *getScriptEngine(QDeclarativeEngine *engine);
+};
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QDECLARATIVEDEBUGHELPER_P_H
diff --git a/tests/auto/declarative/qdeclarativedebughelper/qdeclarativedebughelper.pro b/tests/auto/declarative/qdeclarativedebughelper/qdeclarativedebughelper.pro
new file mode 100644
index 0000000..c52c652
--- /dev/null
+++ b/tests/auto/declarative/qdeclarativedebughelper/qdeclarativedebughelper.pro
@@ -0,0 +1,5 @@
+load(qttest_p4)
+contains(QT_CONFIG,declarative): QT += network declarative script
+macx:CONFIG -= app_bundle
+
+SOURCES += tst_qdeclarativedebughelper.cpp
diff --git a/tests/auto/declarative/qdeclarativedebughelper/tst_qdeclarativedebughelper.cpp b/tests/auto/declarative/qdeclarativedebughelper/tst_qdeclarativedebughelper.cpp
new file mode 100644
index 0000000..db62455
--- /dev/null
+++ b/tests/auto/declarative/qdeclarativedebughelper/tst_qdeclarativedebughelper.cpp
@@ -0,0 +1,68 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** 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, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include <qtest.h>
+
+#include <QDeclarativeEngine>
+#include <private/qdeclarativeengine_p.h>
+
+// We have copied the header which is used in the qmljsdebugger (part of QtCreator)
+// to catch BC changes. Don't update it unless you know what you are doing!
+#include "private_headers/qdeclarativedebughelper_p.h"
+
+class tst_qdeclarativedebughelper : public QObject {
+    Q_OBJECT
+private slots:
+    void getScriptEngine();
+};
+
+void tst_qdeclarativedebughelper::getScriptEngine()
+{
+    QDeclarativeEngine engine;
+
+    QScriptEngine *scriptEngine = QDeclarativeDebugHelper::getScriptEngine(&engine);
+    QVERIFY(scriptEngine);
+    QCOMPARE(scriptEngine, QDeclarativeEnginePrivate::getScriptEngine(&engine));
+}
+
+QTEST_MAIN(tst_qdeclarativedebughelper)
+
+#include "tst_qdeclarativedebughelper.moc"
+