V4 Debugger: Add an option to pass additional context for evaluate

Interpret the "context" option as an ID for a QObject whose QML context
is then injected when evaluating the expression. The QObject needs to
be tracked by some other debug service for this to work, e.g. the QML
debugger or the inspector.

Task-number: QTCREATORBUG-17177
Change-Id: I6a9e8b9ae23e8bb67ed1905a2ef73f7c4faeb990
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

3 files changed, 34 insertions, 18 deletions

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
index 4e4048f6ad..6c1e353b4d 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
@@ -42,6 +42,7 @@
 #include <private/qv4script_p.h>
 #include <private/qqmlcontext_p.h>
 #include <private/qv4qobjectwrapper_p.h>
+#include <private/qqmldebugservice_p.h>
 
 #include <QtQml/qqmlengine.h>
 
@@ -51,9 +52,10 @@ QV4DebugJob::~QV4DebugJob()
 {
 }
 
-JavaScriptJob::JavaScriptJob(QV4::ExecutionEngine *engine, int frameNr,
-                                   const QString &script) :
-    engine(engine), frameNr(frameNr), script(script), resultIsException(false)
+JavaScriptJob::JavaScriptJob(QV4::ExecutionEngine *engine, int frameNr, int context,
+                             const QString &script) :
+    engine(engine), frameNr(frameNr), context(context), script(script),
+    resultIsException(false)
 {}
 
 void JavaScriptJob::run()
@@ -64,7 +66,23 @@ void JavaScriptJob::run()
 
     QV4::ExecutionContext *ctx = engine->currentContext;
     QObject scopeObject;
-    if (frameNr < 0) { // Use QML context if available
+
+    if (frameNr > 0) {
+        for (int i = 0; i < frameNr; ++i) {
+            ctx = engine->parentContext(ctx);
+        }
+        engine->pushContext(ctx);
+        ctx = engine->currentContext;
+    }
+
+    if (context >= 0) {
+        QQmlContext *extraContext = qmlContext(QQmlDebugService::objectForId(context));
+        if (extraContext) {
+            engine->pushContext(ctx->newQmlContext(QQmlContextData::get(extraContext),
+                                                   &scopeObject));
+            ctx = engine->currentContext;
+        }
+    } else if (frameNr < 0) { // Use QML context if available
         QQmlEngine *qmlEngine = engine->qmlEngine();
         if (qmlEngine) {
             QQmlContext *qmlRootContext = qmlEngine->rootContext();
@@ -88,13 +106,6 @@ void JavaScriptJob::run()
             engine->pushContext(ctx->newWithContext(withContext->toObject(engine)));
             ctx = engine->currentContext;
         }
-    } else {
-        if (frameNr > 0) {
-            for (int i = 0; i < frameNr; ++i) {
-                ctx = engine->parentContext(ctx);
-            }
-            engine->pushContext(ctx);
-        }
     }
 
     QV4::Script script(ctx, this->script);
@@ -224,8 +235,9 @@ const QString &ValueLookupJob::exceptionMessage() const
 }
 
 ExpressionEvalJob::ExpressionEvalJob(QV4::ExecutionEngine *engine, int frameNr,
-                                     const QString &expression, QV4DataCollector *collector) :
-    JavaScriptJob(engine, frameNr, expression), collector(collector)
+                                     int context, const QString &expression,
+                                     QV4DataCollector *collector) :
+    JavaScriptJob(engine, frameNr, context, expression), collector(collector)
 {
 }
 
@@ -271,7 +283,7 @@ const QStringList &GatherSourcesJob::result() const
 }
 
 EvalJob::EvalJob(QV4::ExecutionEngine *engine, const QString &script) :
-    JavaScriptJob(engine, /*frameNr*/-1, script), result(false)
+    JavaScriptJob(engine, /*frameNr*/-1, /*context*/ -1, script), result(false)
 {}
 
 void EvalJob::handleResult(QV4::ScopedValue &result)
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.h b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.h
index b28adffae5..00d3e6206a 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.h
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.h
@@ -60,11 +60,12 @@ class JavaScriptJob : public QV4DebugJob
 {
     QV4::ExecutionEngine *engine;
     int frameNr;
+    int context;
     const QString &script;
     bool resultIsException;
 
 public:
-    JavaScriptJob(QV4::ExecutionEngine *engine, int frameNr, const QString &script);
+    JavaScriptJob(QV4::ExecutionEngine *engine, int frameNr, int context, const QString &script);
     void run() override;
     bool hasExeption() const;
 
@@ -135,8 +136,8 @@ class ExpressionEvalJob: public JavaScriptJob
     QJsonArray collectedRefs;
 
 public:
-    ExpressionEvalJob(QV4::ExecutionEngine *engine, int frameNr, const QString &expression,
-                      QV4DataCollector *collector);
+    ExpressionEvalJob(QV4::ExecutionEngine *engine, int frameNr, int context,
+                      const QString &expression, QV4DataCollector *collector);
     void handleResult(QV4::ScopedValue &value) override;
     const QString &exceptionMessage() const;
     const QJsonObject &returnValue() const;
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
index de97b5437b..1d2cc092dc 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
@@ -177,6 +177,7 @@ public:
         body.insert(QStringLiteral("V8Version"),
                     QLatin1String("this is not V8, this is V4 in Qt " QT_VERSION_STR));
         body.insert(QStringLiteral("UnpausedEvaluate"), true);
+        body.insert(QStringLiteral("ContextEvaluate"), true);
         addBody(body);
     }
 };
@@ -610,6 +611,7 @@ public:
     {
         QJsonObject arguments = req.value(QLatin1String("arguments")).toObject();
         QString expression = arguments.value(QLatin1String("expression")).toString();
+        int context = arguments.value(QLatin1String("context")).toInt(-1);
         int frame = -1;
 
         QV4Debugger *debugger = debugService->debuggerAgent.pausedDebugger();
@@ -627,7 +629,8 @@ public:
             frame = arguments.value(QLatin1String("frame")).toInt(0);
         }
 
-        ExpressionEvalJob job(debugger->engine(), frame, expression, debugger->collector());
+        ExpressionEvalJob job(debugger->engine(), frame, context, expression,
+                              debugger->collector());
         debugger->runInEngine(&job);
         if (job.hasExeption()) {
             createErrorResponse(job.exceptionMessage());