QmlJS: Share Context.

Previously Context was not entirely thread safe and had to be
copied locally. Now it is thread safe and its lifetime
managed by QSharedPointer.

The non-safe parts were moved into ScopeChain in a previous commit.

Change-Id: I851a93de85cbd6391dbea0fe33b011e2e093addb
Reviewed-on: http://codereview.qt.nokia.com/1695
Reviewed-by: Fawzi Mohamed <[email protected]>

17 files changed, 99 insertions, 58 deletions

diff --git a/src/libs/qmljs/qmljsbind.cpp b/src/libs/qmljs/qmljsbind.cpp
index 149812bbbe8..4349f3b99be 100644
--- a/src/libs/qmljs/qmljsbind.cpp
+++ b/src/libs/qmljs/qmljsbind.cpp
@@ -97,7 +97,7 @@ Interpreter::ObjectValue *Bind::findQmlObject(AST::Node *node) const
 }
 
 bool Bind::usesQmlPrototype(ObjectValue *prototype,
-                            const Context *context) const
+                            const ContextPtr &context) const
 {
     if (!prototype)
         return false;
diff --git a/src/libs/qmljs/qmljsbind.h b/src/libs/qmljs/qmljsbind.h
index 09c2f002ad0..6e7f7e65d87 100644
--- a/src/libs/qmljs/qmljsbind.h
+++ b/src/libs/qmljs/qmljsbind.h
@@ -62,7 +62,7 @@ public:
 
     Interpreter::ObjectValue *findQmlObject(AST::Node *node) const;
     bool usesQmlPrototype(Interpreter::ObjectValue *prototype,
-                          const Interpreter::Context *context) const;
+                          const Interpreter::ContextPtr &context) const;
 
     Interpreter::ObjectValue *findAttachedJSScope(AST::Node *node) const;
     bool isGroupedPropertyBinding(AST::Node *node) const;
diff --git a/src/libs/qmljs/qmljscheck.cpp b/src/libs/qmljs/qmljscheck.cpp
index 8924bbaabb2..dbc75cad049 100644
--- a/src/libs/qmljs/qmljscheck.cpp
+++ b/src/libs/qmljs/qmljscheck.cpp
@@ -365,10 +365,10 @@ private:
 } // end of anonymous namespace
 
 
-Check::Check(Document::Ptr doc, const Context *context)
+Check::Check(Document::Ptr doc, const ContextPtr &context)
     : _doc(doc)
-    , _context(*context)
-    , _scopeChain(doc, &_context)
+    , _context(context)
+    , _scopeChain(doc, _context)
     , _scopeBuilder(&_scopeChain)
     , _options(WarnDangerousNonStrictEqualityChecks | WarnBlocks | WarnWith
           | WarnVoid | WarnCommaExpression | WarnExpressionStatement
@@ -471,14 +471,14 @@ void Check::visitQmlObject(Node *ast, UiQualifiedId *typeId,
 
     bool typeError = false;
     const SourceLocation typeErrorLocation = fullLocationForQualifiedId(typeId);
-    const ObjectValue *prototype = _context.lookupType(_doc.data(), typeId);
+    const ObjectValue *prototype = _context->lookupType(_doc.data(), typeId);
     if (!prototype) {
         typeError = true;
         if (_options & ErrCheckTypeErrors)
             error(typeErrorLocation,
                   Check::tr("unknown type"));
     } else {
-        PrototypeIterator iter(prototype, &_context);
+        PrototypeIterator iter(prototype, _context);
         QList<const ObjectValue *> prototypes = iter.all();
         if (iter.error() != PrototypeIterator::NoError)
             typeError = true;
@@ -610,7 +610,7 @@ bool Check::visit(IdentifierExpression *ast)
         if (!_lastValue)
             error(ast->identifierToken, tr("unknown identifier"));
         if (const Reference *ref = value_cast<const Reference *>(_lastValue)) {
-            _lastValue = _context.lookupReference(ref);
+            _lastValue = _context->lookupReference(ref);
             if (!_lastValue)
                 error(ast->identifierToken, tr("could not resolve"));
         }
@@ -635,7 +635,7 @@ bool Check::visit(FieldMemberExpression *ast)
         _lastValue = 0;
         return false;
     }
-    _lastValue = obj->lookupMember(ast->name->asString(), &_context);
+    _lastValue = obj->lookupMember(ast->name->asString(), _context);
     if (!_lastValue)
         error(ast->identifierToken, tr("unknown member"));
     return false;
@@ -878,7 +878,7 @@ const Value *Check::checkScopeObjectMember(const UiQualifiedId *id)
     // global lookup for first part of id
     const Value *value = 0;
     for (int i = scopeObjects.size() - 1; i >= 0; --i) {
-        value = scopeObjects[i]->lookupMember(propertyName, &_context);
+        value = scopeObjects[i]->lookupMember(propertyName, _context);
         if (value)
             break;
     }
@@ -894,7 +894,7 @@ const Value *Check::checkScopeObjectMember(const UiQualifiedId *id)
 
     // resolve references
     if (const Reference *ref = value->asReference())
-        value = _context.lookupReference(ref);
+        value = _context->lookupReference(ref);
 
     // member lookup
     const UiQualifiedId *idPart = id;
@@ -915,7 +915,7 @@ const Value *Check::checkScopeObjectMember(const UiQualifiedId *id)
         idPart = idPart->next;
         propertyName = idPart->name->asString();
 
-        value = objectValue->lookupMember(propertyName, &_context);
+        value = objectValue->lookupMember(propertyName, _context);
         if (! value) {
             error(idPart->identifierToken,
                   Check::tr("'%1' is not a member of '%2'").arg(
diff --git a/src/libs/qmljs/qmljscheck.h b/src/libs/qmljs/qmljscheck.h
index 84a0977c566..72c84fc7d36 100644
--- a/src/libs/qmljs/qmljscheck.h
+++ b/src/libs/qmljs/qmljscheck.h
@@ -54,7 +54,7 @@ class QMLJS_EXPORT Check: protected AST::Visitor
 
 public:
     // prefer taking root scope chain?
-    Check(Document::Ptr doc, const Interpreter::Context *context);
+    Check(Document::Ptr doc, const Interpreter::ContextPtr &context);
     virtual ~Check();
 
     QList<DiagnosticMessage> operator()();
@@ -128,7 +128,7 @@ private:
 
     Document::Ptr _doc;
 
-    Interpreter::Context _context;
+    Interpreter::ContextPtr _context;
     Interpreter::ScopeChain _scopeChain;
     ScopeBuilder _scopeBuilder;
 
diff --git a/src/libs/qmljs/qmljscontext.cpp b/src/libs/qmljs/qmljscontext.cpp
index 2d659c0ccbd..7e9fc62de02 100644
--- a/src/libs/qmljs/qmljscontext.cpp
+++ b/src/libs/qmljs/qmljscontext.cpp
@@ -38,6 +38,13 @@ using namespace QmlJS;
 using namespace QmlJS::AST;
 using namespace QmlJS::Interpreter;
 
+ContextPtr Context::create(const QmlJS::Snapshot &snapshot, ValueOwner *valueOwner, const ImportsPerDocument &imports)
+{
+    QSharedPointer<Context> result(new Context(snapshot, valueOwner, imports));
+    result->_ptr = result;
+    return result;
+}
+
 Context::Context(const QmlJS::Snapshot &snapshot, ValueOwner *valueOwner, const ImportsPerDocument &imports)
     : _snapshot(snapshot),
       _valueOwner(valueOwner),
@@ -49,6 +56,11 @@ Context::~Context()
 {
 }
 
+ContextPtr Context::ptr() const
+{
+    return _ptr.toStrongRef();
+}
+
 // the values is only guaranteed to live as long as the context
 ValueOwner *Context::valueOwner() const
 {
@@ -117,7 +129,7 @@ const ObjectValue *Context::lookupType(const QmlJS::Document *doc, const QString
 
 const Value *Context::lookupReference(const Value *value) const
 {
-    ReferenceContext refContext(this);
+    ReferenceContext refContext(ptr());
     return refContext.lookupReference(value);
 }
 
@@ -137,7 +149,7 @@ QString Context::defaultPropertyName(const ObjectValue *object) const
     return QString();
 }
 
-ReferenceContext::ReferenceContext(const Context *context)
+ReferenceContext::ReferenceContext(const ContextPtr &context)
     : m_context(context)
 {}
 
@@ -157,12 +169,12 @@ const Value *ReferenceContext::lookupReference(const Value *value)
     return v;
 }
 
-const Context *ReferenceContext::context() const
+const ContextPtr &ReferenceContext::context() const
 {
     return m_context;
 }
 
-ReferenceContext::operator const Context *() const
+ReferenceContext::operator const ContextPtr &() const
 {
     return m_context;
 }
diff --git a/src/libs/qmljs/qmljscontext.h b/src/libs/qmljs/qmljscontext.h
index 5d28c5872a9..c33674e27f8 100644
--- a/src/libs/qmljs/qmljscontext.h
+++ b/src/libs/qmljs/qmljscontext.h
@@ -45,18 +45,22 @@ class Snapshot;
 
 namespace Interpreter {
 
+class Context;
+typedef QSharedPointer<const Context> ContextPtr;
+
 // shared among threads, completely threadsafe
-// currently also safe to copy, but will be deprecated
 class QMLJS_EXPORT Context
 {
+    Q_DISABLE_COPY(Context)
 public:
-    typedef QSharedPointer<Context> Ptr;
     typedef QHash<const Document *, QSharedPointer<const Imports> > ImportsPerDocument;
 
     // Context takes ownership of valueOwner
-    Context(const Snapshot &snapshot, ValueOwner *valueOwner, const ImportsPerDocument &imports);
+    static ContextPtr create(const Snapshot &snapshot, ValueOwner *valueOwner, const ImportsPerDocument &imports);
     ~Context();
 
+    ContextPtr ptr() const;
+
     ValueOwner *valueOwner() const;
     Snapshot snapshot() const;
 
@@ -70,9 +74,13 @@ public:
     QString defaultPropertyName(const ObjectValue *object) const;
 
 private:
+    // Context takes ownership of valueOwner
+    Context(const Snapshot &snapshot, ValueOwner *valueOwner, const ImportsPerDocument &imports);
+
     Snapshot _snapshot;
     QSharedPointer<ValueOwner> _valueOwner;
     ImportsPerDocument _imports;
+    QWeakPointer<const Context> _ptr;
 };
 
 // for looking up references
@@ -80,15 +88,15 @@ class QMLJS_EXPORT ReferenceContext
 {
 public:
     // implicit conversion ok
-    ReferenceContext(const Context *context);
+    ReferenceContext(const ContextPtr &context);
 
     const Value *lookupReference(const Value *value);
 
-    const Context *context() const;
-    operator const Context *() const;
+    const ContextPtr &context() const;
+    operator const ContextPtr &() const;
 
 private:
-    const Context *m_context;
+    const ContextPtr &m_context;
     QList<const Reference *> m_references;
 };
 
diff --git a/src/libs/qmljs/qmljsevaluate.h b/src/libs/qmljs/qmljsevaluate.h
index d7316449bde..3d65e31d973 100644
--- a/src/libs/qmljs/qmljsevaluate.h
+++ b/src/libs/qmljs/qmljsevaluate.h
@@ -165,7 +165,7 @@ protected:
 private:
     QmlJS::Document::Ptr _doc;
     Interpreter::ValueOwner *_valueOwner;
-    const Interpreter::Context *_context;
+    Interpreter::ContextPtr _context;
     const Interpreter::ScopeChain *_scopeChain;
     const Interpreter::ObjectValue *_scope;
     const Interpreter::Value *_result;
diff --git a/src/libs/qmljs/qmljsinterpreter.cpp b/src/libs/qmljs/qmljsinterpreter.cpp
index d44c6065fd3..711bcc04656 100644
--- a/src/libs/qmljs/qmljsinterpreter.cpp
+++ b/src/libs/qmljs/qmljsinterpreter.cpp
@@ -888,7 +888,7 @@ const Value *ObjectValue::lookupMember(const QString &name, const Context *conte
         }
     }
 
-    if (examinePrototypes) {
+    if (examinePrototypes && context) {
         PrototypeIterator iter(this, context);
         iter.next(); // skip this
         while (iter.hasNext()) {
@@ -913,6 +913,16 @@ PrototypeIterator::PrototypeIterator(const ObjectValue *start, const Context *co
         m_prototypes.reserve(10);
 }
 
+PrototypeIterator::PrototypeIterator(const ObjectValue *start, const ContextPtr &context)
+    : m_current(0)
+    , m_next(start)
+    , m_context(context.data())
+    , m_error(NoError)
+{
+    if (start)
+        m_prototypes.reserve(10);
+}
+
 bool PrototypeIterator::hasNext()
 {
     if (m_next)
@@ -1422,14 +1432,14 @@ void ConvertToNumber::visit(const StringValue *)
 
 void ConvertToNumber::visit(const ObjectValue *object)
 {
-    if (const FunctionValue *valueOfMember = value_cast<const FunctionValue *>(object->lookupMember("valueOf", 0))) {
+    if (const FunctionValue *valueOfMember = value_cast<const FunctionValue *>(object->lookupMember("valueOf", ContextPtr()))) {
         _result = value_cast<const NumberValue *>(valueOfMember->call(object)); // ### invoke convert-to-number?
     }
 }
 
 void ConvertToNumber::visit(const FunctionValue *object)
 {
-    if (const FunctionValue *valueOfMember = value_cast<const FunctionValue *>(object->lookupMember("valueOf", 0))) {
+    if (const FunctionValue *valueOfMember = value_cast<const FunctionValue *>(object->lookupMember("valueOf", ContextPtr()))) {
         _result = value_cast<const NumberValue *>(valueOfMember->call(object)); // ### invoke convert-to-number?
     }
 }
@@ -1483,14 +1493,14 @@ void ConvertToString::visit(const StringValue *value)
 
 void ConvertToString::visit(const ObjectValue *object)
 {
-    if (const FunctionValue *toStringMember = value_cast<const FunctionValue *>(object->lookupMember("toString", 0))) {
+    if (const FunctionValue *toStringMember = value_cast<const FunctionValue *>(object->lookupMember("toString", ContextPtr()))) {
         _result = value_cast<const StringValue *>(toStringMember->call(object)); // ### invoke convert-to-string?
     }
 }
 
 void ConvertToString::visit(const FunctionValue *object)
 {
-    if (const FunctionValue *toStringMember = value_cast<const FunctionValue *>(object->lookupMember("toString", 0))) {
+    if (const FunctionValue *toStringMember = value_cast<const FunctionValue *>(object->lookupMember("toString", ContextPtr()))) {
         _result = value_cast<const StringValue *>(toStringMember->call(object)); // ### invoke convert-to-string?
     }
 }
diff --git a/src/libs/qmljs/qmljsinterpreter.h b/src/libs/qmljs/qmljsinterpreter.h
index c88e7aaa793..0bd1d357186 100644
--- a/src/libs/qmljs/qmljsinterpreter.h
+++ b/src/libs/qmljs/qmljsinterpreter.h
@@ -75,6 +75,7 @@ class Imports;
 class TypeScope;
 class JSImportScope;
 class Context;
+typedef QSharedPointer<const Context> ContextPtr;
 class ReferenceContext;
 
 typedef QList<const Value *> ValueList;
@@ -334,6 +335,8 @@ public:
     const Value *prototype() const;
     // prototypes may form a cycle: use PrototypeIterator!
     const ObjectValue *prototype(const Context *context) const;
+    const ObjectValue *prototype(const ContextPtr &context) const
+    { return prototype(context.data()); }
     void setPrototype(const Value *prototype);
 
     virtual void processMembers(MemberProcessor *processor) const;
@@ -344,6 +347,10 @@ public:
     virtual const Value *lookupMember(const QString &name, const Context *context,
                                       const ObjectValue **foundInObject = 0,
                                       bool examinePrototypes = true) const;
+    const Value *lookupMember(const QString &name, const ContextPtr &context,
+                              const ObjectValue **foundInObject = 0,
+                              bool examinePrototypes = true) const
+    { return lookupMember(name, context.data(), foundInObject, examinePrototypes); }
 
     // Value interface
     virtual const ObjectValue *asObjectValue() const;
@@ -372,6 +379,7 @@ public:
     };
 
     PrototypeIterator(const ObjectValue *start, const Context *context);
+    PrototypeIterator(const ObjectValue *start, const ContextPtr &context);
 
     bool hasNext();
     const ObjectValue *peekNext();
diff --git a/src/libs/qmljs/qmljslink.cpp b/src/libs/qmljs/qmljslink.cpp
index 9ac19e71513..9035d7e5148 100644
--- a/src/libs/qmljs/qmljslink.cpp
+++ b/src/libs/qmljs/qmljslink.cpp
@@ -130,19 +130,19 @@ Link::Link(const Snapshot &snapshot, const QStringList &importPaths, const Libra
     }
 }
 
-Context Link::operator()(QHash<QString, QList<DiagnosticMessage> > *messages)
+ContextPtr Link::operator()(QHash<QString, QList<DiagnosticMessage> > *messages)
 {
     Q_D(Link);
     d->allDiagnosticMessages = messages;
-    return Context(d->snapshot, d->valueOwner, linkImports());
+    return Context::create(d->snapshot, d->valueOwner, linkImports());
 }
 
-Context Link::operator()(const Document::Ptr &doc, QList<DiagnosticMessage> *messages)
+ContextPtr Link::operator()(const Document::Ptr &doc, QList<DiagnosticMessage> *messages)
 {
     Q_D(Link);
     d->doc = doc;
     d->diagnosticMessages = messages;
-    return Context(d->snapshot, d->valueOwner, linkImports());
+    return Context::create(d->snapshot, d->valueOwner, linkImports());
 }
 
 Link::~Link()
diff --git a/src/libs/qmljs/qmljslink.h b/src/libs/qmljs/qmljslink.h
index 16ca6698e79..0a941ed8447 100644
--- a/src/libs/qmljs/qmljslink.h
+++ b/src/libs/qmljs/qmljslink.h
@@ -58,11 +58,11 @@ public:
     Link(const Snapshot &snapshot, const QStringList &importPaths, const LibraryInfo &builtins);
 
     // Link all documents in snapshot, collecting all diagnostic messages (if messages != 0)
-    Interpreter::Context operator()(QHash<QString, QList<DiagnosticMessage> > *messages = 0);
+    Interpreter::ContextPtr operator()(QHash<QString, QList<DiagnosticMessage> > *messages = 0);
 
     // Link all documents in snapshot, appending the diagnostic messages
     // for 'doc' in 'messages'
-    Interpreter::Context operator()(const Document::Ptr &doc, QList<DiagnosticMessage> *messages);
+    Interpreter::ContextPtr operator()(const Document::Ptr &doc, QList<DiagnosticMessage> *messages);
 
     ~Link();
 
diff --git a/src/libs/qmljs/qmljslookupcontext.cpp b/src/libs/qmljs/qmljslookupcontext.cpp
index 389a23fb86c..0f8de513d2a 100644
--- a/src/libs/qmljs/qmljslookupcontext.cpp
+++ b/src/libs/qmljs/qmljslookupcontext.cpp
@@ -37,6 +37,7 @@
 #include "qmljsmodelmanagerinterface.h"
 #include "qmljsevaluate.h"
 #include "qmljsscopechain.h"
+#include "qmljscontext.h"
 
 using namespace QmlJS;
 
@@ -48,25 +49,25 @@ public:
         , context(Link(snapshot,
                        ModelManagerInterface::instance()->importPaths(),
                        ModelManagerInterface::instance()->builtins(doc))())
-        , scopeChain(doc, &context)
+        , scopeChain(doc, context)
     {
         ScopeBuilder scopeBuilder(&scopeChain);
         scopeBuilder.push(path);
     }
 
     LookupContextData(Document::Ptr doc,
-                      const Interpreter::Context &context,
+                      const Interpreter::ContextPtr &context,
                       const QList<AST::Node *> &path)
         : doc(doc)
         , context(context)
-        , scopeChain(doc, &context)
+        , scopeChain(doc, context)
     {
         ScopeBuilder scopeBuilder(&scopeChain);
         scopeBuilder.push(path);
     }
 
     Document::Ptr doc;
-    Interpreter::Context context;
+    Interpreter::ContextPtr context;
     Interpreter::ScopeChain scopeChain;
 };
 
@@ -76,7 +77,7 @@ LookupContext::LookupContext(Document::Ptr doc, const Snapshot &snapshot, const
 }
 
 LookupContext::LookupContext(const Document::Ptr doc,
-                             const Interpreter::Context &context,
+                             const Interpreter::ContextPtr &context,
                              const QList<AST::Node *> &path)
     : d(new LookupContextData(doc, context, path))
 {
@@ -93,7 +94,7 @@ LookupContext::Ptr LookupContext::create(Document::Ptr doc, const Snapshot &snap
 }
 
 LookupContext::Ptr LookupContext::create(const Document::Ptr doc,
-                                         const Interpreter::Context &context,
+                                         const Interpreter::ContextPtr &context,
                                          const QList<AST::Node *> &path)
 {
     Ptr ptr(new LookupContext(doc, context, path));
@@ -113,19 +114,19 @@ Document::Ptr LookupContext::document() const
 
 Snapshot LookupContext::snapshot() const
 {
-    return d->context.snapshot();
+    return d->context->snapshot();
 }
 
 // the engine is only guaranteed to live as long as the LookupContext
 Interpreter::ValueOwner *LookupContext::valueOwner() const
 {
-    return d->context.valueOwner();
+    return d->context->valueOwner();
 }
 
 // the context is only guaranteed to live as long as the LookupContext
-const Interpreter::Context *LookupContext::context() const
+const Interpreter::ContextPtr &LookupContext::context() const
 {
-    return &d->context;
+    return d->context;
 }
 
 const Interpreter::ScopeChain &LookupContext::scopeChain() const
diff --git a/src/libs/qmljs/qmljslookupcontext.h b/src/libs/qmljs/qmljslookupcontext.h
index f71ae802847..12f9f7d6a92 100644
--- a/src/libs/qmljs/qmljslookupcontext.h
+++ b/src/libs/qmljs/qmljslookupcontext.h
@@ -34,7 +34,6 @@
 #define QMLJSLOOKUPCONTEXT_H
 
 #include "qmljsdocument.h"
-#include "qmljscontext.h"
 #include "parser/qmljsastfwd_p.h"
 
 #include <QtCore/QSharedPointer>
@@ -47,6 +46,8 @@ class LookupContextData;
 namespace Interpreter {
 class Value;
 class Context;
+typedef QSharedPointer<const Context> ContextPtr;
+class ValueOwner;
 class ScopeChain;
 }
 
@@ -56,7 +57,7 @@ class QMLJS_EXPORT LookupContext
 
     LookupContext(const Document::Ptr doc, const Snapshot &snapshot, const QList<AST::Node *> &path);
     LookupContext(const Document::Ptr doc,
-                  const Interpreter::Context &context,
+                  const Interpreter::ContextPtr &context,
                   const QList<AST::Node *> &path);
 
 public:
@@ -68,7 +69,7 @@ public:
     static Ptr create(const Document::Ptr doc, const Snapshot &snapshot,
                       const QList<AST::Node *> &path);
     static Ptr create(const Document::Ptr doc,
-                      const Interpreter::Context &context,
+                      const Interpreter::ContextPtr &context,
                       const QList<AST::Node *> &path);
 
     const Interpreter::Value *evaluate(AST::Node *node) const;
@@ -76,7 +77,7 @@ public:
     Document::Ptr document() const;
     Snapshot snapshot() const;
     Interpreter::ValueOwner *valueOwner() const;
-    const Interpreter::Context *context() const;
+    const Interpreter::ContextPtr &context() const;
     const Interpreter::ScopeChain &scopeChain() const;
 
 private:
diff --git a/src/libs/qmljs/qmljsscopebuilder.cpp b/src/libs/qmljs/qmljsscopebuilder.cpp
index 90e97502df3..476ff2bde7d 100644
--- a/src/libs/qmljs/qmljsscopebuilder.cpp
+++ b/src/libs/qmljs/qmljsscopebuilder.cpp
@@ -224,7 +224,7 @@ const Value *ScopeBuilder::scopeObjectLookup(AST::UiQualifiedId *id)
 }
 
 
-const ObjectValue *ScopeBuilder::isPropertyChangesObject(const Context *context,
+const ObjectValue *ScopeBuilder::isPropertyChangesObject(const ContextPtr &context,
                                                    const ObjectValue *object)
 {
     PrototypeIterator iter(object, context);
diff --git a/src/libs/qmljs/qmljsscopebuilder.h b/src/libs/qmljs/qmljsscopebuilder.h
index 34982da9a8e..b33f3cec347 100644
--- a/src/libs/qmljs/qmljsscopebuilder.h
+++ b/src/libs/qmljs/qmljsscopebuilder.h
@@ -42,6 +42,7 @@ namespace QmlJS {
 namespace Interpreter {
 class QmlComponentChain;
 class Context;
+typedef QSharedPointer<const Context> ContextPtr;
 class ObjectValue;
 class Value;
 class ScopeChain;
@@ -61,7 +62,7 @@ public:
     void push(const QList<AST::Node *> &nodes);
     void pop();
 
-    static const Interpreter::ObjectValue *isPropertyChangesObject(const Interpreter::Context *context, const Interpreter::ObjectValue *object);
+    static const Interpreter::ObjectValue *isPropertyChangesObject(const Interpreter::ContextPtr &context, const Interpreter::ObjectValue *object);
 
 private:
     void setQmlScopeObject(AST::Node *node);
diff --git a/src/libs/qmljs/qmljsscopechain.cpp b/src/libs/qmljs/qmljsscopechain.cpp
index 2b5cda90f83..4e9e25d1987 100644
--- a/src/libs/qmljs/qmljsscopechain.cpp
+++ b/src/libs/qmljs/qmljsscopechain.cpp
@@ -62,7 +62,7 @@ void QmlComponentChain::addInstantiatingComponent(const QmlComponentChain *compo
 }
 
 
-ScopeChain::ScopeChain(const Document::Ptr &document, const Context *context)
+ScopeChain::ScopeChain(const Document::Ptr &document, const ContextPtr &context)
     : m_document(document)
     , m_context(context)
     , m_globalScope(0)
@@ -78,7 +78,7 @@ Document::Ptr ScopeChain::document() const
     return m_document;
 }
 
-const Context *ScopeChain::context() const
+const ContextPtr &ScopeChain::context() const
 {
     return m_context;
 }
diff --git a/src/libs/qmljs/qmljsscopechain.h b/src/libs/qmljs/qmljsscopechain.h
index b937cc6809a..5b2e8f7d639 100644
--- a/src/libs/qmljs/qmljsscopechain.h
+++ b/src/libs/qmljs/qmljsscopechain.h
@@ -73,10 +73,10 @@ private:
 class QMLJS_EXPORT ScopeChain
 {
 public:
-    explicit ScopeChain(const Document::Ptr &document, const Context *context);
+    explicit ScopeChain(const Document::Ptr &document, const ContextPtr &context);
 
     Document::Ptr document() const;
-    const Context *context() const;
+    const ContextPtr &context() const;
 
     const Value *lookup(const QString &name, const ObjectValue **foundInScope = 0) const;
 
@@ -108,7 +108,7 @@ private:
 
 
     Document::Ptr m_document;
-    const Context *m_context;
+    ContextPtr m_context;
 
     const ObjectValue *m_globalScope;
     QSharedPointer<const QmlComponentChain> m_qmlComponentScope;