From 0754f55287f4652382332bce42cd8c7d27846ef1 Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@qt.io>
Date: Thu, 2 Aug 2018 15:44:12 +0200
Subject: Introduce a new mechanism to iterate over object properties

The old advanceIterator schema was extremely ugly and in addition
not flexible enough to support the requirements for Proxy.ownKeys
and some of the methods in Object

Implemented a new scheme through a OwnPropertyKeys method in the
Object VTable that creates and returns an iterator object. Ported
QJSValueIterator and for-in to use the new mechanism.

There's still many places where we use the old ObjectIterator (that
relies on advanceIterator). Those will be ported in subsequent
commits.

Change-Id: I091a9bea9ff6b2b63630cc336814700757a718be
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
---
 src/qml/jsruntime/qv4objectiterator.cpp | 81 +++++++++++++++++++++++++++------
 1 file changed, 67 insertions(+), 14 deletions(-)

(limited to 'src/qml/jsruntime/qv4objectiterator.cpp')

diff --git a/src/qml/jsruntime/qv4objectiterator.cpp b/src/qml/jsruntime/qv4objectiterator.cpp
index 73c09a864a..d4e07e3d77 100644
--- a/src/qml/jsruntime/qv4objectiterator.cpp
+++ b/src/qml/jsruntime/qv4objectiterator.cpp
@@ -43,6 +43,7 @@
 #include "qv4argumentsobject_p.h"
 #include "qv4string_p.h"
 #include "qv4iterator_p.h"
+#include "qv4propertykey_p.h"
 
 using namespace QV4;
 
@@ -51,20 +52,6 @@ void ForInIteratorPrototype::init(ExecutionEngine *)
     defineDefaultProperty(QStringLiteral("next"), method_next, 0);
 }
 
-ReturnedValue ForInIteratorPrototype::method_next(const FunctionObject *b, const Value *thisObject, const Value *, int)
-{
-    const ForInIteratorObject *forIn = thisObject->as<ForInIteratorObject>();
-    Q_ASSERT(forIn);
-    Scope scope(b->engine());
-    ScopedValue n(scope, forIn->nextPropertyName());
-    bool done = false;
-    if (n->asReturnedValue() == Encode::null()) {
-        done = true;
-        n = Primitive::undefinedValue();
-    }
-    return IteratorPrototype::createIterResultObject(scope.engine, n, done);
-}
-
 void ObjectIterator::init(const Object *o)
 {
     object->setM(o ? o->m() : nullptr);
@@ -200,7 +187,73 @@ DEFINE_OBJECT_VTABLE(ForInIteratorObject);
 void Heap::ForInIteratorObject::markObjects(Heap::Base *that, MarkStack *markStack)
 {
     ForInIteratorObject *o = static_cast<ForInIteratorObject *>(that);
+    o->object->mark(markStack);
     o->workArea[0].mark(markStack);
     o->workArea[1].mark(markStack);
     Object::markObjects(that, markStack);
 }
+
+void Heap::ForInIteratorObject::destroy()
+{
+    delete iterator;
+}
+
+ReturnedValue ForInIteratorPrototype::method_next(const FunctionObject *b, const Value *thisObject, const Value *, int)
+{
+    const ForInIteratorObject *forIn = static_cast<const ForInIteratorObject *>(thisObject);
+    Q_ASSERT(forIn);
+    Scope scope(b);
+
+    ScopedPropertyKey key(scope, forIn->nextProperty());
+    bool done = false;
+    if (!key->isValid())
+        done = true;
+    ScopedStringOrSymbol s(scope, key->toStringOrSymbol(scope.engine));
+    return IteratorPrototype::createIterResultObject(scope.engine, s, done);
+}
+
+
+PropertyKey ForInIteratorObject::nextProperty() const
+{
+    if (!d()->current)
+        return PropertyKey::invalid();
+
+    Scope scope(this);
+    ScopedObject c(scope, d()->current);
+    ScopedObject o(scope);
+    ScopedPropertyKey key(scope);
+    PropertyAttributes attrs;
+
+    while (1) {
+        while (1) {
+            key = d()->iterator->next(c, nullptr, &attrs);
+            if (!key->isValid())
+                break;
+            if (!attrs.isEnumerable() || key->isSymbol())
+                continue;
+            // check the property is not already defined earlier in the proto chain
+            if (d()->current != d()->object) {
+                o = d()->object;
+                bool shadowed = false;
+                while (o->d() != c->heapObject()) {
+                    if (o->getOwnProperty(key) != Attr_Invalid) {
+                        shadowed = true;
+                        break;
+                    }
+                    o = o->getPrototypeOf();
+                }
+                if (shadowed)
+                    continue;
+            }
+            return key;
+        }
+
+        c = c->getPrototypeOf();
+        d()->current.set(scope.engine, c->d());
+        if (!c)
+            break;
+        delete d()->iterator;
+        d()->iterator = c->ownPropertyKeys();
+    }
+    return PropertyKey::invalid();
+}
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