Provide a logical view of VM-internal maps in Observatory.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 2896d725180f662d382c2b980421d174e8c3de20..855ae0f57c0f89014f38f3c05355ebb71607bdc5 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -19377,11 +19377,12 @@ void Array::PrintJSONImpl(JSONStream* stream, bool ref) const {
   }
   {
     JSONArray jsarr(&jsobj, "elements");
+    Object& element = Object::Handle();

[koda, 2015/06/02 16:42:37]

Thanks for fixing this.

     for (intptr_t index = 0; index < Length(); index++) {
       JSONObject jselement(&jsarr);
       jselement.AddProperty("index", index);
 
-      Object& element = Object::Handle(At(index));
+      element = At(index);
       jselement.AddProperty("value", element);
     }
   }
@@ -19623,11 +19624,12 @@ void GrowableObjectArray::PrintJSONImpl(JSONStream* stream,
   }
   {
     JSONArray jsarr(&jsobj, "elements");
+    Object& element = Object::Handle();
     for (intptr_t index = 0; index < Length(); index++) {
       JSONObject jselement(&jsarr);
       jselement.AddProperty("index", index);
 
-      Object& element = Object::Handle(At(index));
+      element = At(index);
       jselement.AddProperty("value", element);
     }
   }
@@ -19720,8 +19722,11 @@ RawLinkedHashMap* LinkedHashMap::NewUninitialized(Heap::Space space) {
 
 
 const char* LinkedHashMap::ToCString() const {
-  // TODO(koda): Print key/value pairs.
-  return "_LinkedHashMap";
+  const char* format = "_LinkedHashMap len:%" Pd;
+  intptr_t len = OS::SNPrint(NULL, 0, format, Length()) + 1;

[koda, 2015/06/02 16:42:36]

Use Thread::Current()->zone()->PrintToString(...)

[rmacnak, 2015/06/02 17:33:31]

Much nicer. Updated Array::ToCString as well.

+  char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
+  OS::SNPrint(chars, len, format, Length());
+  return chars;
 }
 
 
@@ -19730,11 +19735,22 @@ void LinkedHashMap::PrintJSONImpl(JSONStream* stream, bool ref) const {
   PrintSharedInstanceJSON(&jsobj, ref);
   jsobj.AddProperty("kind", "Map");
   jsobj.AddServiceId(*this);
-  // TODO(koda): Print length.
+  jsobj.AddProperty("length", Length());
   if (ref) {
     return;
   }
-  // TODO(koda): Print key/value pairs.
+  {
+    JSONArray jsarr(&jsobj, "associations");
+    Object& object = Object::Handle();
+    LinkedHashMap::Iterator iterator(*this);
+    while (iterator.MoveNext()) {
+      JSONObject jsassoc(&jsarr);
+      object = iterator.CurrentKey();
+      jsassoc.AddProperty("key", object);
+      object = iterator.CurrentValue();
+      jsassoc.AddProperty("value", object);
+    }
+  }
 }