src: implement the new EmbedderGraph::AddEdge()

The signature of EmbedderGraph::AddEdge() has been changed so
the current implementation of JSGraph no longer compiles.
This patch updates the implementation accordingly.

Author: joyeecheung

src/heap_utils.cc

@@ -76,8 +76,8 @@ class JSGraph : public EmbedderGraph {
     return n;
   }
 
-  void AddEdge(Node* from, Node* to) override {
-    edges_[from].insert(to);
+  void AddEdge(Node* from, Node* to, const char* name = nullptr) override {
+    edges_[from].insert(std::make_pair(name, to));
   }
 
   MaybeLocal<Array> CreateObject() const {
@@ -92,6 +92,7 @@ class JSGraph : public EmbedderGraph {
     Local<String> size_string = FIXED_ONE_BYTE_STRING(isolate_, "size");
     Local<String> value_string = FIXED_ONE_BYTE_STRING(isolate_, "value");
     Local<String> wraps_string = FIXED_ONE_BYTE_STRING(isolate_, "wraps");
+    Local<String> to_string = FIXED_ONE_BYTE_STRING(isolate_, "to");
 
     for (const std::unique_ptr<Node>& n : nodes_)
       info_objects[n.get()] = Object::New(isolate_);
@@ -141,10 +142,23 @@ class JSGraph : public EmbedderGraph {
       }
 
       size_t i = 0;
-      for (Node* target : edge_info.second) {
-        if (edges.As<Array>()->Set(context,
-                                   i++,
-                                   info_objects[target]).IsNothing()) {
+      size_t j = 0;
+      for (const auto& edge : edge_info.second) {
+        Local<Object> to_object = info_objects[edge.second];
+        Local<Object> edge_info = Object::New(isolate_);
+        Local<Value> edge_name_value;
+        const char* edge_name = edge.first;
+        if (edge_name != nullptr &&
+            !String::NewFromUtf8(
+                 isolate_, edge_name, v8::NewStringType::kNormal)
+                 .ToLocal(&edge_name_value)) {
+          return MaybeLocal<Array>();
+        } else {
+          edge_name_value = Number::New(isolate_, j++);
+        }
+        if (edge_info->Set(context, name_string, edge_name_value).IsNothing() ||
+            edge_info->Set(context, to_string, to_object).IsNothing() ||
+            edges.As<Array>()->Set(context, i++, edge_info).IsNothing()) {
           return MaybeLocal<Array>();
         }
       }
@@ -158,7 +172,7 @@ class JSGraph : public EmbedderGraph {
   std::unordered_set<std::unique_ptr<Node>> nodes_;
   std::unordered_set<JSGraphJSNode*, JSGraphJSNode::Hash, JSGraphJSNode::Equal>
       engine_nodes_;
-  std::unordered_map<Node*, std::unordered_set<Node*>> edges_;
+  std::unordered_map<Node*, std::set<std::pair<const char*, Node*>>> edges_;
 };
 
 void BuildEmbedderGraph(const FunctionCallbackInfo<Value>& args) {

test/common/heap.js

@@ -47,15 +47,19 @@ class State {
     else
       assert.strictEqual(graph.length, expected.length);
     for (const expectedNode of expected) {
-      if (expectedNode.edges) {
+      if (expectedNode.children) {
         for (const expectedChild of expectedNode.children) {
-          const check = typeof expectedChild === 'function' ?
-            expectedChild : (node) => {
-              return node.name === expectedChild.name ||
-                (node.value &&
-                 node.value.constructor &&
-                 node.value.constructor.name === expectedChild.name);
-            };
+          const check = (edge) => {
+            // TODO(joyeecheung): check the edge names
+            const node = edge.to;
+            if (typeof expectedChild === 'function') {
+              return expectedChild(node);
+            }
+            return node.name === expectedChild.name ||
+              (node.value &&
+                node.value.constructor &&
+                node.value.constructor.name === expectedChild.name);
+          };
 
           assert(graph.some((node) => node.edges.some(check)),
                  `expected to find child ${util.inspect(expectedChild)} ` +