Bug 1038399. Add a ToJSON method to Web IDL dictionaries. r=bholley

dom/bindings/BindingDeclarations.h

@@ -35,6 +35,15 @@ struct DictionaryBase
 protected:
   bool ParseJSON(JSContext* aCx, const nsAString& aJSON,
                  JS::MutableHandle<JS::Value> aVal);
+
+  bool StringifyToJSON(JSContext* aCx,
+                       JS::MutableHandle<JS::Value> aValue,
+                       nsAString& aJSON);
+private:
+  // aString is expected to actually be an nsAString*.  Should only be
+  // called from StringifyToJSON.
+  static bool AppendJSONToString(const jschar* aJSONData, uint32_t aDataLength,
+                                 void* aString);
 };
 
 // Struct that serves as a base class for all typed arrays and array buffers and

dom/bindings/BindingUtils.cpp

@@ -1608,6 +1608,29 @@ DictionaryBase::ParseJSON(JSContext* aCx,
                       aJSON.Length(), aVal);
 }
 
+bool
+DictionaryBase::StringifyToJSON(JSContext* aCx,
+                                JS::MutableHandle<JS::Value> aValue,
+                                nsAString& aJSON)
+{
+  return JS_Stringify(aCx, aValue, JS::NullPtr(), JS::NullHandleValue,
+                      AppendJSONToString, &aJSON);
+}
+
+/* static */
+bool
+DictionaryBase::AppendJSONToString(const jschar* aJSONData,
+                                   uint32_t aDataLength,
+                                   void* aString)
+{
+  nsAString* string = static_cast<nsAString*>(aString);
+  string->Append(static_cast<const char16_t*>(aJSONData),
+                 aDataLength);
+  return true;
+}
+
+
+
 static JSString*
 ConcatJSString(JSContext* cx, const char* pre, JS::Handle<JSString*> str, const char* post)
 {

dom/bindings/Codegen.py

@@ -10828,6 +10828,20 @@ class CGDictionary(CGThing):
                 return Init(cx, json);
                 """))
 
+    def toJSONMethod(self):
+        return ClassMethod(
+            "ToJSON", "bool",
+            [Argument('nsAString&', 'aJSON')],
+            body=dedent("""
+                MOZ_ASSERT(NS_IsMainThread());
+                AutoJSAPI jsapi;
+                jsapi.Init();
+                JSContext *cx = jsapi.cx();
+                JSAutoCompartment ac(cx, xpc::GetSafeJSContextGlobal()); // Usage approved by bholley
+                JS::Rooted<JS::Value> obj(cx);
+                return ToObjectInternal(cx, &obj) && StringifyToJSON(cx, &obj, aJSON);
+            """))
+
     def toObjectInternalMethod(self):
         body = ""
         if self.needToInitIds:
@@ -10955,10 +10969,12 @@ class CGDictionary(CGThing):
         methods.append(self.initFromJSONMethod())
         try:
             methods.append(self.toObjectInternalMethod())
+            methods.append(self.toJSONMethod())
         except MethodNotNewObjectError:
             # If we can't have a ToObjectInternal() because one of our members
             # can only be returned from [NewObject] methods, then just skip
-            # generating ToObjectInternal().
+            # generating ToObjectInternal() and ToJSON (since the latter depens
+            # on the former).
             pass
         methods.append(self.traceDictionaryMethod())
 
@@ -11546,6 +11562,8 @@ class CGBindingRoot(CGThing):
 
         bindingHeaders["WrapperFactory.h"] = descriptors
         bindingHeaders["mozilla/dom/DOMJSClass.h"] = descriptors
+        bindingHeaders["mozilla/dom/ScriptSettings.h"] = dictionaries # AutoJSAPI
+        bindingHeaders["xpcpublic.h"] = dictionaries ## xpc::GetSafeJSContextGlobal
 
         # Do codegen for all the dictionaries.  We have to be a bit careful
         # here, because we have to generate these in order from least derived

dom/crypto/WebCryptoTask.cpp

@@ -2241,15 +2241,6 @@ private:
   }
 };
 
-static bool
-JSONCreator(const jschar* aBuf, uint32_t aLen, void* aData)
-{
-  nsAString* result = static_cast<nsAString*>(aData);
-  result->Append(static_cast<const char16_t*>(aBuf),
-                 static_cast<uint32_t>(aLen));
-  return true;
-}
-
 template<class KeyEncryptTask>
 class WrapKeyTask : public ExportKeyTask
 {
@@ -2273,30 +2264,11 @@ private:
   nsRefPtr<KeyEncryptTask> mTask;
   bool mResolved;
 
-  static bool StringifyJWK(const JsonWebKey& aJwk, nsAString& aRetVal)
-  {
-    // XXX: This should move into DictionaryBase and Codegen.py,
-    //      in the same way as ParseJSON is split out. (Bug 1038399)
-    // We use AutoSafeJSContext even though the exact compartment
-    // doesn't matter (since we're making an XPCOM string)
-    MOZ_ASSERT(NS_IsMainThread());
-    AutoSafeJSContext cx;
-    JS::Rooted<JS::Value> obj(cx);
-    bool ok = ToJSValue(cx, aJwk, &obj);
-    if (!ok) {
-      JS_ClearPendingException(cx);
-      return false;
-    }
-
-    return JS_Stringify(cx, &obj, JS::NullPtr(), JS::NullHandleValue,
-                        JSONCreator, &aRetVal);
-  }
-
   virtual nsresult AfterCrypto() MOZ_OVERRIDE {
     // If wrapping JWK, stringify the JSON
     if (mFormat.EqualsLiteral(WEBCRYPTO_KEY_FORMAT_JWK)) {
       nsAutoString json;
-      if (!StringifyJWK(mJwk, json)) {
+      if (!mJwk.ToJSON(json)) {
         return NS_ERROR_DOM_OPERATION_ERR;
       }