Bug 1524688: Part 1a - Support static registration JS components. r=mccr8

--HG--
extra : source : 68eb174a337b20e64583ae8afd45d479a3f54b61

build/docs/defining-xpcom-components.rst

@@ -102,6 +102,12 @@ Class definitions may have the following properties:
   
   This property is incompatible with ``legacy_constructor``.
 
+``jsm`` (optional)
+  If provided, must be the URL of a JavaScript module which contains a
+  JavaScript implementation of the component. The ``constructor`` property
+  must contain the name of an exported function which can be constructed to
+  create a new instance of the component.
+
 ``legacy_constructor`` (optional)
   This property is deprecated, and should not be used in new code.
   

xpcom/components/StaticComponents.cpp.in

@@ -9,8 +9,11 @@
 #include "mozilla/PerfectHash.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozJSComponentLoader.h"
 #include "nsCOMPtr.h"
 #include "nsComponentManager.h"
+#include "nsContentUtils.h"
 #include "nsIFactory.h"
 #include "nsISupports.h"
 #include "nsString.h"
@@ -27,6 +30,9 @@
 //# @decls@
 
 namespace mozilla {
+
+using dom::AutoJSAPI;
+
 namespace xpcom {
 
 static constexpr uint32_t kNoContractID = 0xffffffff;
@@ -83,6 +89,37 @@ bool ContractEntry::Matches(const nsACString& aContractID) const {
 }
 
 
+static nsresult ConstructJSMComponent(const nsACString& aURI,
+                                      const char* aConstructor,
+                                      nsISupports** aResult) {
+  if (!nsComponentManagerImpl::JSLoaderReady()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  AutoJSAPI jsapi;
+  MOZ_ALWAYS_TRUE(jsapi.Init(xpc::PrivilegedJunkScope()));
+  JSContext* cx = jsapi.cx();
+
+  JS::RootedObject global(cx);
+  JS::RootedObject exports(cx);
+  MOZ_TRY(mozJSComponentLoader::Get()->Import(cx, aURI, &global, &exports));
+
+  JS::RootedValue ctor(cx);
+  if (!JS_GetProperty(cx, exports, aConstructor, &ctor) ||
+      !ctor.isObject()) {
+    return NS_ERROR_XPC_JSOBJECT_HAS_NO_FUNCTION_NAMED;
+  }
+
+  JS::RootedObject inst(cx);
+  if (!JS::Construct(cx, ctor, JS::HandleValueArray::empty(), &inst)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return nsContentUtils::XPConnect()->WrapJS(cx, inst, NS_GET_IID(nsISupports),
+                                             (void**)aResult);
+}
+
+
 //# @module_cid_table@
 
 //# @module_contract_id_table@

xpcom/components/gen_static_components.py

@@ -218,6 +218,8 @@ class ModuleEntry(object):
         self.legacy_constructor = data.get('legacy_constructor', None)
         self.init_method = data.get('init_method', [])
 
+        self.jsm = data.get('jsm', None)
+
         self.external = data.get('external', not (self.headers or
                                                   self.legacy_constructor))
         self.singleton = data.get('singleton', False)
@@ -236,7 +238,15 @@ class ModuleEntry(object):
                 str(self.cid), ', '.join(map(repr, self.contract_ids)),
                 str_))
 
-        if self.external:
+        if self.jsm:
+            if not self.constructor:
+                error("JavaScript components must specify a constructor")
+
+            for prop in ('init_method', 'legacy_constructor', 'headers'):
+                if getattr(self, prop):
+                    error("JavaScript components may not specify a '%s' "
+                          "property" % prop)
+        elif self.external:
             if self.constructor or self.legacy_constructor:
                 error("Externally-constructed components may not specify "
                       "'constructor' or 'legacy_constructor' properties")
@@ -299,7 +309,14 @@ class ModuleEntry(object):
                     % self.legacy_constructor)
             return res
 
-        if self.external:
+        if self.jsm:
+            res += (
+                '      nsCOMPtr<nsISupports> inst;\n'
+                '      MOZ_TRY(ConstructJSMComponent(NS_LITERAL_CSTRING(%s),\n'
+                '                                    %s,\n'
+                '                                    getter_AddRefs(inst)));'
+                '\n' % (json.dumps(self.jsm), json.dumps(self.constructor)))
+        elif self.external:
             res += ('      nsCOMPtr<nsISupports> inst = '
                     'mozCreateComponent<%s>();\n' % self.type)
         else:

xpcom/components/nsComponentManager.cpp

@@ -531,6 +531,8 @@ nsresult nsComponentManagerImpl::Init() {
     // used, and before any calls are made into the JS engine.
     nsLayoutModuleInitialize();
 
+    mJSLoaderReady = true;
+
     // The overall order in which chrome.manifests are expected to be treated
     // is the following:
     // - greDir

xpcom/components/nsComponentManager.h

@@ -166,6 +166,8 @@ class nsComponentManagerImpl final : public nsIComponentManager,
   nsresult GetService(mozilla::xpcom::ModuleID, const nsIID& aIID,
                       void** aResult);
 
+  static bool JSLoaderReady() { return gComponentManager->mJSLoaderReady; }
+
   static void InitializeStaticModules();
   static void InitializeModuleLocations();
 
@@ -281,6 +283,8 @@ class nsComponentManagerImpl final : public nsIComponentManager,
 
   nsTArray<PendingServiceInfo> mPendingServices;
 
+  bool mJSLoaderReady = false;
+
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
  private: