Add IsCallable method for Object in the API

test/cctest/test-api.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 7246 matching lines @@
     v8::Handle<Value> args[] = { v8_num(23) };
     value = instance->CallAsFunction(instance, 1, args);
     CHECK(try_catch.HasCaught());
     String::AsciiValue exception_value2(try_catch.Exception());
     CHECK_EQ("23", *exception_value2);
     try_catch.Reset();
   }
 }
 
 
+// Check whether a non-function object is callable.
+THREADED_TEST(CallableObject) {
+  v8::HandleScope scope;
+  LocalContext context;
+
+  { Local<ObjectTemplate> instance_template = ObjectTemplate::New();
+    instance_template->SetCallAsFunctionHandler(call_as_function);
+    Local<Object> instance = instance_template->NewInstance();
+    v8::TryCatch try_catch;
+
+    CHECK(instance->IsCallable());
+    CHECK(!try_catch.HasCaught());
+  }
+
+  { Local<ObjectTemplate> instance_template = ObjectTemplate::New();
+    Local<Object> instance = instance_template->NewInstance();
+    v8::TryCatch try_catch;
+
+    CHECK(!instance->IsCallable());
+    CHECK(!try_catch.HasCaught());
+  }
+
+  { Local<FunctionTemplate> function_template =
+        FunctionTemplate::New(call_as_function);
+    Local<Function> function = function_template->GetFunction();
+    Local<Object> instance = function;
+    v8::TryCatch try_catch;
+
+    CHECK(instance->IsCallable());
+    CHECK(!try_catch.HasCaught());
+  }
+
+  { Local<FunctionTemplate> function_template = FunctionTemplate::New();
+    Local<Function> function = function_template->GetFunction();
+    Local<Object> instance = function;
+    v8::TryCatch try_catch;
+
+    CHECK(instance->IsCallable());
+    CHECK(!try_catch.HasCaught());
+  }
+}
+
+
 static int CountHandles() {
   return v8::HandleScope::NumberOfHandles();
 }
 
 
 static int Recurse(int depth, int iterations) {
   v8::HandleScope scope;
   if (depth == 0) return CountHandles();
   for (int i = 0; i < iterations; i++) {
     Local<v8::Number> n = v8::Integer::New(42);
@@ skipping 7124 matching lines @@
 THREADED_TEST(CallAPIFunctionOnNonObject) {
   v8::HandleScope scope;
   LocalContext context;
   Handle<FunctionTemplate> templ = v8::FunctionTemplate::New(NonObjectThis);
   Handle<Function> function = templ->GetFunction();
   context->Global()->Set(v8_str("f"), function);
   TryCatch try_catch;
   CompileRun("f.call(2)");
   CHECK(try_catch.HasCaught());
 }