toString() on generator functions prints with function*

This CL adds a %FunctionIsGenerator runtime function, and uses it in the
function toString() implementation.

R=mstarzinger@chromium.org
BUG=v8:2355
TEST=mjsunit/harmony/generators-runtime

Review URL: https://codereview.chromium.org/14912002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14544 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -2197,6 +2197,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionMarkNameShouldPrintAsAnonymous) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionIsGenerator) {
+  NoHandleAllocation ha(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSFunction, f, 0);
+  return isolate->heap()->ToBoolean(f->shared()->is_generator());
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionRemovePrototype) {
   NoHandleAllocation ha(isolate);
   ASSERT(args.length() == 1);

src/runtime.h

@@ -231,6 +231,7 @@ namespace internal {
   F(FunctionSetName, 2, 1) \
   F(FunctionNameShouldPrintAsAnonymous, 1, 1) \
   F(FunctionMarkNameShouldPrintAsAnonymous, 1, 1) \
+  F(FunctionIsGenerator, 1, 1) \
   F(FunctionBindArguments, 4, 1) \
   F(BoundFunctionGetBindings, 1, 1) \
   F(FunctionRemovePrototype, 1, 1) \

src/v8natives.js

@@ -1665,7 +1665,6 @@ function FunctionSourceString(func) {
     func = %GetCallTrap(func);
   }
 
-  // TODO(wingo): Print source using function* for generators.
   if (!IS_FUNCTION(func)) {
     throw new $TypeError('Function.prototype.toString is not generic');
   }
@@ -1684,7 +1683,8 @@ function FunctionSourceString(func) {
   var name = %FunctionNameShouldPrintAsAnonymous(func)
       ? 'anonymous'
       : %FunctionGetName(func);
-  return 'function ' + name + source;
+  var head = %FunctionIsGenerator(func) ? 'function* ' : 'function ';
+  return head + name + source;
 }
 
 

test/mjsunit/harmony/generators-runtime.js

@@ -105,6 +105,8 @@ function TestGeneratorFunction() {
   assertSame(Function, Object.getPrototypeOf(GeneratorFunction));
   assertTrue(g instanceof Function);
 
+  assertEquals("function* g() { yield 1; }", g.toString());
+
   // Not all functions are generators.
   assertTrue(f instanceof Function);  // Sanity check.
   assertTrue(!(f instanceof GeneratorFunction));