[runtime] Rewrite Function.prototype.toString in C++.

src/js/v8natives.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // ----------------------------------------------------------------------------
 // Imports
@@ skipping 1234 matching lines @@
   "parseInt", GlobalParseInt,
   "parseFloat", GlobalParseFloat
 ]);
 
 %SetForceInlineFlag(NumberIsNaN);
 
 
 // ----------------------------------------------------------------------------
 // Function
 
-function NativeCodeFunctionSourceString(func) {
-  var name = %FunctionGetName(func);
-  if (name) {
-    // Mimic what KJS does.
-    return 'function ' + name + '() { [native code] }';
-  }
-
-  return 'function () { [native code] }';
-}
-
-function FunctionSourceString(func) {
-  if (!IS_FUNCTION(func)) {
-    throw MakeTypeError(kNotGeneric, 'Function.prototype.toString');
-  }
-
-  if (%FunctionHidesSource(func)) {
-    return NativeCodeFunctionSourceString(func);
-  }
-
-  var classSource = %ClassGetSourceCode(func);
-  if (IS_STRING(classSource)) {
-    return classSource;
-  }
-
-  var source = %FunctionGetSourceCode(func);
-  if (!IS_STRING(source)) {
-    return NativeCodeFunctionSourceString(func);
-  }
-
-  if (%FunctionIsArrow(func)) {
-    return source;
-  }
-
-  var name = %FunctionNameShouldPrintAsAnonymous(func)
-      ? 'anonymous'
-      : %FunctionGetName(func);
-
-  var isGenerator = %FunctionIsGenerator(func);
-  var head = %FunctionIsConciseMethod(func)
-      ? (isGenerator ? '*' : '')
-      : (isGenerator ? 'function* ' : 'function ');
-  return head + name + source;
-}
-
-
-function FunctionToString() {
-  return FunctionSourceString(this);
-}
-
-
 // ES6 9.2.3.2 Function.prototype.bind(thisArg , ...args)
 function FunctionBind(this_arg) { // Length is 1.
   if (!IS_CALLABLE(this)) throw MakeTypeError(kFunctionBind);
 
   var boundFunction = function () {
     // Poison .arguments and .caller, but is otherwise not detectable.
     "use strict";
     // This function must not use any object literals (Object, Array, RegExp),
     // since the literals-array is being used to store the bound data.
     if (!IS_UNDEFINED(new.target)) {
@@ skipping 91 matching lines @@
 
 
 // ----------------------------------------------------------------------------
 
 %SetCode(GlobalFunction, FunctionConstructor);
 %AddNamedProperty(GlobalFunction.prototype, "constructor", GlobalFunction,
                   DONT_ENUM);
 
 utils.InstallFunctions(GlobalFunction.prototype, DONT_ENUM, [
   "bind", FunctionBind,
-  "toString", FunctionToString
 ]);
 
 // ----------------------------------------------------------------------------
 // Iterator related spec functions.
 
 // ES6 7.4.1 GetIterator(obj, method)
 function GetIterator(obj, method) {
   if (IS_UNDEFINED(method)) {
     method = obj[iteratorSymbol];
   }
   if (!IS_CALLABLE(method)) {
     throw MakeTypeError(kNotIterable, obj);
   }
   var iterator = %_Call(method, obj);
   if (!IS_RECEIVER(iterator)) {
     throw MakeTypeError(kNotAnIterator, iterator);
   }
   return iterator;
 }
 
 // ----------------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
-  to.FunctionSourceString = FunctionSourceString;
   to.GetIterator = GetIterator;
   to.GetMethod = GetMethod;
   to.IsFinite = GlobalIsFinite;
   to.IsNaN = GlobalIsNaN;
   to.NewFunctionString = NewFunctionString;
   to.NumberIsNaN = NumberIsNaN;
   to.ObjectDefineProperties = ObjectDefineProperties;
   to.ObjectDefineProperty = ObjectDefineProperty;
   to.ObjectFreeze = ObjectFreezeJS;
   to.ObjectHasOwnProperty = ObjectHasOwnProperty;
   to.ObjectIsFrozen = ObjectIsFrozen;
   to.ObjectIsSealed = ObjectIsSealed;
   to.ObjectKeys = ObjectKeys;
 });
 
 %InstallToContext([
   "global_eval_fun", GlobalEval,
   "object_value_of", ObjectValueOf,
 ]);
 
 })