text: // Copyright 2013 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
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  "use strict";
  
  // This file relies on the fact that the following declaration has been made
  // in runtime.js:
  // var $Array = global.Array;
  
  var $Symbol = global.Symbol;
  
  // -------------------------------------------------------------------
  
  function SymbolConstructor(x) {
    var value =
      IS_SYMBOL(x) ? x : %CreateSymbol(IS_UNDEFINED(x) ? x : ToString(x));
    if (%_IsConstructCall()) {
      %_SetValueOf(this, value);
    } else {
      return value;
    }
  }
  
  function SymbolGetName() {
    var symbol = IS_SYMBOL_WRAPPER(this) ? %_ValueOf(this) : this;
    if (!IS_SYMBOL(symbol)) {
      throw MakeTypeError(
          'incompatible_method_receiver', ["Symbol.prototype.name", this]);
    }
    return %SymbolName(symbol);
  }
  
  function SymbolToString() {
    throw MakeTypeError('symbol_to_string');
  }
  
  function SymbolValueOf() {
    // NOTE: Both Symbol objects and values can enter here as
    // 'this'. This is not as dictated by ECMA-262.
    if (!IS_SYMBOL(this) && !IS_SYMBOL_WRAPPER(this)) {
      throw MakeTypeError(
          'incompatible_method_receiver', ["Symbol.prototype.valueOf", this]);
    }
    return %_ValueOf(this);
  }
  
  
  // ES6 19.1.2.8
  function ObjectGetOwnPropertySymbols(obj) {
    if (!IS_SPEC_OBJECT(obj)) {
      throw MakeTypeError("called_on_non_object",
                          ["Object.getOwnPropertySymbols"]);
    }
  
    // TODO(arv): Proxies use a shared trap for String and Symbol keys.
  
    return ObjectGetOwnPropertyKeys(obj, true);
  }
  
  
  //-------------------------------------------------------------------
  
  function SetUpSymbol() {
    %CheckIsBootstrapping();
  
    %SetCode($Symbol, SymbolConstructor);
    %FunctionSetPrototype($Symbol, new $Symbol());
    %SetProperty($Symbol.prototype, "constructor", $Symbol, DONT_ENUM);
  
    InstallGetter($Symbol.prototype, "name", SymbolGetName);
    InstallFunctions($Symbol.prototype, DONT_ENUM, $Array(
      "toString", SymbolToString,
      "valueOf", SymbolValueOf
    ));
  }
  
  SetUpSymbol();
  
  
  function ExtendObject() {
    %CheckIsBootstrapping();
  
    InstallFunctions($Object, DONT_ENUM, $Array(
      "getOwnPropertySymbols", ObjectGetOwnPropertySymbols
    ));
  }
  
  ExtendObject();
  