Harden a few builtins

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index d202f2886166af38985140786888831c0ba25be5..aa9da2e59495fd83610dac9fcb371f81ee7d6269 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -9,28 +9,18 @@
 // var $Object = global.Object
 // var $WeakMap = global.WeakMap
 
+// For bootstrapper.
 
-var $Promise = function Promise(resolver) {
-  if (resolver === promiseRaw) return;
-  if (!%_IsConstructCall()) throw MakeTypeError('not_a_promise', [this]);
-  if (!IS_SPEC_FUNCTION(resolver))
-    throw MakeTypeError('resolver_not_a_function', [resolver]);
-  var promise = PromiseInit(this);
-  try {
-    %DebugPromiseHandlePrologue(function() { return promise });
-    resolver(function(x) { PromiseResolve(promise, x) },
-             function(r) { PromiseReject(promise, r) });
-  } catch (e) {
-    PromiseReject(promise, e);
-  } finally {
-    %DebugPromiseHandleEpilogue();
-  }
-}
-
-
-//-------------------------------------------------------------------
+var IsPromise;
+var PromiseCreate;
+var PromiseResolve;
+var PromiseReject;
+var PromiseChain;
+var PromiseCatch;
 
-// Core functionality.
+// mirror-debugger.js currently uses builtins.promiseStatus. It would be nice
+// if we could move these property names into the closure below.
+// TODO(jkummerow/rossberg/yangguo): Find a better solution.
 
 // Status values: 0 = pending, +1 = resolved, -1 = rejected
 var promiseStatus = GLOBAL_PRIVATE("Promise#status");
@@ -39,250 +29,274 @@ var promiseOnResolve = GLOBAL_PRIVATE("Promise#onResolve");
 var promiseOnReject = GLOBAL_PRIVATE("Promise#onReject");
 var promiseRaw = GLOBAL_PRIVATE("Promise#raw");
 
-function IsPromise(x) {
-  return IS_SPEC_OBJECT(x) && %HasLocalProperty(x, promiseStatus);
-}
-
-function PromiseSet(promise, status, value, onResolve, onReject) {
-  SET_PRIVATE(promise, promiseStatus, status);
-  SET_PRIVATE(promise, promiseValue, value);
-  SET_PRIVATE(promise, promiseOnResolve, onResolve);
-  SET_PRIVATE(promise, promiseOnReject, onReject);
-  return promise;
-}
-
-function PromiseInit(promise) {
-  return PromiseSet(promise, 0, UNDEFINED, new InternalArray, new InternalArray)
-}
-
-function PromiseDone(promise, status, value, promiseQueue) {
-  if (GET_PRIVATE(promise, promiseStatus) === 0) {
-    PromiseEnqueue(value, GET_PRIVATE(promise, promiseQueue));
-    PromiseSet(promise, status, value);
+(function() {
+
+  var $Promise = function Promise(resolver) {
+    if (resolver === promiseRaw) return;
+    if (!%_IsConstructCall()) throw MakeTypeError('not_a_promise', [this]);
+    if (!IS_SPEC_FUNCTION(resolver))
+      throw MakeTypeError('resolver_not_a_function', [resolver]);
+    var promise = PromiseInit(this);
+    try {
+      %DebugPromiseHandlePrologue(function() { return promise });
+      resolver(function(x) { PromiseResolve(promise, x) },
+               function(r) { PromiseReject(promise, r) });
+    } catch (e) {
+      PromiseReject(promise, e);
+    } finally {
+      %DebugPromiseHandleEpilogue();
+    }
   }
-}
 
-function PromiseResolve(promise, x) {
-  PromiseDone(promise, +1, x, promiseOnResolve)
-}
+  // Core functionality.
 
-function PromiseReject(promise, r) {
-  PromiseDone(promise, -1, r, promiseOnReject)
-}
+  function PromiseSet(promise, status, value, onResolve, onReject) {
+    SET_PRIVATE(promise, promiseStatus, status);
+    SET_PRIVATE(promise, promiseValue, value);
+    SET_PRIVATE(promise, promiseOnResolve, onResolve);
+    SET_PRIVATE(promise, promiseOnReject, onReject);
+    return promise;
+  }
 
+  function PromiseInit(promise) {
+    return PromiseSet(promise, 0, UNDEFINED, new InternalArray,
+                      new InternalArray)
+  }
 
-// For API.
+  function PromiseDone(promise, status, value, promiseQueue) {
+    if (GET_PRIVATE(promise, promiseStatus) === 0) {
+      PromiseEnqueue(value, GET_PRIVATE(promise, promiseQueue));
+      PromiseSet(promise, status, value);
+    }
+  }
 
-function PromiseNopResolver() {}
+  function PromiseCoerce(constructor, x) {
+    if (!IsPromise(x) && IS_SPEC_OBJECT(x)) {
+      var then;
+      try {
+        then = x.then;
+      } catch(r) {
+        return %_CallFunction(constructor, r, PromiseRejected);
+      }
+      if (IS_SPEC_FUNCTION(then)) {
+        var deferred = %_CallFunction(constructor, PromiseDeferred);
+        try {
+          %_CallFunction(x, deferred.resolve, deferred.reject, then);
+        } catch(r) {
+          deferred.reject(r);
+        }
+        return deferred.promise;
+      }
+    }
+    return x;
+  }
 
-function PromiseCreate() {
-  return new $Promise(PromiseNopResolver)
-}
+  function PromiseHandle(value, handler, deferred) {
+    try {
+      %DebugPromiseHandlePrologue(
+          function() {
+            var queue = GET_PRIVATE(deferred.promise, promiseOnReject);
+            return (queue && queue.length == 0) ? deferred.promise : UNDEFINED;
+          });
+      var result = handler(value);
+      if (result === deferred.promise)
+        throw MakeTypeError('promise_cyclic', [result]);
+      else if (IsPromise(result))
+        %_CallFunction(result, deferred.resolve, deferred.reject, PromiseChain);
+      else
+        deferred.resolve(result);
+    } catch (exception) {
+      try {
+        %DebugPromiseHandlePrologue(function() { return deferred.promise });
+        deferred.reject(exception);
+      } catch (e) { } finally {
+        %DebugPromiseHandleEpilogue();
+      }
+    } finally {
+      %DebugPromiseHandleEpilogue();
+    }
+  }
+
+  function PromiseEnqueue(value, tasks) {
+    %EnqueueMicrotask(function() {
+      for (var i = 0; i < tasks.length; i += 2) {
+        PromiseHandle(value, tasks[i], tasks[i + 1])
+      }
+    });
+  }
 
+  function PromiseIdResolveHandler(x) { return x }
+  function PromiseIdRejectHandler(r) { throw r }
 
-// Convenience.
+  function PromiseNopResolver() {}
 
-function PromiseDeferred() {
-  if (this === $Promise) {
-    // Optimized case, avoid extra closure.
-    var promise = PromiseInit(new $Promise(promiseRaw));
-    return {
-      promise: promise,
-      resolve: function(x) { PromiseResolve(promise, x) },
-      reject: function(r) { PromiseReject(promise, r) }
-    };
-  } else {
-    var result = {};
-    result.promise = new this(function(resolve, reject) {
-      result.resolve = resolve;
-      result.reject = reject;
-    })
-    return result;
-  }
-}
-
-function PromiseResolved(x) {
-  if (this === $Promise) {
-    // Optimized case, avoid extra closure.
-    return PromiseSet(new $Promise(promiseRaw), +1, x);
-  } else {
-    return new this(function(resolve, reject) { resolve(x) });
+  // -------------------------------------------------------------------
+  // Define exported functions.
+
+  // For bootstrapper.
+
+  IsPromise = function IsPromise(x) {
+    return IS_SPEC_OBJECT(x) && %HasLocalProperty(x, promiseStatus);
   }
-}
-
-function PromiseRejected(r) {
-  if (this === $Promise) {
-    // Optimized case, avoid extra closure.
-    return PromiseSet(new $Promise(promiseRaw), -1, r);
-  } else {
-    return new this(function(resolve, reject) { reject(r) });
+
+  PromiseCreate = function PromiseCreate() {
+    return new $Promise(PromiseNopResolver)
   }
-}
-
-
-// Simple chaining.
-
-function PromiseIdResolveHandler(x) { return x }
-function PromiseIdRejectHandler(r) { throw r }
-
-function PromiseChain(onResolve, onReject) {  // a.k.a.  flatMap
-  onResolve = IS_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
-  onReject = IS_UNDEFINED(onReject) ? PromiseIdRejectHandler : onReject;
-  var deferred = %_CallFunction(this.constructor, PromiseDeferred);
-  switch (GET_PRIVATE(this, promiseStatus)) {
-    case UNDEFINED:
-      throw MakeTypeError('not_a_promise', [this]);
-    case 0:  // Pending
-      GET_PRIVATE(this, promiseOnResolve).push(onResolve, deferred);
-      GET_PRIVATE(this, promiseOnReject).push(onReject, deferred);
-      break;
-    case +1:  // Resolved
-      PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onResolve, deferred]);
-      break;
-    case -1:  // Rejected
-      PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onReject, deferred]);
-      break;
+
+  PromiseResolve = function PromiseResolve(promise, x) {
+    PromiseDone(promise, +1, x, promiseOnResolve)
   }
-  return deferred.promise;
-}
 
-function PromiseCatch(onReject) {
-  return this.then(UNDEFINED, onReject);
-}
+  PromiseReject = function PromiseReject(promise, r) {
+    PromiseDone(promise, -1, r, promiseOnReject)
+  }
 
-function PromiseEnqueue(value, tasks) {
-  %EnqueueMicrotask(function() {
-    for (var i = 0; i < tasks.length; i += 2) {
-      PromiseHandle(value, tasks[i], tasks[i + 1])
+  // Convenience.
+
+  function PromiseDeferred() {
+    if (this === $Promise) {
+      // Optimized case, avoid extra closure.
+      var promise = PromiseInit(new $Promise(promiseRaw));
+      return {
+        promise: promise,
+        resolve: function(x) { PromiseResolve(promise, x) },
+        reject: function(r) { PromiseReject(promise, r) }
+      };
+    } else {
+      var result = {};
+      result.promise = new this(function(resolve, reject) {
+        result.resolve = resolve;
+        result.reject = reject;
+      })
+      return result;
     }
-  });
-}
-
-function PromiseHandle(value, handler, deferred) {
-  try {
-    %DebugPromiseHandlePrologue(
-        function() {
-          var queue = GET_PRIVATE(deferred.promise, promiseOnReject);
-          return (queue && queue.length == 0) ? deferred.promise : UNDEFINED;
-        });
-    var result = handler(value);
-    if (result === deferred.promise)
-      throw MakeTypeError('promise_cyclic', [result]);
-    else if (IsPromise(result))
-      %_CallFunction(result, deferred.resolve, deferred.reject, PromiseChain);
-    else
-      deferred.resolve(result);
-  } catch (exception) {
-    try {
-      %DebugPromiseHandlePrologue(function() { return deferred.promise });
-      deferred.reject(exception);
-    } catch (e) { } finally {
-      %DebugPromiseHandleEpilogue();
+  }
+
+  function PromiseResolved(x) {
+    if (this === $Promise) {
+      // Optimized case, avoid extra closure.
+      return PromiseSet(new $Promise(promiseRaw), +1, x);
+    } else {
+      return new this(function(resolve, reject) { resolve(x) });
     }
-  } finally {
-    %DebugPromiseHandleEpilogue();
   }
-}
-
-
-// Multi-unwrapped chaining with thenable coercion.
-
-function PromiseThen(onResolve, onReject) {
-  onResolve = IS_SPEC_FUNCTION(onResolve) ? onResolve : PromiseIdResolveHandler;
-  onReject = IS_SPEC_FUNCTION(onReject) ? onReject : PromiseIdRejectHandler;
-  var that = this;
-  var constructor = this.constructor;
-  return %_CallFunction(
-    this,
-    function(x) {
-      x = PromiseCoerce(constructor, x);
-      return x === that ? onReject(MakeTypeError('promise_cyclic', [x])) :
-             IsPromise(x) ? x.then(onResolve, onReject) : onResolve(x);
-    },
-    onReject,
-    PromiseChain
-  );
-}
-
-function PromiseCoerce(constructor, x) {
-  if (!IsPromise(x) && IS_SPEC_OBJECT(x)) {
-    var then;
-    try {
-      then = x.then;
-    } catch(r) {
-      return %_CallFunction(constructor, r, PromiseRejected);
+
+  function PromiseRejected(r) {
+    if (this === $Promise) {
+      // Optimized case, avoid extra closure.
+      return PromiseSet(new $Promise(promiseRaw), -1, r);
+    } else {
+      return new this(function(resolve, reject) { reject(r) });
     }
-    if (IS_SPEC_FUNCTION(then)) {
-      var deferred = %_CallFunction(constructor, PromiseDeferred);
-      try {
-        %_CallFunction(x, deferred.resolve, deferred.reject, then);
-      } catch(r) {
-        deferred.reject(r);
-      }
-      return deferred.promise;
+  }
+
+  // Simple chaining.
+
+  PromiseChain = function PromiseChain(onResolve, onReject) {  // a.k.a.
+                                                                // flatMap
+    onResolve = IS_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
+    onReject = IS_UNDEFINED(onReject) ? PromiseIdRejectHandler : onReject;
+    var deferred = %_CallFunction(this.constructor, PromiseDeferred);
+    switch (GET_PRIVATE(this, promiseStatus)) {
+      case UNDEFINED:
+        throw MakeTypeError('not_a_promise', [this]);
+      case 0:  // Pending
+        GET_PRIVATE(this, promiseOnResolve).push(onResolve, deferred);
+        GET_PRIVATE(this, promiseOnReject).push(onReject, deferred);
+        break;
+      case +1:  // Resolved
+        PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onResolve, deferred]);
+        break;
+      case -1:  // Rejected
+        PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onReject, deferred]);
+        break;
     }
+    return deferred.promise;
   }
-  return x;
-}
 
+  PromiseCatch = function PromiseCatch(onReject) {
+    return this.then(UNDEFINED, onReject);
+  }
 
-// Combinators.
+  // Multi-unwrapped chaining with thenable coercion.
+
+  function PromiseThen(onResolve, onReject) {
+    onResolve = IS_SPEC_FUNCTION(onResolve) ? onResolve
+                                            : PromiseIdResolveHandler;
+    onReject = IS_SPEC_FUNCTION(onReject) ? onReject
+                                          : PromiseIdRejectHandler;
+    var that = this;
+    var constructor = this.constructor;
+    return %_CallFunction(
+      this,
+      function(x) {
+        x = PromiseCoerce(constructor, x);
+        return x === that ? onReject(MakeTypeError('promise_cyclic', [x])) :
+               IsPromise(x) ? x.then(onResolve, onReject) : onResolve(x);
+      },
+      onReject,
+      PromiseChain
+    );
+  }
 
-function PromiseCast(x) {
-  // TODO(rossberg): cannot do better until we support @@create.
-  return IsPromise(x) ? x : new this(function(resolve) { resolve(x) });
-}
+  // Combinators.
 
-function PromiseAll(values) {
-  var deferred = %_CallFunction(this, PromiseDeferred);
-  var resolutions = [];
-  if (!%_IsArray(values)) {
-    deferred.reject(MakeTypeError('invalid_argument'));
+  function PromiseCast(x) {
+    // TODO(rossberg): cannot do better until we support @@create.
+    return IsPromise(x) ? x : new this(function(resolve) { resolve(x) });
+  }
+
+  function PromiseAll(values) {
+    var deferred = %_CallFunction(this, PromiseDeferred);
+    var resolutions = [];
+    if (!%_IsArray(values)) {
+      deferred.reject(MakeTypeError('invalid_argument'));
+      return deferred.promise;
+    }
+    try {
+      var count = values.length;
+      if (count === 0) {
+        deferred.resolve(resolutions);
+      } else {
+        for (var i = 0; i < values.length; ++i) {
+          this.resolve(values[i]).then(
+            function(i, x) {
+              resolutions[i] = x;
+              if (--count === 0) deferred.resolve(resolutions);
+            }.bind(UNDEFINED, i),  // TODO(rossberg): use let loop once
+                                    // available
+            function(r) { deferred.reject(r) }
+          );
+        }
+      }
+    } catch (e) {
+      deferred.reject(e)
+    }
     return deferred.promise;
   }
-  try {
-    var count = values.length;
-    if (count === 0) {
-      deferred.resolve(resolutions);
-    } else {
+
+  function PromiseOne(values) {
+    var deferred = %_CallFunction(this, PromiseDeferred);
+    if (!%_IsArray(values)) {
+      deferred.reject(MakeTypeError('invalid_argument'));
+      return deferred.promise;
+    }
+    try {
       for (var i = 0; i < values.length; ++i) {
         this.resolve(values[i]).then(
-          function(i, x) {
-            resolutions[i] = x;
-            if (--count === 0) deferred.resolve(resolutions);
-          }.bind(UNDEFINED, i),  // TODO(rossberg): use let loop once available
+          function(x) { deferred.resolve(x) },
           function(r) { deferred.reject(r) }
         );
       }
+    } catch (e) {
+      deferred.reject(e)
     }
-  } catch (e) {
-    deferred.reject(e)
-  }
-  return deferred.promise;
-}
-
-function PromiseOne(values) {
-  var deferred = %_CallFunction(this, PromiseDeferred);
-  if (!%_IsArray(values)) {
-    deferred.reject(MakeTypeError('invalid_argument'));
     return deferred.promise;
   }
-  try {
-    for (var i = 0; i < values.length; ++i) {
-      this.resolve(values[i]).then(
-        function(x) { deferred.resolve(x) },
-        function(r) { deferred.reject(r) }
-      );
-    }
-  } catch (e) {
-    deferred.reject(e)
-  }
-  return deferred.promise;
-}
 
-//-------------------------------------------------------------------
+  // -------------------------------------------------------------------
+  // Install exported functions.
 
-function SetUpPromise() {
   %CheckIsBootstrapping();
   %SetProperty(global, 'Promise', $Promise, DONT_ENUM);
   InstallFunctions($Promise, DONT_ENUM, [
@@ -298,6 +312,5 @@ function SetUpPromise() {
     "then", PromiseThen,
     "catch", PromiseCatch
   ]);
-}
 
-SetUpPromise();
+})();