Promises: some adaptations to spec

src/promise.js

 // Copyright 2012 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 42 matching lines @@
 var promiseStatus = NEW_PRIVATE("Promise#status");
 var promiseValue = NEW_PRIVATE("Promise#value");
 var promiseOnResolve = NEW_PRIVATE("Promise#onResolve");
 var promiseOnReject = NEW_PRIVATE("Promise#onReject");
 var promiseRaw = NEW_PRIVATE("Promise#raw");
 
 function IsPromise(x) {
   return IS_SPEC_OBJECT(x) && %HasLocalProperty(x, promiseStatus);
 }
 
 function Promise(resolver) {

[yhirano, 2013/12/09 02:31:36]

I'm still not sure.
The spec has not been changed at this point, has it?

[rossberg, 2013/12/10 10:11:15]

No, but the spec requires that exceptions from the function itself are delayed,
so this CL makes it "more conforming" at least. An extra type check would be
needed to implement the synchronous type error.

[yhirano, 2013/12/11 04:46:31]

Then can you write a comment?

[rossberg, 2014/01/09 12:51:43]

Changed to throw

   if (resolver === promiseRaw) return;
+  if (!%_IsConstructCall()) throw MakeTypeError('not_a_promise', [this]);
   var promise = PromiseInit(this);
-  resolver(function(x) { PromiseResolve(promise, x) },
-           function(r) { PromiseReject(promise, r) });
-  // TODO(rossberg): current draft makes exception from this call asynchronous,
-  // but that's probably a mistake.
+  try {
+    resolver(function(x) { PromiseResolve(promise, x) },
+             function(r) { PromiseReject(promise, r) });
+  } catch (e) {
+    PromiseReject(promise, e);
+  }
 }
 
 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) return;
-  PromiseEnqueue(value, GET_PRIVATE(promise, promiseQueue));
-  PromiseSet(promise, status, value);
+  if (GET_PRIVATE(promise, promiseStatus) === 0) {
+    PromiseEnqueue(value, GET_PRIVATE(promise, promiseQueue));
+    PromiseSet(promise, status, value);
+  }
 }
 
 function PromiseResolve(promise, x) {
   PromiseDone(promise, +1, x, promiseOnResolve)
 }
 
 function PromiseReject(promise, r) {
   PromiseDone(promise, -1, r, promiseOnReject)
 }
 
@@ skipping 114 matching lines @@
       return x === that ? onReject(MakeTypeError('promise_cyclic', [x])) :
              IsPromise(x) ? x.then(onResolve, onReject) : onResolve(x);
     },
     onReject
   );
 }
 
 PromiseCoerce.table = new $WeakMap;
 
 function PromiseCoerce(constructor, x) {
-  var then;
-  if (IsPromise(x)) {
-    return x;
-  } else if (!IS_NULL_OR_UNDEFINED(x) && %IsCallable(then = x.then)) {
-    if (PromiseCoerce.table.has(x)) {
-      return PromiseCoerce.table.get(x);
-    } else {
-      var deferred = constructor.deferred();
-      PromiseCoerce.table.set(x, deferred.promise);
-      try {
-        %_CallFunction(x, deferred.resolve, deferred.reject, then);
-      } catch(e) {
-        deferred.reject(e);
+  if (!(IsPromise(x) || IS_NULL_OR_UNDEFINED(x))) {
+    var then = x.then;
+    if (typeof then === 'function') {
+      if (PromiseCoerce.table.has(x)) {
+        return PromiseCoerce.table.get(x);
+      } else {
+        var deferred = %_CallFunction(constructor, PromiseDeferred);
+        PromiseCoerce.table.set(x, deferred.promise);
+        try {
+          %_CallFunction(x, deferred.resolve, deferred.reject, then);
+        } catch(e) {
+          deferred.reject(e);
+        }
+        return deferred.promise;
       }
-      return deferred.promise;
     }
-  } else {
-    return x;
   }
+  return x;
 }
 
 
 // Combinators.
 
 function PromiseCast(x) {
   // TODO(rossberg): cannot do better until we support @@create.
-  return IsPromise(x) ? x : this.resolved(x);
+  return IsPromise(x) ? x : this.resolve(x);
 }
 
 function PromiseAll(values) {
-  var deferred = this.deferred();
+  var deferred = %_CallFunction(this, PromiseDeferred);
   var resolutions = [];
-  var count = values.length;
-  if (count === 0) {
-    deferred.resolve(resolutions);
-  } else {
-    for (var i = 0; i < values.length; ++i) {
-      this.cast(values[i]).chain(
-        function(i, x) {
-          resolutions[i] = x;
-          if (--count === 0) deferred.resolve(resolutions);
-        }.bind(UNDEFINED, i),  // TODO(rossberg): use let loop once available
-        function(r) {
-          if (count > 0) { count = 0; deferred.reject(r) }
-        }
-      );
+  try {
+    var count = values.length;
+    if (count === 0) {
+      deferred.resolve(resolutions);
+    } else {
+      for (var i = 0; i < values.length; ++i) {
+        this.cast(values[i]).chain(
+          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;
 }
 
 function PromiseOne(values) {  // a.k.a. race
-  var deferred = this.deferred();
-  var done = false;
-  for (var i = 0; i < values.length; ++i) {
-    this.cast(values[i]).chain(
-      function(x) { if (!done) { done = true; deferred.resolve(x) } },
-      function(r) { if (!done) { done = true; deferred.reject(r) } }
-    );
+  var deferred = %_CallFunction(this, PromiseDeferred);
+  try {
+    for (var i = 0; i < values.length; ++i) {
+      this.cast(values[i]).chain(
+        function(x) { deferred.resolve(x) },
+        function(r) { deferred.reject(r) }
+      );
+    }
+  } catch (e) {
+    deferred.reject(e)
   }
   return deferred.promise;
 }
 
 //-------------------------------------------------------------------
 
 function SetUpPromise() {
   %CheckIsBootstrapping()
   global.Promise = $Promise;
   InstallFunctions($Promise, DONT_ENUM, [
-    "deferred", PromiseDeferred,
-    "resolved", PromiseResolved,
-    "rejected", PromiseRejected,
+    "defer", PromiseDeferred,
+    "resolve", PromiseResolved,
+    "reject", PromiseRejected,
     "all", PromiseAll,
     "one", PromiseOne,

[arv (Not doing code reviews), 2013/12/10 14:21:24]

This should be race

[rossberg, 2014/01/09 12:51:43]

Done.

     "cast", PromiseCast
   ]);
   InstallFunctions($Promise.prototype, DONT_ENUM, [
     "chain", PromiseChain,
     "then", PromiseThen,
     "catch", PromiseCatch
   ]);
 }
 
 SetUpPromise();