Fix interface equality for undefined (js.Undefined).

dmitshur · dmitshur · commit cb553f393ba9 · 2015-06-07T20:41:27.000-07:00
Catch and handle the case of both values being js.Undefined in $interfaceIsEqual. Place this check underneath the check for (a.constructor !== b.constructor) as an optimization. Related to #237.
diff --git a/compiler/prelude/prelude.go b/compiler/prelude/prelude.go
@@ -413,6 +413,10 @@ var $interfaceIsEqual = function(a, b) {
   if (a.constructor !== b.constructor) {
     return false;
   }
+  if (a.constructor === $jsObjectPtr && a.object === undefined &&
+      b.constructor === $jsObjectPtr && b.object === undefined) {
+    return true;
+  }
   if (!a.constructor.comparable) {
     $throwRuntimeError("comparing uncomparable type " + a.constructor.string);
   }
diff --git a/js/js_test.go b/js/js_test.go
@@ -302,6 +302,13 @@ func TestEquality(t *testing.T) {
 	}
 }
 
+func TestUndefinedEquality(t *testing.T) {
+	var ui interface{} = js.Undefined
+	if ui != js.Undefined {
+		t.Fail()
+	}
+}
+
 func TestSameFuncWrapper(t *testing.T) {
 	a := func(_ string) {} // string argument to force wrapping
 	b := func(_ string) {} // string argument to force wrapping

Original file line number	Diff line number	Diff line change
`@@ -413,6 +413,10 @@ var $interfaceIsEqual = function(a, b) {`
`413`	`413`	`if (a.constructor !== b.constructor) {`
`414`	`414`	`return false;`
`415`	`415`	`}`
	`416`	`+ if (a.constructor === $jsObjectPtr && a.object === undefined &&`
	`417`	`+ b.constructor === $jsObjectPtr && b.object === undefined) {`
	`418`	`+ return true;`
	`419`	`+ }`
`416`	`420`	`if (!a.constructor.comparable) {`
`417`	`421`	`$throwRuntimeError("comparing uncomparable type " + a.constructor.string);`
`418`	`422`	`}`
Original file line number	Diff line number	Diff line change
`@@ -302,6 +302,13 @@ func TestEquality(t *testing.T) {`
`302`	`302`	`}`
`303`	`303`	`}`
`304`	`304`
	`305`	`+func TestUndefinedEquality(t *testing.T) {`
	`306`	`+ var ui interface{} = js.Undefined`
	`307`	`+ if ui != js.Undefined {`
	`308`	`+ t.Fail()`
	`309`	`+ }`
	`310`	`+}`
	`311`	`+`
`305`	`312`	`func TestSameFuncWrapper(t *testing.T) {`
`306`	`313`	`a := func(_ string) {} // string argument to force wrapping`
`307`	`314`	`b := func(_ string) {} // string argument to force wrapping`