Start supporting fixed length and immutable lists.

dart/frog/leg/lib/js_helper.dart

Index: dart/frog/leg/lib/js_helper.dart
diff --git a/dart/frog/leg/lib/js_helper.dart b/dart/frog/leg/lib/js_helper.dart
index 6537d5e95d9884bee49e6b65fffdac33909f8222..6aed9ca3d35af26e8524050349f885e085d0a2d1 100644
--- a/dart/frog/leg/lib/js_helper.dart
+++ b/dart/frog/leg/lib/js_helper.dart
@@ -242,6 +242,7 @@ indexSet(var a, var index, var value) {
     if (index < 0 || index >= a.length) {
       throw new IndexOutOfRangeException(index);
     }
+    checkImmutable(a, 'indexed set');

[Lasse Reichstein Nielsen, 2012/02/24 11:08:41]

Seems it should be named "checkMutable" to match our other "check" methods.

[ahe, 2012/02/27 11:51:12]

Done.

     return JS("Object", @"$0[$1] = $2", a, index, value);
   }
   checkNull(a);
@@ -249,9 +250,16 @@ indexSet(var a, var index, var value) {
   return value;
 }
 
+checkImmutable(list, reason) {
+  if (JS('bool', @'!!($0.immutable$list)', list)) {
+    throw new UnsupportedOperationException(reason);
+  }
+}
+
 builtin$add$1(var receiver, var value) {
   checkNull(receiver);
   if (isJsArray(receiver)) {
+    checkFixedLength(receiver, 'add');
     JS("Object", @"$0.push($1)", receiver, value);
     return;
   }
@@ -261,6 +269,7 @@ builtin$add$1(var receiver, var value) {
 builtin$removeLast$0(var receiver) {
   checkNull(receiver);
   if (isJsArray(receiver)) {
+    checkFixedLength(receiver, 'removeLast');
     if (receiver.length === 0) throw new IndexOutOfRangeException(-1);
     return JS("Object", @"$0.pop()", receiver);
   }
@@ -291,6 +300,7 @@ builtin$set$length(receiver, newLength) {
     checkNull(newLength); // TODO(ahe): This is not specified but co19 tests it.
     if (newLength is !int) throw new IllegalArgumentException(newLength);
     if (newLength < 0) throw new IndexOutOfRangeException(newLength);
+    checkFixedLength(receiver, 'set length');
     JS('void', @"$0.length = $1", receiver, newLength);
   } else {
     UNINTERCEPTED(receiver.length = newLength);
@@ -298,6 +308,12 @@ builtin$set$length(receiver, newLength) {
   return newLength;
 }
 
+checkFixedLength(list, reason) {

[Lasse Reichstein Nielsen, 2012/02/24 11:08:41]

Also the opposite name here - whatever that would be, perhaps
"checkVariableLengthList".

I would prefer having different types for variable length lists and fixed length
lists (Vector?) at the library level, and if any subtype relation exists between
them, the variable length list should extend the fixed length list (which
should't be called anything with "fixed length", but should just not have any
methods that changes the length).

[ahe, 2012/02/27 11:51:12]

Done.
As we discussed in person: please file an RFE at dartbug.com.

+  if (JS('bool', @'!!($0.fixed$length)', list)) {
+    throw new UnsupportedOperationException(reason);
+  }
+}
+
 builtin$toString$0(var value) {
   if (JS("bool", @"typeof $0 == 'object'", value)) {
     if (isJsArray(value)) {
@@ -378,11 +394,13 @@ class Primitives {
   }
 
   static List newList(length) {
-    if (length == null) return JS("Object", @"new Array()");
+    if (length === null) return JS("Object", @"new Array()");
     if ((length is !int) || (length < 0)) {
       throw new IllegalArgumentException(length);
     }
-    return JS("Object", @"new Array($0)", length);
+    var result = JS("Object", @"new Array($0)", length);
+    JS('bool', @'$0.fixed$length = $1', result, true);

[Lasse Reichstein Nielsen, 2012/02/24 11:08:41]

How about using "void" as type for things where we know that we don't use the
result?
Also, why pass true as parameter instead of using the JS "true" literal?

[ahe, 2012/02/27 11:51:12]

I'll see if that works.
I don't want to make assumptions about how we represent true.

+    return result;
   }
 
   static num dateNow() => JS("num", @"Date.now()");
@@ -561,6 +579,7 @@ builtin$addAll$1(receiver, collection) {
   checkNull(receiver);
   if (!isJsArray(receiver)) return UNINTERCEPTED(receiver.addAll(collection));
 
+  checkFixedLength(receiver, 'addAll');

[floitsch, 2012/02/24 10:15:09]

No need. receiver add does this check for you.
But I'm ok with keeping it.

[ahe, 2012/02/27 11:51:12]

Done.

   // TODO(ahe): Use for-in when it is implemented correctly.
   var iterator = collection.iterator();
   while (iterator.hasNext()) {
@@ -572,6 +591,7 @@ builtin$addLast$1(receiver, value) {
   checkNull(receiver);
   if (!isJsArray(receiver)) return UNINTERCEPTED(receiver.addLast(value));
 
+  checkFixedLength(receiver, 'addLast');
   JS("Object", @"$0.push($1)", receiver, value);
 }
 
@@ -727,6 +747,7 @@ builtin$removeRange$2(receiver, start, length) {
   if (!isJsArray(receiver)) {
     return UNINTERCEPTED(receiver.removeRange(start, length));
   }
+  checkFixedLength(receiver, 'removeRange');
   if (length == 0) {
     return;
   }
@@ -764,6 +785,7 @@ builtin$setRange$4(receiver, start, length, from, startFrom) {
     return UNINTERCEPTED(receiver.setRange(start, length, from, startFrom));
   }
 
+  checkImmutable(receiver, 'indexed set');
   if (length === 0) return;
   checkNull(start); // TODO(ahe): This is not specified but co19 tests it.
   checkNull(length); // TODO(ahe): This is not specified but co19 tests it.
@@ -1196,3 +1218,9 @@ builtin$charCodes$0(receiver) {
   }
   return result;
 }
+
+makeLiteralListConst(list) {
+  JS('bool', @'$0.immutable$list = $1', list, true);
+  JS('bool', @'$0.fixed$length = $1', list, true);
+  return list;
+}