dart:dom indexeddb idbcursorwithvalue does not have continueFunction method

[sethladd]

This is an unfortunate blocker.

IDBCursorWithValue (specified http://www.w3.org/TR/IndexedDB/#idl-def-IDBCursorWithValue) should extend IDBCursor.

The current dart:dom implementation does NOT extend IDBCursor, and therefore does NOT allow a user to call continueFunction()

[sethladd]

Apologies, it does extend _IDBCursorJs

However, the error I get from running a simple app is:

Uncaught TypeError: Object #<IDBCursorWithValue> has no method 'continueFunction'

[sethladd]

Changed the title to: "dart:dom indexeddb idbcursorwithvalue does not have continueFunction method".

[sethladd]

Sample IndexedDB code (this encounters the error): https://gist.github.com/1889118

displayItems(dom.IDBDatabase db) {
  dom.IDBTransaction txn = db.transaction(TODOS_STORE, dom.IDBTransaction.READ_ONLY);
  dom.IDBObjectStore objectStore = txn.objectStore(TODOS_STORE);
  dom.IDBRequest cursorRequest = objectStore.openCursor();
  cursorRequest.addEventListener("success", (e) {
    dom.IDBCursor cursor = e.target.result;
    if (cursor != null) {
      renderItem(cursor.value);
      cursor.continueFunction();
    }
  });
  cursorRequest.addEventListener('error', (e) {
    print("Could not open cursor: $e");
  });
}

[sethladd]

Here is the compiled JavaScript code (from the nightly Frog)

cursorRequest.addEventListener("success", $wrap_call$1((function (e) {
    var cursor = e.get$target().get$result();
    if (cursor != null) {
      renderItem(cursor.value);
      cursor.continueFunction();
    }
  })

You can the continueFunction isn't being translated to .continue()

[rakudrama]

This is my favourite function!

The wrapperless implementations are dropping the renaming of this special case on the floor. In the wrapping dom we had to generate cursor['continue'] since some JS implementations think that continue is a keyword.

Several things need to line up to get this to work. It is made more tricky because of the optional argument.

Option (1) is (1a) to implement 'renaming' i.e. teach Frog that lone identifiers in native strings are the real name

  void continueFunction([_IDBKeyJs key = null]) native 'continue';

(1b) teach Frog that some names need to be quoted and put in array syntax
(1c) make the generator spit out the identifier

Option (2) is to cruft up the generator with a table of a dozen or so native strings as replacements to the default action. We would generate

  void continueFunction([_IDBKeyJs key = null]) native '''
if (key == null) return this'continue';
return this'continue';
''';

I want to look more into option (1) since the compiler has much more information and the feature has other uses.

[DartBot]

This comment was originally written by ngeoffray@google.com

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Stephen, I think I'd favor option 2 to go with frog, but we definitely need something different for leg.

I think generating something like (that could even be a helper);
void continueFunction([key]) {
  Function f = JS("this['continue']");
  return key == null ? f(key) : f();
}

The compiler will have enough information to optimize that.

WDYT?

[sethladd]

Sounds like option 2 is under our control, and could get us over the hump. I'm concerned that option 1 would take too long.

[sethladd]

Looks like the new changes aren't being copied into the SDK's lib directory. I still see:

void continueFunction([_IDBKeyJs key = null]) native;

in ~/Code/Dart-git/dart/xcodebuild/Release_ia32/dart-sdk/lib/

However, when I deleted the Release_ia32/dart-sdk directory, and rebuilt with ./tools/build.py -m release

and rebuilt, I saw the changes. I think this is a separate bug for build process.

[sethladd]

Slight issue, if you have the following line of code:

dom.IDBCursorWithValue cursor = ...
cursor.continueFunction()

then the JavaScript is still cursor.continueFunction()

If you write:

var cursor = ...
cursor.continueFunction()

you will get:

cursor.continueFunction$0(); (which is correct)

Shouldn't IDBCursorWithValue work, as it extends IDBCursor?

[sethladd]

BTW, success! [once I deleted and rebuilt my SDK and changed to IDBCursor] Thanks!

[rakudrama]

Does the code from the first example in comment #­9 run?
cursor.continueFunction() should be fine as there should be definition of continueFunction (no $0) in the JS somewhere.

[sethladd]

Yes, it does, thanks Stephen. Both 'var cursor' and 'dom.IDBCursorWithValue cursor' work. This is great, thanks! I think we can close this.

[rakudrama]

Fixed. Code on github compiles and runs in unchecked mode.

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Added Fixed label.