progress reporting and cancellation

[gavinking]

The converter is surprisingly slow (I wonder why?) and the problem with that is it locks up the IDE.

It should support progress reporting and cancellation via a ProgressMonitor-type construct.

[bjansen]

The parser is slow, not the actual converter.

On a random sample, the parser (parser.compilationUnit()) takes 89% of the time spent in the paste action. I was able to narrow it down to this method being called a lot (cumulating 76% of the total time), but I don't really know what to do with that. I'm not sure if it's something that can be fixed in ANTLR, or if we should try to change the grammar to make it more efficient.

[gavinking]

That's really strange. Our ANTLR-based Ceylon parser is way way faster.