RFR 8192974: overhaul descriptor string parsing

[Maurizio Cimadamore]

Whoops - forgot webrev:

http://cr.openjdk.java.net/~mcimadamore/8192974/

Maurizio


On 05/12/17 13:23, Maurizio Cimadamore wrote:
> Hi,
> this patch is a rewriting on the layout descriptor parser code - the 
> previous code was working correctly, but was a bit too convoluted and 
> lacked documentation. The new code is simpler and adds the grammar 
> productions in the javadoc of the various parsing methods. This work 
> should make it easier to add new features to the layout descriptor DSL 
> (such as symbolic references).
>
> The new parser has a single entry point - namely 'parseLayout', which 
> gives back a Stream<Type>.
>
> I've written a big test case that generates the set of sentences that 
> can be expressed in the descriptor grammar - of course since this set 
> is infinite, we need to do some tricks in order to prevent infinite 
> expansions of productions - and we also need to do some tricks not to 
> generate too many combinations.
>
> Currently, the test checks approx 7 millions different combinations - 
> and it does so in 10 seconds and with 1G of heap, which I think it's 
> acceptable.
>
> I also had to tweak the existing DescriptorTest as that was relying on 
> the structure of the old parser.
>
> Cheers
> Maurizio
>