Compiling Java 9

[Stephan Herrmann]

On 11/16/2016 11:57 PM, Alex Buckley wrote:
> On 11/16/2016 2:26 PM, Stephan Herrmann wrote:
>> And we may safely assume regularity of the grammar, i.e.,
>> the above approach will never lead to ambiguities, right?
>>
>> Fictitious counter example
>>
>>     ModuleDeclaration:
>>       module open Identifier ModuleBody;
>>       module Identifier ModuleBody;
>>
>> With this the second token could be keyword or identifier, and we're
>> stuck, aren't we?
>>
>> May we assume that the grammar will not be extended in such ambiguous ways?
>
> There is already a production like this:
>
> ModuleStatement:
>   requires transitive ModuleName ;
>   requires ModuleName ;

Outch!!

So when you read "requires transitive" which rule are you parsing against?
When do you decide whether transitive is a keyword or an identifier?
I guess we have to wait until we matched the full rule.
That requires backtracking, or what am I missing?

Stephan