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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Interesting article on ARG work
Date: Mon, 9 Apr 2018 19:45:26 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:51418
Date: 2018-04-09T19:45:26+03:00
List-Id: <comp.lang.ada>

On 18-04-09 19:30 , Dmitry A. Kazakov wrote:
> On 2018-04-09 18:12, Niklas Holsti wrote:
>
>> For example, the text
>>
>>      if Foo then
>>         Bar;
>> @   else
>> @      Baz;
>>      end if;
>>
>> would be parsed in four ways, according to the four combinations of
>> choices (enabled/disabled) for the two @ signs:
>
> [...]
>
> It is a trivial recursive-descent parser. "else" cannot follow "@",
> because there is no statement starting with "else". Full stop.
>
> You compile all code, always, taking choices at the stage of code
> generation. Simple as tooth powder.

I was only commenting on the inapplicability of a GLR parser for this 
problem.

You seem to be suggesting a specific way to use "@" to include/exclude 
entire statements (not text lines) from the effective code. Could you 
please make your suggestion explicit? For example, with regard to the 
need (or perhaps not) to have at least a "null;" statement in each branch.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .