Here's a tutorial for small example of external lexing aka procedural
parsing:
http://jeffreykegler.github.io/Ocean-of-Awareness-blog/individual/2013/04/procedural.html


On Sat, Oct 15, 2016 at 4:12 AM, Harry <simonsha...@gmail.com> wrote:

> Thanks, Jeffrey, for your responses.
>
> I've gone through the documentation of Marpa::R2::Scanless::R
> <https://metacpan.org/pod/distribution/Marpa-R2/pod/Scanless/R.pod> but
> it's not becoming fully clear how to 'connect' the external lexing routine
> of mine to Marpa's built-in G1 parser. I've looked at some random Marpa
> code on the Net but that code is looking way too complicated as far as
> illustrating just the "external lexing" part goes.
>
> My expectation was (and, is) that of a bison/flex type of interface where
> yyparse() calls yylex() to get the next token following which things
> automatically work. With Marpa, it seems, you have to do (much?) more than
> that (sorry, if I'm being inaccurate here).
>
> What I already understand: When doing external lexing, I assume I'll have
> to create the equivalent of yylex() myself - in my case this function will,
> e.g., be making heavy use of Perl Regex's.
>
> However, how would I pass the string value returned by my yylex() to Marpa
> parser?
>
> Could someone please share a simple, "hello world" type of example, or if
> not that, at least some pseudocode?
>
>
> On Thursday, October 13, 2016 at 10:03:41 PM UTC+5:30, Jeffrey Kegler
> wrote:
>>
>> 4.) Not sure this answers your question, but L0 rules allow full Marpa
>> syntax.
>>
>
> May I ask, why the full Perl Regex syntax is not supported in L0 rules? If
> it were supported, I could've read a Java multi-line comment simply with
> just this one-liner:
> MultilineComment ~ ('/*' .*? '*/')   # parentheses being optional
>
>
> Regards,
> /Harry
>
>
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