Lexer and parser generators using CTFE

Christopher Bergqvist spambox0 at digitalpoetry.se
Wed Feb 29 15:04:08 PST 2012

On Wednesday, 29 February 2012 at 16:41:22 UTC, Andrei 
Alexandrescu wrote:
> On 2/28/12 7:16 PM, Christopher Bergqvist wrote:
>> What am I failing to pick up on?
> Barrier of entry and granularity of approach, I think.
> Currently if one wants to parse some simple grammar, there are 
> options such as (a) do it by hand, (b) use boost::spirit, or 
> (c) use lex/yacc.
> Parsing by hand has the obvious disadvantages. Using 
> boost::spirit has a steep learning curve and tends to create 
> very contorted grammar representations, full of representation 
> noise, and scales very poorly. Using lex/yacc is hamfisted - 
> there's an additional build step, generated files to deal with, 
> and the related logistics, which make lex/yacc a viable choice 
> only for "big" grammars.
> An efficient, integrated parser generator would lower the 
> barrier of entry dramatically - if we play our cards right, 
> even a sprintf specifier string could be parsed simpler and 
> faster using an embedded grammar, instead of painfully writing 
> the recognizer by hand. Parsing config files, XML, JSON, CSV, 
> various custom file formats and many others - all would all be 
> a few lines away. Ideally a user who has a basic understanding 
> of grammars should have an easier time using a small grammar to 
> parse simple custom formats, than writing the parsing code by 
> hand.
> Andrei

Thanks for your response.  The lowered barrier of entry in 
parsing something like a customized JSON format or config files 
is nice, and something I could see myself use.  I'm still 
skeptical about the level of "killer-featureness" but I would be 
glad to be proven wrong.

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