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PEG and template system?

PostPosted: Mon Sep 15, 2014 8:20 pm
by newland
Hi,

I'm wondering, is there something like the PEG implementation of guile:

https://www.gnu.org/software/guile/docs ... rsing.html

That would allow to define templates and to define parsing rules for e.g. the wiki, without using regular expressions. Probably slower, but probably also easier to read.

thanks,

newland

Re: PEG and template system?

PostPosted: Mon Sep 15, 2014 10:05 pm
by TedWalther
Interesting. Are PEG related to the Scheme Regular Expressions that the Scheme crowd created a few years ago as the superior alternative to regular expressions?

http://srfi.schemers.org/srfi-115/srfi- ... l#Abstract

Or the Structural Regular Expressions designed by Rob Pike?

http://doc.cat-v.org/bell_labs/structur ... xps/se.pdf

Re: PEG and template system?

PostPosted: Tue Sep 16, 2014 9:13 am
by newland
Hi,

The scheme regex or Pike's system are not related to PEG's. A PEG is a top down parsing language, and you can use it to parse data or (small) command languages. A PEG often looks like a BNF , so making it quite easy to read and write. In contrast, simple regexes are easy to write and work fast, but complicated regexes are difficult to write and nearly impossible to decipher. Lua also has a quite nice PEG implementation.



https://en.wikipedia.org/wiki/Parsing_e ... on_grammar

https://en.wikipedia.org/wiki/Backus–Naur_Form

Re: PEG and template system?

PostPosted: Tue Sep 16, 2014 10:05 am
by newland
Hi,

forgot to add this link: http://www.inf.puc-rio.br/~roberto/docs/ry10-01.pdf on how to write regex equivalent in PEG. That article gives some motivation why PEG's are sometimes easier.

Re: PEG and template system?

PostPosted: Wed Sep 17, 2014 3:16 pm
by cormullion