comments for #lang peg

[rain-1]

We would like // comments.

[petrolifero]

change main.rkt, on the peg-port->scheme function, to :

"
(define (peg-port->scheme in)
(peg->scheme (car
(peg-result->object (peg (and peg (! (any-char))) (regexp-replace* "//[^\n]*" (port->string in) ""))))))
"

well, just put out the comments before processing. This will resolve, right?

[rain-1]

It would be slightly incorrect to strip comments this way, for example if // occured inside a string literal it would be treated as a comment.

For the optimal solution comment support needs to be added to https://github.com/rain-1/racket-peg/blob/master/peg-in-peg.rkt

[rain-1]

To achieve this I believe we would need to update the SP < [ \t\n]* ; rule to support the // comments.

After editing peg-in-peg.rkt the file https://github.com/rain-1/racket-peg/blob/master/peg-in-peg-expanded.rkt must be manually created by using the racket macro expander.

[petrolifero]

#lang peg

nt-char <- [a-zA-Z0-9_\-] ;
nonterminal <-- nt-char+ !nt-char SP ;
SP < [ \t\n]* ;

literal <-- SQ (BS ['\\] / !['\\] .)* SQ SP ;
SQ < ['] ;
BS < [\\] ;

charclass <-- LB '^'? (cc-range / cc-escape / cc-single)+ RB SP ;
cc-range <-- cc-char DASH cc-char ;
cc-escape <-- BS . ;
cc-single <-- cc-char ;
cc-char <- !cc-escape-char . ;
cc-escape-char <- '[' / ']' / '-' / '^' / '\\' / 'n' / 't' ;
LB < '[' ;
RB < ']' ;
DASH < '-' ;

peg <-- out grammar+ ;
grammar <-- (nonterminal ('<--' / '<-' / '<') SP pattern) ';' out ;
pattern <-- alternative (SLASH SP alternative)* ;
alternative <-- expression+ ;
expression <-- [!]? SP primary ([*+?] SP)? ;
primary <-- '(' SP pattern ')' SP / '.' SP / literal / charclass / nonterminal ;
SLASH < '/' ;



_ < ' ' / [\t] / [\n] ;
comment < '//' [^\n]* ;

out < (comment / _)* ;

I tested this and work. Can put comments in the end of a rule or between rules

//some comment
peg <-- a ; //another comment

//between

a < 'h' ; //end

//after

[petrolifero]

as a problem, I can't remove 'out' of the formed struct, probably because a misunderstanding of relation between < <- and <-- in diferente rules.

[rain-1]

Great! I've integrated this into the code, I added it to SP instead of creating out. It seems to be working but we should add a some comments to the examples to serve as tests.

3b41028
34bfe34

Thanks for contributing!

[rain-1]

• gotta add the new peg grammar to the docs

[rain-1]

f286257 make test working

1efda98 docs updated!

done!