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sigil-peg

PEG (Parsing Expression Grammar) library for Sigil. Represent patterns as S-expressions with a capture stack for structured output. Inspired by Janet's PEG module.

Usage

(import (sigil peg))

;; Match a literal string
(peg/match '(seq "hello" " " "world") "hello world")
; => #<peg-match 0..11 ()>

;; Capture matched text
(peg-match-captures (peg/match '(<- (* (char-set char-alphabetic?))) "hello"))
; => ("hello")

;; Define a grammar with named rules
(define-grammar csv
  (main (* (seq 'field (? (seq "," 'field)) 'newline))
  (field (<- (+ (! ",") (! "\n") any-char)))
  (newline (/ "\n" (input-end))))

Pattern Language

Atomic: "literal", #\char, 'rule-ref, any-char, (char-range #\a #\z), (char-set char-alphabetic?)
Combinators: (seq p ...), (/ p ...), (* p), (+ p), (? p), (! p), (& p), (to p), (thru p), (between min max p)
Captures: (<- p), (<- p tag), (group p), (position), (constant val), (cmt p fn), (drop p), (backref tag), (replace p val)
Anchors: (line-start), (line-end), (input-start), (input-end)