You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
brag/rules/stx.rkt

60 lines
2.9 KiB
Racket

#lang racket/base
(require yaragg/rules/rule-structs
racket/match)
(provide rule->stx)
(define (rule->stx source a-rule)
(define id-stx
(syntax-property
(datum->syntax #f
(string->symbol (lhs-id-val (rule-lhs a-rule)))
(list source
(pos-line (lhs-id-start (rule-lhs a-rule)))
(pos-col (lhs-id-start (rule-lhs a-rule)))
(pos-offset (lhs-id-start (rule-lhs a-rule)))
(and (and (number? (pos-offset (lhs-id-start (rule-lhs a-rule))))
(number? (pos-offset (lhs-id-end (rule-lhs a-rule)))))
(- (pos-offset (lhs-id-end (rule-lhs a-rule)))
(pos-offset (lhs-id-start (rule-lhs a-rule)))))))
'hide-or-splice-lhs-id (lhs-id-splice (rule-lhs a-rule))))
(define pattern-stx (pattern->stx source (rule-pattern a-rule)))
(define line (pos-line (rule-start a-rule)))
(define column (pos-col (rule-start a-rule)))
(define position (pos-offset (rule-start a-rule)))
(define span (and (and (number? (pos-offset (rule-start a-rule)))
(number? (pos-offset (rule-end a-rule))))
(- (pos-offset (rule-end a-rule))
(pos-offset (rule-start a-rule)))))
(datum->syntax #f
`(rule ,id-stx ,pattern-stx)
(list source line column position span)))
(define (pattern->stx source a-pattern)
(define (pat->srcloc source pat)
(match-define (pos offset line col) (pattern-start pat))
(define offset-end (pos-offset (pattern-end pat)))
(define span (and (number? offset) (number? offset-end) (- offset-end offset)))
(list source line col offset span))
(let loop ([a-pattern a-pattern] [hide-state #f])
(define (pat->stx val) (datum->syntax #f val (pat->srcloc source a-pattern)))
(define-values (pat hide)
(match a-pattern
[(struct pattern-id (start end val hide)) (values `(id ,(pat->stx (string->symbol val))) hide)]
[(struct pattern-lit (start end val hide)) (values `(lit ,(pat->stx val)) hide)]
[(struct pattern-token (start end val hide)) (values `(token ,(pat->stx (string->symbol val))) hide)]
;; propagate hide value of choice, repeat, and seq into subpatterns
;; use `(or hide-state hide)` to capture parent value
[(struct pattern-choice (start end vals hide))
(values `(choice ,@(map (λ (val) (loop val (or hide-state hide))) vals)) hide)]
[(struct pattern-repeat (start end min max val hide))
(values `(repeat ,min ,max ,(loop val (or hide-state hide))) hide)]
[(struct pattern-seq (start end vals hide))
(values `(seq ,@(map (λ (val) (loop val (or hide-state hide))) vals)) hide)]))
(syntax-property (pat->stx pat) 'hide (or hide-state hide))))