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brag/br-parser-tools-lib/br-parser-tools/private-yacc/yacc-helper.rkt

72 lines
2.3 KiB
Racket

#lang racket/base
(require (prefix-in rl: racket/list)
"../private-lex/token-syntax.rkt")
;; General helper routines
(provide duplicate-list? remove-duplicates overlap? vector-andmap display-yacc)
(define (vector-andmap pred vec)
(for/and ([item (in-vector vec)])
(pred vec)))
;; duplicate-list?: symbol list -> #f | symbol
;; returns a symbol that exists twice in l, or false if no such symbol
;; exists
(define (duplicate-list? syms)
(rl:check-duplicates syms eq?))
;; remove-duplicates: syntax-object list -> syntax-object list
;; removes the duplicates from the lists
(define (remove-duplicates syms)
(rl:remove-duplicates syms equal? #:key syntax->datum))
;; overlap?: symbol list * symbol list -> #f | symbol
;; Returns an symbol in l1 intersect l2, or #f is no such symbol exists
(define (overlap? syms1 syms2)
(for/first ([sym1 (in-list syms1)]
#:when (memq sym1 syms2))
sym1))
(define (display-yacc grammar tokens start precs port)
(let-syntax ([p (syntax-rules ()
((_ args ...) (fprintf port args ...)))])
(let* ([tokens (map syntax-local-value tokens)]
[eterms (filter e-terminals-def? tokens)]
[terms (filter terminals-def? tokens)]
[term-table (make-hasheq)]
[display-rhs
(λ (rhs)
(for ([sym (in-list (car rhs))])
(p "~a " (hash-ref term-table sym (λ () sym))))
(when (= 3 (length rhs))
(p "%prec ~a" (cadadr rhs)))
(p "\n"))])
(for* ([t (in-list eterms)]
[t (in-list (syntax->datum (e-terminals-def-t t)))])
(hash-set! term-table t (format "'~a'" t)))
(for* ([t (in-list terms)]
[t (in-list (syntax->datum (terminals-def-t t)))])
(p "%token ~a\n" t)
(hash-set! term-table t (format "~a" t)))
(when precs
(for ([prec (in-list precs)])
(p "%~a " (car prec))
(for ([tok (in-list (cdr prec))])
(p " ~a" (hash-ref term-table tok)))
(p "\n")))
(p "%start ~a\n" start)
(p "%%\n")
(for ([prod (in-list grammar)])
(define nt (car prod))
(p "~a: " nt)
(display-rhs (cadr prod))
(for ([rhs (in-list (cddr prod))])
(p "| ")
(display-rhs rhs))
(p ";\n"))
(p "%%\n"))))