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css securitylab & fop parser

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joachimschmidt557 2020-02-16 12:53:58 +01:00
parent 7bbf3a5070
commit 1eadfe70da
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parser-utils.rkt Normal file
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;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-advanced-reader.ss" "lang")((modname parser-utils) (read-case-sensitive #t) (teachpacks ((lib "gui.rkt" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "gui.rkt" "teachpack" "htdp")) #f)))
(define (alt2 parser1 parser2)
(lambda (lst)
(cond [(not (empty? (parser1 lst))) (parser1 lst)]
[else (parser2 lst)])))
(define (alt3 parser1 parser2 parser3)
(lambda (lst)
(cond [(not (empty? (parser1 lst))) (parser1 lst)]
[(not (empty? (parser2 lst))) (parser2 lst)]
[else (parser3 lst)])))
(define (seq2 parser1 parser2)
(lambda (lst)
(cond [(empty? (parser1 lst)) empty]
[(empty? (parser2 (second (parser1 lst)))) empty]
[else (list (list (first (parser1 lst))
(first (parser2 (second (parser1 lst)))))
(second (parser2 (second (parser1 lst)))))])))
(define (seq3 parser1 parser2 parser3)
(lambda (lst)
(cond [(empty? (parser1 lst)) empty]
[(empty? (parser2 (second (parser1 lst)))) empty]
[(empty? (parser3 (second (parser2 (second (parser1 lst)))))) empty]
[else (list (list (first (parser1 lst))
(first (parser2 (second (parser1 lst))))
(first (parser3 (second (parser2 (second (parser1 lst)))))))
(second (parser3 (second (parser2 (second (parser1 lst)))))))])))
(define (accept-itm itm)
(lambda (lst)
(cond [(empty? lst) empty]
[(equal? (first lst) itm) (list itm (rest lst))]
[else empty])))
(define (accept-digit)
(lambda (lst)
(cond [(empty? lst) empty]
[(or (equal? "0" (first lst))
(equal? "1" (first lst))
(equal? "2" (first lst))
(equal? "3" (first lst))
(equal? "4" (first lst))
(equal? "5" (first lst))
(equal? "6" (first lst))
(equal? "7" (first lst))
(equal? "8" (first lst))
(equal? "9" (first lst)))
(list (first lst) (rest lst))]
[else empty])))
(define (accept-empty)
(lambda (lst)
(cond [(empty? lst) (list empty empty)]
[else empty])))