css securitylab & fop parser

2020-02-16 12:53:58 +01:00 · 2020-02-16 12:53:58 +01:00 · 1eadfe70da
commit 1eadfe70da
parent 7bbf3a5070
5 changed files with 283 additions and 0 deletions
--- a/infix-parser.rkt
+++ b/infix-parser.rkt
@ -0,0 +1,89 @@
+;; 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 infix-parser) (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])))
+
+
+
+
+
+
+
+(define (infix->prefix str)
+  (infix->prefix-expl (explode str)))
+
+(define (infix->prefix-expl lst)
+  (cond [(empty? (parse-add-sub lst)) empty]
+        [else (tree->prefix (first (parse-add-sub lst)))]))
+
+(define (parse-add-sub lst)
+  ((alt3 (seq3 parse-mul-div (accept-itm "+") parse-add-sub)
+         (seq3 parse-mul-div (accept-itm "-") parse-add-sub)
+         parse-mul-div) lst))
+
+(define (parse-mul-div lst)
+  ((alt3 (seq3 parse-number (accept-itm "*") parse-mul-div)
+         (seq3 parse-number (accept-itm "/") parse-mul-div)
+         parse-number) lst))
+
+(define parse-number (accept-digit))
+
+(define (tree->prefix tree)
+  (cond [(string? tree) tree]
+        [else (string-append (second tree)
+                             (tree->prefix (first tree))
+                             (tree->prefix (third tree)))]))