/usr/lib/draw-tree.scm is in scheme9 2013.11.26-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 | ; Scheme 9 from Empty Space, Function Library
; By Nils M Holm, 2009-2012
; Placed in the Public Domain
;
; (draw-tree object) ==> unspecific
;
; Print a tree structure resembling a Scheme datum. Each cons
; cell is represented by [o|o] with lines leading to their car
; and cdr parts. Conses with a cdr value of () are represented
; by [o|/].
;
; (Example): (draw-tree '((a) (b . c) (d e))) ==> unspecific
;
; Output: [o|o]---[o|o]---[o|/]
; | | |
; [o|/] | [o|o]---[o|/]
; | | | |
; a | d e
; |
; [o|o]--- c
; |
; b
(define (draw-tree n)
(define *nothing* (cons 'N '()))
(define *visited* (cons 'V '()))
(define (empty? x) (eq? x *nothing*))
(define (visited? x) (eq? (car x) *visited*))
(define (mark-visited x) (cons *visited* x))
(define (members-of x) (cdr x))
(define (done? x)
(and (pair? x)
(visited? x)
(null? (cdr x))))
(define (draw-fixed-string s)
(let* ((b (make-string 8 #\space))
(k (string-length s))
(s (if (> k 7) (substring s 0 7) s))
(s (if (< k 3) (string-append " " s) s))
(k (string-length s)))
(display (string-append s (substring b 0 (- 8 k))))))
(define (draw-atom n)
(cond ((null? n)
(draw-fixed-string "()"))
((symbol? n)
(draw-fixed-string (symbol->string n)))
((number? n)
(draw-fixed-string (number->string n)))
((string? n)
(draw-fixed-string (string-append "\"" n "\"")))
((char? n)
(draw-fixed-string (string-append "#\\" (string n))))
((eq? n #t)
(draw-fixed-string "#t"))
((eq? n #f)
(draw-fixed-string "#f"))
(else
(error "draw-atom: unknown type" n))))
(define (draw-conses n)
(let draw-conses ((n n)
(r '()))
(cond ((not (pair? n))
(draw-atom n)
(reverse! r))
((null? (cdr n))
(display "[o|/]")
(reverse! (cons (car n) r)))
(else
(display "[o|o]---")
(draw-conses (cdr n) (cons (car n) r))))))
(define (draw-bars n)
(let draw-bars ((n (members-of n)))
(cond ((not (pair? n)))
((empty? (car n))
(draw-fixed-string "")
(draw-bars (cdr n)))
((and (pair? (car n))
(visited? (car n)))
(draw-bars (members-of (car n)))
(draw-bars (cdr n)))
(else
(draw-fixed-string "|")
(draw-bars (cdr n))))))
(define (skip-empty n)
(if (and (pair? n)
(or (empty? (car n))
(done? (car n))))
(skip-empty (cdr n))
n))
(define (remove-trailing-nothing n)
(reverse (skip-empty (reverse n))))
(define (all-vertical? n)
(or (not (pair? n))
(and (null? (cdr n))
(all-vertical? (car n)))))
(define (draw-members n)
(let draw-members ((n (members-of n))
(r '()))
(cond ((not (pair? n))
(mark-visited
(remove-trailing-nothing
(reverse r))))
((empty? (car n))
(draw-fixed-string "")
(draw-members (cdr n)
(cons *nothing* r)))
((not (pair? (car n)))
(draw-atom (car n))
(draw-members (cdr n)
(cons *nothing* r)))
((null? (cdr n))
(draw-members (cdr n)
(cons (draw-final (car n)) r)))
((all-vertical? (car n))
(draw-fixed-string "[o|/]")
(draw-members (cdr n)
(cons (caar n) r)))
(else
(draw-fixed-string "|")
(draw-members (cdr n)
(cons (car n) r))))))
(define (draw-final n)
(cond ((not (pair? n))
(draw-atom n)
*nothing*)
((visited? n)
(draw-members n))
(else
(mark-visited (draw-conses n)))))
(if (not (pair? n))
(draw-atom n)
(let draw-tree ((n (mark-visited (draw-conses n))))
(if (not (done? n))
(begin (newline)
(draw-bars n)
(newline)
(draw-tree (draw-members n))))))
(newline))
(define dt draw-tree)
|