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;;;; "qp.scm" Print finite length representation for any Scheme object.
;;; Copyright (C) 1991, 1992, 1993, 1995, 2003 Aubrey Jaffer
;
;Permission to copy this software, to modify it, to redistribute it,
;to distribute modified versions, and to use it for any purpose is
;granted, subject to the following restrictions and understandings.
;
;1. Any copy made of this software must include this copyright notice
;in full.
;
;2. I have made no warranty or representation that the operation of
;this software will be error-free, and I am under no obligation to
;provide any services, by way of maintenance, update, or otherwise.
;
;3. In conjunction with products arising from the use of this
;material, there shall be no use of my name in any advertising,
;promotional, or sales literature without prior written consent in
;each case.
;@
(define *qp-width* (output-port-width (current-output-port)))
;@
(define qp
(let
((+ +) (- -) (< <) (= =) (>= >=) (apply apply) (boolean? boolean?)
(car car) (cdr cdr) (char? char?) (display display) (eq? eq?)
(for-each for-each) (input-port? input-port?)
(not not) (null? null?) (number->string number->string)
(number? number?) (output-port? output-port?) (eof-object? eof-object?)
(procedure? procedure?) (string-length string-length)
(string? string?) (substring substring)
(symbol->string symbol->string) (symbol? symbol?)
(vector-length vector-length) (vector-ref vector-ref)
(vector? vector?) (write write) (quotient quotient))
(letrec
((num-cdrs
(lambda (pairs max-cdrs)
(cond
((null? pairs) 0)
((< max-cdrs 1) 1)
((pair? pairs) (+ 1 (num-cdrs (cdr pairs) (- max-cdrs 1))))
(else 1))))
(l-elt-room
(lambda (room pairs)
(quotient room (num-cdrs pairs (quotient room 8)))))
(qp-pairs
(lambda (cdrs room)
(cond
((null? cdrs) 0)
((not (pair? cdrs))
(display " . ")
(+ 3 (qp-obj cdrs (l-elt-room (- room 3) cdrs))))
((< 11 room)
(display #\space)
((lambda (used)
(+ (qp-pairs (cdr cdrs) (- room used)) used))
(+ 1 (qp-obj (car cdrs) (l-elt-room (- room 1) cdrs)))))
(else
(display " ...") 4))))
(v-elt-room
(lambda (room vleft)
(quotient room (min vleft (quotient room 8)))))
(qp-vect
(lambda (vect i room)
(cond
((= (vector-length vect) i) 0)
((< 11 room)
(display #\space)
((lambda (used)
(+ (qp-vect vect (+ i 1) (- room used)) used))
(+ 1 (qp-obj (vector-ref vect i)
(v-elt-room (- room 1)
(- (vector-length vect) i))))))
(else
(display " ...") 4))))
(qp-string
(lambda (str room)
(define len (string-length str))
(define mid (quotient (- room 3) 2))
(cond
((>= len room 3)
(display (substring str 0 (- room 3 mid)))
(display "...")
(display (substring str (- len mid) len))
room)
(else
(display str)
len))))
(qp-obj
(lambda (obj room)
(cond
((null? obj) (write obj) 2)
((boolean? obj) (write obj) 2)
((char? obj) (write obj) 8)
((number? obj) (qp-string (number->string obj) room))
((string? obj)
(display #\")
((lambda (ans) (display #\") ans)
(+ 2 (qp-string obj (- room 2)))))
((symbol? obj) (qp-string (symbol->string obj) room))
((input-port? obj) (display "#[input]") 8)
((output-port? obj) (display "#[output]") 9)
((procedure? obj) (display "#[proc]") 7)
((eof-object? obj) (display "#[eof]") 6)
((vector? obj)
(set! room (- room 3))
(display "#(")
((lambda (used) (display #\)) (+ used 3))
(cond
((= 0 (vector-length obj)) 0)
((< room 8) (display "...") 3)
(else
((lambda (used) (+ (qp-vect obj 1 (- room used)) used))
(qp-obj (vector-ref obj 0)
(v-elt-room room (vector-length obj))))))))
((pair? obj)
(set! room (- room 2))
(display #\()
((lambda (used) (display #\)) (+ 2 used))
(if (< room 8) (begin (display "...") 3)
((lambda (used)
(+ (qp-pairs (cdr obj) (- room used)) used))
(qp-obj (car obj) (l-elt-room room obj))))))
(else (display "#[unknown]") 10)))))
(lambda objs
(cond
((not *qp-width*)
(for-each (lambda (x) (write x) (display #\space)) objs)
(newline))
((= 0 *qp-width*)
(for-each (lambda (x)
(if (procedure? x) (display "#[proc]") (write x))
(display #\space)) objs))
(else
(qp-pairs (cdr objs)
(- *qp-width*
(qp-obj (car objs) (l-elt-room *qp-width* objs))))))))))
;@
(define qpn
(let ((newline newline) (apply apply) (qp qp))
(lambda objs (apply qp objs) (newline))))
;@
(define qpr
(let ((- -) (apply apply) (length length) (list-ref list-ref) (qpn qpn))
(lambda objs (apply qpn objs)
(list-ref objs (- (length objs) 1)))))
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