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|
; -*- Mode: Scheme; Syntax: Scheme; Package: Scheme; -*-
; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
; This is file write.scm.
;;;; WRITE
; To use this with some Scheme other than Scheme 48, do the following:
; 1. Copy the definition of output-port-option from port.scm
; 2. Define write-string as appropriate (as a write-char loop)
; 3. (define (disclose x) #f)
(define (write obj . port-option)
(let ((port (output-port-option port-option)))
(let recur ((obj obj))
(recurring-write obj port recur))))
(define (recurring-write obj port recur)
(cond ((null? obj) (write-string "()" port))
((pair? obj) (write-list obj port recur))
((eq? obj #t) (write-boolean 't port))
((eq? obj #f) (write-boolean 'f port))
((symbol? obj) (write-string (symbol->string obj) port))
((number? obj) (write-number obj port))
((string? obj) (write-string-literal obj port))
((char? obj) (write-char-literal obj port))
(else (write-other obj port recur))))
(define (write-boolean mumble port)
(write-char #\# port)
(write mumble port))
(define (write-number n port)
(write-string (number->string n 10) port))
(define (write-char-literal obj port)
(let ((probe (character-name obj)))
(write-string "#\\" port)
(if probe
(write probe port)
(write-char obj port))))
(define (character-name char)
(cond ((char=? char #\space) 'space)
((char=? char #\newline) 'newline)
(else #f)))
(define (write-string-literal obj port)
(write-char #\" port)
(let ((len (string-length obj)))
(do ((i 0 (+ i 1)))
((= i len) (write-char #\" port))
(let ((c (string-ref obj i)))
(if (or (char=? c #\\) (char=? c #\"))
(write-char #\\ port))
(write-char c port)))))
(define (write-list obj port recur)
(cond ((quotation? obj)
(write-char #\' port)
(recur (cadr obj)))
(else
(write-char #\( port)
(recur (car obj))
(let loop ((l (cdr obj))
(n 1))
(cond ((not (pair? l))
(cond ((not (null? l))
(write-string " . " port)
(recur l))))
(else
(write-char #\space port)
(recur (car l))
(loop (cdr l) (+ n 1)))))
(write-char #\) port))))
(define (quotation? obj)
(and (pair? obj)
(eq? (car obj) 'quote)
(pair? (cdr obj))
(null? (cddr obj))))
(define (write-vector obj port recur)
(write-string "#(" port)
(let ((z (vector-length obj)))
(cond ((> z 0)
(recur (vector-ref obj 0))
(let loop ((i 1))
(cond ((>= i z))
(else
(write-char #\space port)
(recur (vector-ref obj i))
(loop (+ i 1))))))))
(write-char #\) port))
; The vector case goes last just so that this version of WRITE can be
; used in Scheme implementations in which records, ports, or
; procedures are represented as vectors. (Scheme 48 doesn't have this
; property.)
(define (write-other obj port recur)
(cond ((disclose obj)
=> (lambda (l)
(write-string "#{" port)
(display-type-name (car l) port)
(for-each (lambda (x)
(write-char #\space port)
(recur x))
(cdr l))
(write-string "}" port)))
((eof-object? obj) (write-string "#{End-of-file}" port))
((vector? obj) (write-vector obj port recur))
((procedure? obj) (write-string "#{Procedure}" port))
(((structure-ref code-vectors code-vector?) obj)
(write-string "#{Byte-vector}" port))
(((structure-ref low-channels channel?) obj)
(write-string "#{Channel " port)
(display ((structure-ref low-channels channel-id) obj) port)
(write-string "}" port))
((eq? obj (if #f #f)) (write-string "#{Unspecific}" port))
(else
(write-string "#{Random object}" port))))
; Display the symbol WHO-CARES as Who-cares.
(define (display-type-name name port)
(if (symbol? name)
(let* ((s (symbol->string name))
(len (string-length s)))
(if (and (> len 0)
(char-alphabetic? (string-ref s 0)))
(begin (write-char (char-upcase (string-ref s 0)) port)
(do ((i 1 (+ i 1)))
((>= i len))
(write-char (char-downcase (string-ref s i)) port)))
(display name port)))
(display name port)))
;(define (write-string s port)
; (do ((i 0 (+ i 1)))
; ((= i (string-length s)))
; (write-char (string-ref s i) port)))
; DISPLAY
(define (display obj . port-option)
(let ((port (output-port-option port-option)))
(let recur ((obj obj))
(cond ((string? obj) (write-string obj port))
((char? obj) (write-char obj port))
(else
(recurring-write obj port recur))))))
|
