Guile-hoot/module/hoot/write.scm

;;; (hoot write) library
;;; Copyright (C) 2024 Igalia, S.L.
;;;
;;; Licensed under the Apache License, Version 2.0 (the "License");
;;; you may not use this file except in compliance with the License.
;;; You may obtain a copy of the License at
;;;
;;;    http://www.apache.org/licenses/LICENSE-2.0
;;;
;;; Unless required by applicable law or agreed to in writing, software
;;; distributed under the License is distributed on an "AS IS" BASIS,
;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;; See the License for the specific language governing permissions and
;;; limitations under the License.

;;; Commentary:
;;;
;;; R7RS (scheme write) implementation, plus number->string
;;;
;;; Code:

(library (hoot write)
  (export number->string
          display write write-shared write-simple)
  (import (hoot primitives)
    (hoot errors)
    (hoot bitwise)
    (hoot bitvectors)
    (hoot bytevectors)
    (hoot char)
    (hoot keywords)
    (hoot procedures)
    (hoot strings)
    (hoot symbols)
    (hoot numbers)
    (hoot vectors)
    (hoot ports)
    (only (hoot records)
          record? write-record)
    (hoot pairs)
    (hoot eq))

(define* (number->string n #:optional (radix 10))
  (cond
   ((exact-integer? n)
    (if (zero? n)
        "0"
        (let* ((mag (if (< n 0) (- n) n))
               (digits
                (case radix
                  ((2) (let lp ((mag mag) (out '()))
                         (if (zero? mag)
                             out
                             (lp (ash mag -1)
                                 (cons (integer->char
                                        (+ (char->integer #\0)
                                           (logand mag 1)))
                                       out)))))
                  ((8) (let lp ((mag mag) (out '()))
                         (if (zero? mag)
                             out
                             (lp (ash mag -3)
                                 (cons (integer->char
                                        (+ (char->integer #\0)
                                           (logand mag 7)))
                                       out)))))
                  ((10) (let lp ((mag mag) (out '()))
                          (if (zero? mag)
                              out
                              (lp (quotient mag 10)
                                  (cons (integer->char
                                         (+ (char->integer #\0)
                                            (remainder mag 10)))
                                        out)))))
                  ((16) (let lp ((mag mag) (out '()))
                          (if (zero? mag)
                              out
                              (lp (ash mag -4)
                                  (cons (integer->char
                                         (let ((digit (logand mag 15)))
                                           (+ (if (< digit 10)
                                                  (char->integer #\0)
                                                  (char->integer #\a))
                                              digit)))
                                        out))))))))
          (list->string (if (negative? n) (cons #\- digits) digits)))))
   ((exact? n)
    (string-append (number->string (numerator n) radix)
                   "/"
                   (number->string (denominator n) radix)))
   ((real? n)
    (assert (eqv? radix 10) 'number->string)
    (%inline-wasm
     '(func (param $n f64)
            (result (ref eq))
            (struct.new $string
                        (i32.const 0)
                        (call $flonum->string (local.get $n))))
     n))
   (else
    (string-append (number->string (real-part n) radix)
                   "/"
                   (number->string (imag-part n) radix)
                   "i"))))

  (define* (%write-datum port x #:optional quote-strings?)
    (define (recur x) (%write-datum port x quote-strings?))
    (cond
     ((eq? x #f)         (write-string "#f" port))
     ((eq? x #t)         (write-string "#t" port))
     ((eq? x #nil)       (write-string "#nil" port))
     ((eq? x '())        (write-string "()" port))
     ((eq? x (if #f #f)) (write-string "#<unspecified>" port))
     ((eof-object? x)    (write-string "#<eof>" port))
     ((number? x)        (write-string (number->string x) port))
     ((char? x)
      (case x
        ((#\alarm)     (write-string "#\\alarm" port))
        ((#\backspace) (write-string "#\\backspace" port))
        ((#\delete)    (write-string "#\\delete" port))
        ((#\escape)    (write-string "#\\escape" port))
        ((#\newline)   (write-string "#\\newline" port))
        ((#\null)      (write-string "#\\null" port))
        ((#\return)    (write-string "#\\return" port))
        ((#\space)     (write-string "#\\space" port))
        ((#\tab)       (write-string "#\\tab" port))
        ((#\a #\b #\c #\d #\e #\f #\g #\h #\i #\j #\k #\l #\m
          #\n #\o #\p #\q #\r #\s #\t #\u #\v #\w #\x #\y #\z
          #\A #\B #\C #\D #\E #\F #\G #\H #\I #\J #\K #\L #\M
          #\N #\O #\P #\Q #\R #\S #\T #\U #\V #\W #\X #\Y #\Z
          #\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
          #\` #\~ #\! #\@ #\# #\$ #\% #\^ #\& #\* #\( #\) #\- #\_ #\= #\+
          #\[ #\] #\{ #\} #\\ #\| #\; #\: #\' #\" #\< #\> #\, #\. #\/ #\?)
         (write-char #\# port)
         (write-char #\\ port)
         (write-char x port))
        (else
         (write-char #\# port)
         (write-char #\\ port)
         (write-char #\x port)
         (write-string (number->string (char->integer x) 16) port))))
     ((pair? x)
      (write-char #\( port)
      (recur (car x))
      (let lp ((tail (cdr x)))
        (cond
         ((null? tail)
          (write-char #\) port))
         ((pair? tail)
          (write-char #\space port)
          (recur (car tail))
          (lp (cdr tail)))
         (else
          (write-string " . " port)
          (recur tail)
          (write-char #\) port)))))
     ((string? x)
      (cond
       (quote-strings?
        (write-char #\" port)
        (string-for-each (lambda (ch)
                           (case ch
                             ((#\newline)
                              (write-char #\\ port)
                              (write-char #\n port))
                             ((#\\ #\")
                              (write-char #\\ port)
                              (write-char ch port))
                             (else
                              (write-char ch port))))
                         x)
        (write-char #\" port))
       (else
        (write-string x port))))
     ((symbol? x)
      (%write-datum port (symbol->string x) #f))
     ((vector? x)
      (write-char #\# port)
      (recur (vector->list x)))
     ((bytevector? x)
      (write-string "#vu8(" port)
      (let lp ((i 0))
        (when (< i (bytevector-length x))
          (unless (zero? i)
            (write-char #\space port))
          (write-string (number->string (bytevector-u8-ref x i)) port)
          (lp (1+ i))))
      (write-char #\) port))
     ((bitvector? x)
      (write-string "#*" port)
      (let lp ((i 0))
        (when (< i (bitvector-length x))
          (write-char (if (bitvector-ref x i) #\1 #\0) port)
          (lp (1+ i)))))
     ((procedure? x)
      (write-string "#<procedure>" port))
     ((keyword? x)
      (write-string "#:" port)
      (write-string (symbol->string (keyword->symbol x)) port))
     ((record? x)
      (write-record x port write))
     (else
      (recur "unhandled object :("))))

  (define* (display datum #:optional (port (current-output-port)))
    (%write-datum port datum #f))
  (define* (write datum #:optional (port (current-output-port)))
    (%write-datum port datum #t))

  (define* (write-shared datum #:optional (port (current-output-port)))
    (raise (make-unimplemented-error 'write-shared)))
  (define* (write-simple datum #:optional (port (current-output-port)))
    (write datum port))
  )