80 lines
3.0 KiB
Scheme
80 lines
3.0 KiB
Scheme
;;; Gash -- Guile As SHell
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;;; Copyright © 2018, 2019 Timothy Sample <samplet@ngyro.com>
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;;; Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; This file is part of Gash.
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;;;
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;;; Gash is free software: you can redistribute it and/or modify
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;;; it under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation, either version 3 of the License, or
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;;; (at your option) any later version.
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;;;
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;;; Gash is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with Gash. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gash built-ins echo)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26))
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;;; Commentary:
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;;;
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;;; The 'echo' utility.
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;;;
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;;; Code:
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(define (escape->control string)
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(list->string
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(let loop ((lst (string->list string)))
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(if (null? lst) '()
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(let ((char (car lst)))
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(if (or (not (eq? char #\\))
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(null? (cdr lst))) (cons char (loop (cdr lst)))
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(let* ((lst (cdr lst))
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(char (car lst)))
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(case char
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((#\\) (cons #\\ (loop (cdr lst))))
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((#\a) (cons #\alarm (loop (cdr lst))))
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((#\b) (cons #\backspace (loop (cdr lst))))
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((#\c) '())
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;; Guile 2.0.9 does not understand '#\escape',
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;; so we use the older '#\esc'.
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((#\e) (cons #\esc (loop (cdr lst))))
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((#\f) (cons #\page (loop (cdr lst))))
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((#\n) (cons #\newline (loop (cdr lst))))
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((#\r) (cons #\return (loop (cdr lst))))
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((#\t) (cons #\tab (loop (cdr lst))))
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((#\v) (cons #\vtab (loop (cdr lst))))
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((#\0) (error "echo: TODO: \\0NNN"))
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((#\x) (error "echo: TODO: \\xNNN"))))))))))
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(define (option? str)
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(and (> (string-length str) 1)
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(char=? (string-ref str 0) #\-)
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(string-every (cut member <> '(#\E #\e #\n)) (substring str 1))))
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(define (main . args)
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(let* ((options (append-map (compose cdr string->list)
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(take-while option? args)))
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(args (drop-while option? args))
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(newline? (not (member #\n options)))
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(escapes? (fold (lambda (x acc)
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(match x
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(#\e #t)
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(#\E #f)
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(_ acc)))
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#f
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options))
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(string (string-join args)))
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(display (if escapes?
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(escape->control string)
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string))
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(when newline?
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(newline))
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0))
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