Groups support

[guile-click.git] / click / help.scm

diff --git a/click/help.scm b/click/help.scm
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+;;; Click --- Command Line Interface Creation Kit for GNU Guile
+;;; Copyright © 2021 Javier Sancho <jsf@jsancho.org>
+;;;
+;;; This file is part of Click.
+;;;
+;;; Click is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; Click is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Click.  If not, see <http://www.gnu.org/licenses/>.
+
+
+(define-module (click help)
+  #:use-module (ice-9 format)
+  #:use-module (click util)
+  #:export (display-error
+            display-help))
+
+
+(define (get-type-description option)
+  "Return allowed type for the value in the option"
+  (assoc-ref (option-type option) 'description))
+
+
+(define (get-title target)
+  "Return the title for the help message"
+  (cond ((procedure? target)
+         (procedure-documentation target))
+        (else
+         target)))
+
+
+(define* (display-help program-name target option-spec #:optional (commands '()))
+  (format #t "Usage: ~a [OPTIONS]
+
+  ~a
+
+Options:
+" program-name (get-title target))
+
+  (let* ((options (map (lambda (option)
+                         (cons (format #f
+                                       "--~a~a~a"
+                                       (car option)
+                                       (let ((single-char
+                                              (option-property option 'single-char)))
+                                         (if single-char
+                                             (format #f ", -~a" single-char)
+                                             ""))
+                                       (let ((value
+                                              (not (option-property option 'flag))))
+                                         (if value
+                                             (format #f " ~a" (get-type-description option))
+                                             "")))
+                               (option-property option 'help "")))
+                       option-spec))
+         (sep (+ 2 (apply max (map (lambda (option)
+                                     (string-length (car option)))
+                                   options)))))
+    (for-each (lambda (option)
+                (format #t
+                        "  ~a~v_~a~%"
+                        (car option)
+                        (- sep (string-length (car option)))
+                        (cdr option)))
+              options)))
+
+
+(define (display-error wrong-option)
+  (format #t "Usage: ~a [OPTIONS]
+Try '~a --help' for help.
+
+Error: No such option: ~a
+" (program-name) (program-name) wrong-option))