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2.9 KiB

;;;; l i s t e n e r . s t k -- A listener "widget"
;;;; Copyright © 1993-1999 Erick Gallesio - I3S-CNRS/ESSI <>
;;;; Permission to use, copy, modify, distribute,and license this
;;;; software and its documentation for any purpose is hereby granted,
;;;; provided that existing copyright notices are retained in all
;;;; copies and that this notice is included verbatim in any
;;;; distributions. No written agreement, license, or royalty fee is
;;;; required for any of the authorized uses.
;;;; This software is provided ``AS IS'' without express or implied
;;;; warranty.
;;;; Author: Erick Gallesio []
;;;; Creation date: 11-Sep-1995 10:16
;;;; Last file update: 3-Sep-1999 19:53 (eg)
(select-module Tk)
;;;; Listener
;;;; A new widget which is dedicated to interactive I/O. We have 4 new options:
;;;; :prompt (">")
;;;; :prompt-color ("red")
;;;; :output-color ("blue")
;;;; :command (a lambda which does nothing)
;;;; The command is executed when a Return is typed in and a complete Sexpr
;;;; has been entered between the last prompt and the return.
(define (listener name . args)
(let* ((prompt-color (get-keyword :prompt-color args "red"))
(output-color (get-keyword :output-color args "blue"))
(prompt (get-keyword :prompt args "> "))
(command (get-keyword :command args (lambda (x) x))))
(define (insert-prompt w)
(w 'insert "end" prompt "list-prompt" " ")
;; Add a mark to the current position
(w 'mark 'set "start_expr" "end-1c")
(w 'mark 'gravity "start_expr" "left")
(w 'see "end"))
(define (enter-expression w action) ;; Called when user type <Return>
(let ((txt (w 'get "start_expr" "insert"))
(exp '()))
(if (or (catch (set! exp (read-from-string txt))) (eof-object? exp))
;; Current expression is not complete
;; We have found an expression which seems complete.
(let ((user-result (apply action (list txt))))
(w 'insert "insert" "\n" "" user-result "list-output" "\n" "")
(insert-prompt w)
(unless (= (modulo (length args) 2) 0)
(error "listener: argument list size is not even ~S" args))
;; Build a list of valid Tk arguments
(let ((tk-args '()))
(do ((args args (cddr args)))
((null? args))
(unless (member (car args) '(:prompt-color :output-color :prompt :command))
(set! tk-args (append tk-args (list (car args) (cadr args))))))
;; Create a text Tk-command with given arguments
(let ((w (apply Tk:text name tk-args)))
(bind w "<Return>" (lambda () (enter-expression w command)))
(w 'tag 'configure "list-prompt" :foreground prompt-color)
(w 'tag 'configure "list-output" :foreground output-color)
(insert-prompt w)
(define (listener-insert-string w str)
(w 'insert "start_expr linestart" str "list-output")
(w 'see "insert"))
(provide "listener")