module/ice-9/history.scm

   1 ;;;;    Copyright (C) 2000, 2001, 2004, 2006, 2010 Free Software Foundation, Inc.
   2 ;;;;
   3 ;;;; This library is free software; you can redistribute it and/or
   4 ;;;; modify it under the terms of the GNU Lesser General Public
   5 ;;;; License as published by the Free Software Foundation; either
   6 ;;;; version 3 of the License, or (at your option) any later version.
   7 ;;;;
   8 ;;;; This library is distributed in the hope that it will be useful,
   9 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 ;;;; Lesser General Public License for more details.
  12 ;;;;
  13 ;;;; You should have received a copy of the GNU Lesser General Public
  14 ;;;; License along with this library; if not, write to the Free Software
  15 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16 ;;;;
  17 \f
  18 ;;;; A simple value history support
  19
  20 (define-module (ice-9 history)
  21   #:export (value-history-enabled? enable-value-history! disable-value-history!
  22             clear-value-history!))
  23
  24 (define-module* '(value-history))
  25
  26 (define *value-history-enabled?* #f)
  27 (define (value-history-enabled?)
  28   *value-history-enabled?*)
  29
  30 (define (use-value-history x)
  31   (module-use! (current-module)
  32                (resolve-interface '(value-history))))
  33
  34 (define save-value-history
  35   (let ((count 0)
  36         (history (resolve-module '(value-history))))
  37     (lambda (v)
  38       (if (not (unspecified? v))
  39           (let* ((c (1+ count))
  40                  (s (string->symbol (simple-format #f "$~A" c))))
  41             (simple-format #t "~A = " s)
  42             (module-define! history s v)
  43             (module-export! history (list s))
  44             (set! count c))))))
  45
  46 (define (enable-value-history!)
  47   (if (not (value-history-enabled?))
  48       (begin
  49         (add-hook! before-eval-hook use-value-history)
  50         (add-hook! before-print-hook save-value-history)
  51         (set! *value-history-enabled?* #t))))
  52
  53 (define (disable-value-history!)
  54   (if (value-history-enabled?)
  55       (begin
  56         (remove-hook! before-eval-hook use-value-history)
  57         (remove-hook! before-print-hook save-value-history)
  58         (set! *value-history-enabled?* #f))))
  59
  60 (define (clear-value-history!)
  61   (let ((history (resolve-module '(value-history))))
  62     (hash-clear! (module-obarray history))
  63     (hash-clear! (module-obarray (module-public-interface history)))))
  64
  65 (enable-value-history!)