1 files changed, 77 insertions, 30 deletions

diff --git a/lisp/ielm.el b/lisp/ielm.el
index aa60d5de6c3..944e2453cb9 100644
--- a/lisp/ielm.el
+++ b/lisp/ielm.el
@@ -1,6 +1,6 @@
 ;;; ielm.el --- interaction mode for Emacs Lisp
 
-;; Copyright (C) 1994, 2002, 2003 Free Software Foundation, Inc.
+;; Copyright (C) 1994, 2002, 2003, 2004 Free Software Foundation, Inc.
 
 ;; Author: David Smith <maa036@lancaster.ac.uk>
 ;; Maintainer: FSF
@@ -49,12 +49,57 @@
   :type 'boolean
   :group 'ielm)
 
+(defcustom ielm-prompt-read-only t
+  "If non-nil, the IELM prompt is read only.
+The read only region includes the newline before the prompt.
+Setting this variable does not affect existing IELM runs.
+This works by setting the buffer-local value of `comint-prompt-read-only'.
+Setting that value directly affects new prompts in the current buffer.
+
+If this option is enabled, then the safe way to temporarily
+override the read-only-ness of ielm prompts is to call
+`comint-kill-whole-line' or `comint-kill-region' with no
+narrowing in effect.  This way you will be certain that none of
+the remaining prompts will be accidentally messed up.  You may
+wish to put something like the following in your `.emacs' file:
+
+\(add-hook 'ielm-mode-hook
+          '(lambda ()
+             (define-key ielm-map \"\C-w\" 'comint-kill-region)
+             (define-key ielm-map [C-S-backspace]
+               'comint-kill-whole-line)))
+
+If you set `comint-prompt-read-only' to t, you might wish to use
+`comint-mode-hook' and `comint-mode-map' instead of
+`ielm-mode-hook' and `ielm-map'.  That will affect all comint
+buffers, including ielm buffers.  If you sometimes use ielm on
+text-only terminals or with `emacs -nw', you might wish to use
+another binding for `comint-kill-whole-line'."
+  :type 'boolean
+  :group 'ielm
+  :version "21.4")
+
 (defcustom ielm-prompt "ELISP> "
-  "Prompt used in IELM."
+  "Prompt used in IELM.
+Setting this variable does not affect existing IELM runs.
+
+Interrupting the IELM process with \\<ielm-map>\\[comint-interrupt-subjob],
+and then restarting it using \\[ielm], makes the then current
+default value affect _new_ prompts.  Unless the new prompt
+differs only in text properties from the old one, IELM will no
+longer recognize the old prompts.  However, executing \\[ielm]
+does not update the prompt of an *ielm* buffer with a running process.
+For IELM buffers that are not called `*ielm*', you can execute
+\\[inferior-emacs-lisp-mode] in that IELM buffer to update the value,
+for new prompts.  This works even if the buffer has a running process."
   :type 'string
-  :group 'ielm
-  :get #'(lambda (symbol) (substring-no-properties (symbol-value symbol)))
-  :set #'(lambda (symbol value) (set symbol (propertize value 'read-only t 'rear-nonsticky t))))
+  :group 'ielm)
+
+(defvar ielm-prompt-internal "ELISP> "
+  "Stored value of `ielm-prompt' in the current IELM buffer.
+This is an internal variable used by IELM.  Its purpose is to
+prevent a running IELM process from being messed up when the user
+customizes `ielm-prompt'.")
 
 (defcustom ielm-dynamic-return t
   "*Controls whether \\<ielm-map>\\[ielm-return] has intelligent behaviour in IELM.
@@ -145,9 +190,7 @@ This variable is buffer-local.")
   (define-key ielm-map "\C-c\C-v" 'ielm-print-working-buffer))
 
 (defvar ielm-font-lock-keywords
-  (list
-   (cons (concat "^" (regexp-quote ielm-prompt)) 'font-lock-keyword-face)
-   '("\\(^\\*\\*\\*[^*]+\\*\\*\\*\\)\\(.*$\\)"
+  '(("\\(^\\*\\*\\*[^*]+\\*\\*\\*\\)\\(.*$\\)"
      (1 font-lock-comment-face)
      (2 font-lock-constant-face)))
   "Additional expressions to highlight in ielm buffers.")
@@ -250,8 +293,7 @@ simply inserts a newline."
 (defun ielm-send-input nil
   "Evaluate the Emacs Lisp expression after the prompt."
   (interactive)
-  (let ((buf (current-buffer))
-        ielm-input)                     ; set by ielm-input-sender
+  (let (ielm-input)                     ; set by ielm-input-sender
     (comint-send-input)                 ; update history, markers etc.
     (ielm-eval-input ielm-input)))
 
@@ -374,7 +416,7 @@ simply inserts a newline."
             (setq ** *)
             (setq * ielm-result))
           (setq ielm-output (concat ielm-output "\n"))))
-    (setq ielm-output (concat ielm-output ielm-prompt))
+    (setq ielm-output (concat ielm-output ielm-prompt-internal))
     (comint-output-filter (ielm-process) ielm-output)))
 
 ;;; Process and marker utilities
@@ -414,8 +456,8 @@ The current working buffer may be changed (with a call to
 `set-buffer', or with \\[ielm-change-working-buffer]), and its value
 is preserved between successive evaluations.  In this way, expressions
 may be evaluated in a different buffer than the *ielm* buffer.
-Display the name of the working buffer with \\[ielm-print-working-buffer],
-or the buffer itself with \\[ielm-display-working-buffer].
+By default, its name is shown on the mode line; you can always display
+it with \\[ielm-print-working-buffer], or the buffer itself with \\[ielm-display-working-buffer].
 
 During evaluations, the values of the variables `*', `**', and `***'
 are the results of the previous, second previous and third previous
@@ -426,14 +468,16 @@ buffer, then the values in the working buffer are used.  The variables
 Expressions evaluated by IELM are not subject to `debug-on-quit' or
 `debug-on-error'.
 
-The behaviour of IELM may be customised with the following variables:
-* To stop beeping on error, set `ielm-noisy' to nil
+The behaviour of IELM may be customized with the following variables:
+* To stop beeping on error, set `ielm-noisy' to nil.
 * If you don't like the prompt, you can change it by setting `ielm-prompt'.
-* Set `ielm-dynamic-return' to nil for bindings like `lisp-interaction-mode'
+* If you do not like that the prompt is (by default) read-only, set
+  `ielm-prompt-read-only' to nil.
+* Set `ielm-dynamic-return' to nil for bindings like `lisp-interaction-mode'.
 * Entry to this mode runs `comint-mode-hook' and `ielm-mode-hook'
  (in that order).
 
-Customised bindings may be defined in `ielm-map', which currently contains:
+Customized bindings may be defined in `ielm-map', which currently contains:
 \\{ielm-map}"
   (interactive)
   (comint-mode)
@@ -443,15 +487,16 @@ Customised bindings may be defined in `ielm-map', which currently contains:
   (setq comint-input-sender 'ielm-input-sender)
   (setq comint-process-echoes nil)
   (make-local-variable 'comint-dynamic-complete-functions)
+  (set (make-local-variable 'ielm-prompt-internal) ielm-prompt)
+  (set (make-local-variable 'comint-prompt-read-only) ielm-prompt-read-only)
   (setq comint-dynamic-complete-functions
         '(ielm-tab comint-replace-by-expanded-history ielm-complete-filename ielm-complete-symbol))
   (setq comint-get-old-input 'ielm-get-old-input)
   (make-local-variable 'comint-completion-addsuffix)
-  (setq comint-completion-addsuffix
-        (cons (char-to-string directory-sep-char) ""))
-
+  (setq comint-completion-addsuffix '("/" . ""))
   (setq major-mode 'inferior-emacs-lisp-mode)
   (setq mode-name "IELM")
+  (setq mode-line-process '(":%s on " (:eval (buffer-name ielm-working-buffer))))
   (use-local-map ielm-map)
   (set-syntax-table emacs-lisp-mode-syntax-table)
 
@@ -494,10 +539,11 @@ Customised bindings may be defined in `ielm-map', which currently contains:
     (insert ielm-header)
     (ielm-set-pm (point-max))
     (unless comint-use-prompt-regexp-instead-of-fields
-      (add-text-properties
-       (point-min) (point-max)
-       '(rear-nonsticky t field output inhibit-line-move-field-capture t)))
-    (comint-output-filter (ielm-process) ielm-prompt)
+      (let ((inhibit-read-only t))
+        (add-text-properties
+         (point-min) (point-max)
+         '(rear-nonsticky t field output inhibit-line-move-field-capture t))))
+    (comint-output-filter (ielm-process) ielm-prompt-internal)
     (set-marker comint-last-input-start (ielm-pm))
     (set-process-filter (get-buffer-process (current-buffer)) 'comint-output-filter))
 
@@ -521,12 +567,13 @@ Customised bindings may be defined in `ielm-map', which currently contains:
   "Interactively evaluate Emacs Lisp expressions.
 Switches to the buffer `*ielm*', or creates it if it does not exist."
   (interactive)
-  (if (comint-check-proc "*ielm*")
-      nil
-    (save-excursion
-      (set-buffer (get-buffer-create "*ielm*"))
-      (inferior-emacs-lisp-mode)))
-  (pop-to-buffer "*ielm*"))
+  (let (old-point)
+    (unless (comint-check-proc "*ielm*")
+      (with-current-buffer (get-buffer-create "*ielm*")
+        (unless (zerop (buffer-size)) (setq old-point (point)))
+        (inferior-emacs-lisp-mode)))
+    (pop-to-buffer "*ielm*")
+    (when old-point (push-mark old-point))))
 
 (provide 'ielm)