* lisp/mail/footnote.el: Misc changes in preparation for more

(footnote-section-tag-regexp): Don't require the trailing space.
(Footnote--point-in-body-p, Footnote--get-area-point-min)
(Footnote--get-area-point-max): New functions.
(Footnote-narrow-to-footnotes, Footnote-text-under-cursor): Use them.

1 files changed, 106 insertions, 36 deletions

diff --git a/lisp/mail/footnote.el b/lisp/mail/footnote.el
index 0c39f62f3ee..272672904bf 100644
--- a/lisp/mail/footnote.el
+++ b/lisp/mail/footnote.el
@@ -3,6 +3,7 @@
 ;; Copyright (C) 1997, 2000-2017 Free Software Foundation, Inc.
 
 ;; Author: Steven L Baur <steve@xemacs.org>
+;;         Boruch Baum <boruch_baum@gmx.com>
 ;; Keywords: mail, news
 ;; Version: 0.19
 
@@ -29,9 +30,36 @@
 ;; [1] Footnotes look something like this.  Along with some decorative
 ;; stuff.
 
-;; TODO:
-;; Reasonable Undo support.
-;; more language styles.
+;;;; TODO:
+;; + Reasonable Undo support.
+;;   - could use an `apply' entry in the buffer-undo-list to be warned when
+;;     a footnote we inserted is removed via undo.
+;;   - should try to handle the more general problem of deleting/removing
+;;     footnotes via standard editing commands rather than via footnote
+;;     commands.
+;; + more language styles.
+;; + The key sequence 'C-c ! a C-y C-c ! b' should auto-fill the
+;;   footnote in adaptive fill mode. This does not seem to be a bug in
+;;   `adaptive-fill' because it behaves that way on all point movements
+;; + Handle footmode mode elegantly in all modes, even if that means refuses to
+;;   accept the burden. For example, in a programming language mode, footnotes
+;;   should be commented.
+;; + Manually autofilling the a first footnote should not cause it to
+;;   wrap into the footnote section tag
+;;   + Current solution adds a second newline after the section tag, so it is
+;;     clearly a separate paragraph. There may be stylistic objections to this.
+;; + Footnotes with multiple paragraphs should not have their first
+;;   line out-dented.
+;; + Upon leaving footnote area, perform an auto-fill on an entire
+;;   footnote (including multiple paragraphs), or on entire footnote area.
+;;   + fill-paragraph takes arg REGION, but seemingly only when called
+;;     interactively.
+;; + At some point, it became necessary to change `footnote-section-tag-regexp'
+;;   to remove its trailing space. (Adaptive fill side-effect?)
+;; + useful for lazy testing
+;;   (setq footnote-narrow-to-footnotes-when-editing t)
+;;   (setq footnote-section-tag "Footnotes: ")
+;;   (setq footnote-section-tag-regexp "Footnotes\\(\\[.\\]\\)?:")
 
 ;;; Code:
 
@@ -101,11 +129,15 @@ footnotes."
   :type 'string
   :group 'footnote)
 
-(defcustom footnote-section-tag-regexp "Footnotes\\(\\[.\\]\\)?: "
+(defcustom footnote-section-tag-regexp
+  ;; Even if `footnote-section-tag' has a trailing space, let's not require it
+  ;; here, since it might be trimmed by various commands.
+  "Footnotes\\(\\[.\\]\\)?:"
   "Regexp which indicates the start of a footnote section.
 This variable is disregarded when `footnote-section-tag' is the
 empty string.  Customizing this variable has no effect on buffers
 already displaying footnotes."
+  :version "27.1"
   :type 'regexp
   :group 'footnote)
 
@@ -532,20 +564,15 @@ styles."
 		footnote-end-tag)
 	'footnote-number to)))))
 
-;; Not needed?
+;; Not needed? <-- 2017-12 Boruch: Not my comment! BUT, when I
+;; starting hacking the code, this function
+;; `Footnote-narrow-to-footnotes' was never narrowing, and the result
+;; wasn't breaking anything.
 (defun Footnote-narrow-to-footnotes ()
   "Restrict text in buffer to show only text of footnotes."
-  (interactive)	; testing
-  (goto-char (point-max))
-  (when (re-search-backward footnote-signature-separator nil t)
-    (let ((end (point)))
-      (cond
-       ((and (not (string-equal footnote-section-tag ""))
-	     (re-search-backward
-	      (concat "^" footnote-section-tag-regexp) nil t))
-	(narrow-to-region (point) end))
-       (footnote-text-marker-alist
-	(narrow-to-region (cdar footnote-text-marker-alist) end))))))
+  (interactive) ; testing
+  (narrow-to-region (Footnote--get-area-point-min)
+                    (Footnote--get-area-point-max)))
 
 (defun Footnote-goto-char-point-max ()
   "Move to end of buffer or prior to start of .signature."
@@ -625,28 +652,22 @@ styles."
 	       (< (car e1) (car e2)))))
 
 (defun Footnote-text-under-cursor ()
-  "Return the number of footnote if in footnote text.
+  "Return the number of the current footnote if in footnote text.
 Return nil if the cursor is not positioned over the text of
 a footnote."
-  (when (and (let ((old-point (point)))
-	       (save-excursion
-		 (save-restriction
-		   (Footnote-narrow-to-footnotes)
-		   (and (>= old-point (point-min))
-			(<= old-point (point-max))))))
-	     footnote-text-marker-alist
-             (>= (point) (cdar footnote-text-marker-alist)))
-    (let ((i 1)
-	  alist-txt rc)
+  (when (and footnote-text-marker-alist
+             (<= (Footnote--get-area-point-min)
+                 (point)
+                 (Footnote--get-area-point-max)))
+    (let ((i 1) alist-txt result)
       (while (and (setq alist-txt (nth i footnote-text-marker-alist))
-		  (null rc))
-	(when (< (point) (cdr alist-txt))
-	  (setq rc (car (nth (1- i) footnote-text-marker-alist))))
-	(setq i (1+ i)))
-      (when (and (null rc)
-		 (null alist-txt))
-	(setq rc (car (nth (1- i) footnote-text-marker-alist))))
-      rc)))
+                  (null result))
+        (when (< (point) (cdr alist-txt))
+          (setq result (car (nth (1- i) footnote-text-marker-alist))))
+        (setq i (1+ i)))
+      (when (and (null result) (null alist-txt))
+        (setq result (car (nth (1- i) footnote-text-marker-alist))))
+      result)))
 
 (defun Footnote-under-cursor ()
   "Return the number of the footnote underneath the cursor.
@@ -654,6 +675,53 @@ Return nil if the cursor is not over a footnote."
   (or (get-text-property (point) 'footnote-number)
       (Footnote-text-under-cursor)))
 
+(defun Footnote--point-in-body-p ()
+  "Return non-nil if point is in the buffer text area,
+i.e. before the beginning of the footnote area."
+  (< (point) (Footnote--get-area-point-min)))
+
+(defun Footnote--get-area-point-min (&optional before-tag)
+  "Return start of the first footnote.
+If there is no footnote area, returns `point-max'.
+With optional arg BEFORE-TAG, return position of the `footnote-section-tag'
+instead, if applicable."
+  (cond
+   ;; FIXME: Shouldn't we use `Footnote--get-area-point-max' instead?
+   ((not footnote-text-marker-alist) (point-max))
+   ((not before-tag) (cdr (first footnote-text-marker-alist)))
+   ((string-equal footnote-section-tag "")
+    (cdr (first footnote-text-marker-alist)))
+   (t
+    (save-excursion
+      (goto-char (cdr (first footnote-text-marker-alist)))
+      (if (re-search-backward (concat "^" footnote-section-tag-regexp) nil t)
+          (match-beginning 0)
+        (message "Footnote section tag not found!")
+        ;; This `else' should never happen, and indicates an error,
+        ;; ie. footnotes already exist and a footnote-section-tag is defined,
+        ;; but the section tag hasn't been found. We choose to assume that the
+        ;; user deleted it intentionally and wants us to behave in this buffer
+        ;; as if the section tag was set "", so we do that, now.
+        ;;(setq footnote-section-tag "")
+        ;;
+        ;; HOWEVER: The rest of footnote mode does not currently honor or
+        ;; account for this.
+        ;;
+        ;; To illustrate the difference in behavior, create a few footnotes,
+        ;; delete the section tag, and create another footnote. Then undo,
+        ;; comment the above line (that sets the tag to ""), re-evaluate this
+        ;; function, and repeat.
+        ;;
+        ;; TODO: integrate sanity checks at reasonable operational points.
+        (cdr (first footnote-text-marker-alist)))))))
+
+(defun Footnote--get-area-point-max ()
+  "Return the end of footnote area.
+This is either `point-max' or the start of a `.signature' string, as
+defined by variable `footnote-signature-separator'. If there is no
+footnote area, returns `point-max'."
+  (save-excursion (Footnote-goto-char-point-max)))
+
 ;;; User functions
 
 (defun Footnote-make-hole ()
@@ -739,7 +807,7 @@ delete the footnote with that number."
 	 (point)
 	 (if footnote-spaced-footnotes
 	     (search-forward "\n\n" nil t)
-	   (save-restriction
+           (save-restriction ; <= 2017-12 Boruch: WHY?? I see no narrowing / widening here.
 	     (end-of-line)
 	     (next-single-char-property-change
 	      (point) 'footnote-number nil (Footnote-goto-char-point-max))))))
@@ -855,6 +923,8 @@ play around with the following keys:
     (make-local-variable 'footnote-start-tag)
     (make-local-variable 'footnote-end-tag)
 
+    ;; filladapt is an XEmacs package which AFAIK has never been ported
+    ;; to Emacs.
     (when (boundp 'filladapt-token-table)
       ;; add tokens to filladapt to match footnotes
       ;; 1] xxxxxxxxxxx x x x or [1] x x x x x x x