Enhance ispell-skip-region-alist by generating part of it at runtime.

* lisp/textmodes/ispell.el (ispell--\\w-filter, ispell--make-\\w-expression)
(ispell--make-filename-or-URL-re): New functions which generate a regexp.
(ispell-skip-region-alist): Remove the bit that matches a filename/URL, etc.
(ispell-begin-skip-region-regexp, ispell-skip-region-list, ispell-message):
Include the result of ispell--make-filename-or-URL-re in regexps.

1 files changed, 54 insertions, 5 deletions

diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index 0f1806c888..1b26b4905a 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -1782,6 +1782,51 @@ Extended character mode can be changed for this buffer by placing
 a `~' followed by an extended-character mode -- such as `~.tex'.
 The last occurring definition in the buffer will be used.")
 
+(defun ispell--\\w-filter (char)
+  "Return CHAR in a string when CHAR doesn't have \"word\" syntax,
+nil otherwise.  CHAR must be a character."
+  (let ((str (string char)))
+    (and
+     (not (string-match "\\w" str))
+     str)))
+
+(defun ispell--make-\\w-expression (chars)
+  "Make a regular expression like \"\\(\\w\\|[-_]\\)\".
+This (parenthesized) expression matches either a character of
+\"word\" syntax or one in CHARS.
+
+CHARS is a string of characters.  A member of CHARS is omitted
+from the expression if it already has word syntax.  (Be careful
+about special characters such as ?\\, ?^, ?], and ?- in CHARS.)
+If after this filtering there are no chars left, or only one, a
+special form of the expression is generated."
+  (let ((filtered
+	 (mapconcat #'ispell--\\w-filter chars "")))
+    (concat
+     "\\(\\w"
+     (cond
+      ((equal filtered "")
+       "\\)")
+      ((eq (length filtered) 1)
+       (concat "\\|" filtered "\\)"))
+      (t
+       (concat "\\|[" filtered "]\\)"))))))
+
+(defun ispell--make-filename-or-URL-re ()
+  "Construct a regexp to match some file names or URLs or email addresses.
+The expression is crafted to match as great a variety of these
+objects as practicable, without too many false matches happening."
+  (concat ;"\\(--+\\|_+\\|"
+          "\\(/\\w\\|\\("
+          (ispell--make-\\w-expression "-_")
+          "+[.:@]\\)\\)"
+          (ispell--make-\\w-expression "-_")
+          "*\\([.:/@]+"
+          (ispell--make-\\w-expression "-_~=?&")
+          "+\\)+"
+          ;"\\)"
+          ))
+
 ;;;###autoload
 (defvar ispell-skip-region-alist
   `((ispell-words-keyword	   forward-line)
@@ -1798,7 +1843,7 @@ The last occurring definition in the buffer will be used.")
     ;; Matches e-mail addresses, file names, http addresses, etc.  The
     ;; `-+' `_+' patterns are necessary for performance reasons when
     ;; `-' or `_' part of word syntax.
-    (,(purecopy "\\(--+\\|_+\\|\\(/\\w\\|\\(\\(\\w\\|[-_]\\)+[.:@]\\)\\)\\(\\w\\|[-_]\\)*\\([.:/@]+\\(\\w\\|[-_~=?&]\\)+\\)+\\)"))
+;    (,(purecopy "\\(--+\\|_+\\|\\(/\\w\\|\\(\\(\\w\\|[-_]\\)+[.:@]\\)\\)\\(\\w\\|[-_]\\)*\\([.:/@]+\\(\\w\\|[-_~=?&]\\)+\\)+\\)"))
     ;; above checks /.\w sequences
     ;;("\\(--+\\|\\(/\\|\\(\\(\\w\\|[-_]\\)+[.:@]\\)\\)\\(\\w\\|[-_]\\)*\\([.:/@]+\\(\\w\\|[-_~=?&]\\)+\\)+\\)")
     ;; This is a pretty complex regexp.  It can be simplified to the following:
@@ -3387,7 +3432,8 @@ Must be called after `ispell-buffer-local-parsing' due to dependence on mode."
               (if (string= "" comment-end) "^" (regexp-quote comment-end)))
           (if (and (null ispell-check-comments) comment-start)
               (regexp-quote comment-start))
-          (ispell-begin-skip-region ispell-skip-region-alist)))
+          (ispell-begin-skip-region ispell-skip-region-alist)
+          (ispell--make-filename-or-URL-re)))
    "\\|"))
 
 
@@ -3426,6 +3472,8 @@ Manual checking must include comments and tib references.
 The list is of the form described by variable `ispell-skip-region-alist'.
 Must be called after `ispell-buffer-local-parsing' due to dependence on mode."
   (let ((skip-alist ispell-skip-region-alist))
+    (setq skip-alist (append (list (list (ispell--make-filename-or-URL-re)))
+                             skip-alist))
     ;; only additional explicit region definition is tex.
     (if (eq ispell-parser 'tex)
 	(setq case-fold-search nil
@@ -4119,9 +4167,10 @@ You can bind this to the key C-c i in GNUS or mail by adding to
 		      (ispell-non-empty-string vm-included-text-prefix)))
 	     (t default-prefix)))
 	   (ispell-skip-region-alist
-	    (cons (list (concat "^\\(" cite-regexp "\\)")
-			(function forward-line))
-		  ispell-skip-region-alist))
+	    (cons (list (ispell--make-filename-or-URL-re))
+                  (cons (list (concat "^\\(" cite-regexp "\\)")
+                              (function forward-line))
+                        ispell-skip-region-alist)))
 	   (old-case-fold-search case-fold-search)
 	   (dictionary-alist ispell-message-dictionary-alist)
 	   (ispell-checking-message t))