Treat ' like ’ even when not matching `

This is simpler and easier to explain, and should encourage better
typography.  Do this in Electric Quote mode and when translating
quotes in docstrings.  Inspired by a suggestion by Dmitry Gutov	in:
https://lists.gnu.org/archive/html/emacs-devel/2015-08/msg00806.html
* doc/emacs/text.texi (Quotation Marks):
* doc/lispref/help.texi (Keys in Documentation):
* etc/NEWS:
Document this.
* lisp/electric.el (electric-quote-post-self-insert-function):
* src/doc.c (Fsubstitute_command_keys):
Always treat ' like ’ even when not matched by an open quote.

1 files changed, 14 insertions, 19 deletions

diff --git a/lisp/electric.el b/lisp/electric.el
index 8ca09316bcb..bef5bb9fec7 100644
--- a/lisp/electric.el
+++ b/lisp/electric.el
@@ -453,7 +453,7 @@ This requotes when a quoting key is typed."
         (save-excursion
           (if (eq last-command-event ?\`)
               (cond ((and (electric--insertable-p "“")
-                          (re-search-backward "[`‘]`" (- (point) 2) t))
+                          (search-backward "‘`" (- (point) 2) t))
                      (replace-match "“")
                      (when (and electric-pair-mode
                                 (eq (cdr-safe
@@ -465,19 +465,14 @@ This requotes when a quoting key is typed."
                           (search-backward "`" (1- (point)) t))
                      (replace-match "‘")
                      (setq last-command-event ?‘)))
-            (let ((pos (point)))
-              (if (memq (char-before (1- (point))) '(?\' ?’))
-                  (when (and (search-backward "“" start t)
-                             (eq pos (re-search-forward
-                                      "“\\(\\([^‘”]\\|‘[^‘’”]*’\\)*\\)['’]'"
-                                      pos t)))
-                    (replace-match "“\\1”")
-                    (setq last-command-event ?”))
-                (when (and (search-backward "‘" start t)
-                           (eq pos (re-search-forward
-                                    "‘\\([^’]*\\)'" pos t)))
-                  (replace-match "‘\\1’")
-                  (setq last-command-event ?’))))))))))
+            (cond ((and (electric--insertable-p "”")
+                        (search-backward "’'" (- (point) 2) t))
+                   (replace-match "”")
+                   (setq last-command-event ?”))
+                  ((and (electric--insertable-p "’")
+                        (search-backward "'" (1- (point)) t))
+                   (replace-match "’")
+                   (setq last-command-event ?’)))))))))
 
 (put 'electric-quote-post-self-insert-function 'priority 10)
 
@@ -488,11 +483,11 @@ With a prefix argument ARG, enable Electric Quote mode if
 ARG is positive, and disable it otherwise.  If called from Lisp,
 enable the mode if ARG is omitted or nil.
 
-When enabled, this replaces \\=`foo bar' with \\=‘foo bar\\=’ and replaces
-\\=`\\=`foo bar'' with “foo bar” as you type.  This occurs only in
-comments, strings, and text paragraphs, and these are selectively
-controlled with ‘electric-quote-comment’,
-‘electric-quote-string’, and ‘electric-quote-paragraph’.
+When enabled, as you type this replaces \\=` with \\=‘, \\=' with \\=’,
+\\=`\\=` with “, and \\='\\=' with ”.  This occurs only in comments, strings,
+and text paragraphs, and these are selectively controlled with
+‘electric-quote-comment’, ‘electric-quote-string’, and
+‘electric-quote-paragraph’.
 
 This is a global minor mode.  To toggle the mode in a single buffer,
 use ‘electric-quote-local-mode’."