bug#24710: 26.0.50; Feature request: Replace double quotes in electric-quote-mode

[Philipp Stephani <p.stephani2@gmail.com>]

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Paul Eggert <eggert@cs.ucla.edu> schrieb am Fr., 14. Juli 2017 um 14:49 Uhr:

> > Currently electric-quote-mode only replaces ' and `.  I propose that
> > it also replace " with a left double quote after spaces, newlines, and
> > open parentheses, and with a right double quote after alphanumerics and
> > other punctuation.
>
> This sounds reasonable, though I suppose it should be controlled by an
> option,
> since some people may prefer the current behavior where `` and '' are the
> only
> convenient ways to get curved double quotes.
>
> Also, shouldn't it always replace " with a curved quote of one flavor of
> the
> other? I'm puzzled as to why one would want " to stay straight, when the
> option
> is enabled.
>
>
>
OK, here's a patch.

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From 905cb83dec024e9691ca888b006566c3b3042e72 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Sun, 23 Jul 2017 21:58:49 +0200
Subject: [PATCH] Electric quote mode: Conditionally replace " (Bug#24710)

* lisp/electric.el (electric-quote-replace-double): New user option.
(electric-quote-post-self-insert-function): Use it.

* electric-tests.el (electric-quote-replace-double-disabled)
(electric-quote-replace-double-enabled)
(electric-quote-context-sensitive-bob-replace-double)
(electric-quote-context-sensitive-bol-replace-double)
(electric-quote-context-sensitive-after-space-replace-double)
(electric-quote-context-sensitive-after-letter-replace-double)
(electric-quote-context-sensitive-after-paren-replace-double): New
unit tests.
---
 etc/NEWS                    |  5 ++++
 lisp/electric.el            | 24 ++++++++++++++++---
 test/lisp/electric-tests.el | 56 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 3 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 4cb02bf518..25b9b7eb03 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -157,6 +157,11 @@ line, after a whitespace character, and after an opening parenthesis;
 and it will replace the apostrophe by a closing quote character in all
 other cases.
 
+** The new users option 'electric-quote-replace-double' controls
+whether a double quote is also replaced in 'electric-quote-mode'.  If
+non-nil, a double ASCII quote is replaced by a double typographic
+quote.
+
 ** The new variable 'electric-quote-inhibit-functions' controls when
 to disable electric quoting based on context.  Major modes can add
 functions to this list; Emacs will temporarily disable
diff --git a/lisp/electric.el b/lisp/electric.el
index a71e79ff78..0ad6b284e4 100644
--- a/lisp/electric.el
+++ b/lisp/electric.el
@@ -451,6 +451,16 @@ electric-quote-context-sensitive
   :version "26.1"
   :type 'boolean :safe #'booleanp :group 'electricity)
 
+(defcustom electric-quote-replace-double nil
+  "Non-nil means to replace \" with an electric double quote.
+If `electric-quote-context-sensitive' is nil, Emacs replaces \"
+with a closing double quote.  Otherwise, it replaces \" with an
+opening double quote after a line break, whitespace, opening
+parenthesis, or quote, and with a closing double quote
+otherwise."
+  :version "26.1"
+  :type 'boolean :safe #'booleanp :group 'electricity)
+
 (defvar electric-quote-inhibit-functions ()
   "List of functions that should inhibit electric quoting.
 When the variable `electric-quote-mode' is non-nil, Emacs will
@@ -467,7 +477,9 @@ electric-quote-post-self-insert-function
   (when (and electric-quote-mode
              (or (eq last-command-event ?\')
                  (and (not electric-quote-context-sensitive)
-                      (eq last-command-event ?\`)))
+                      (eq last-command-event ?\`))
+                 (and electric-quote-replace-double
+                      (eq last-command-event ?\")))
              (not (run-hook-with-args-until-success
                    'electric-quote-inhibit-functions))
              (if (derived-mode-p 'text-mode)
@@ -506,13 +518,19 @@ electric-quote-post-self-insert-function
                       (setq last-command-event q<<))
                      ((search-backward (string backtick) (1- (point)) t)
                       (replace-match (string q<))
-                      (setq last-command-event q<)))
+                      (setq last-command-event q<))
+                     ((search-backward "\"" (1- (point)) t)
+                      (replace-match (string q<<))
+                      (setq last-command-event q<<)))
              (cond ((search-backward (string q> ?') (- (point) 2) t)
                     (replace-match (string q>>))
                     (setq last-command-event q>>))
                    ((search-backward "'" (1- (point)) t)
                     (replace-match (string q>))
-                    (setq last-command-event q>))))))))))
+                    (setq last-command-event q>))
+                   ((search-backward "\"" (1- (point)) t)
+                    (replace-match (string q>>))
+                    (setq last-command-event q>>))))))))))
 
 (put 'electric-quote-post-self-insert-function 'priority 10)
 
diff --git a/test/lisp/electric-tests.el b/test/lisp/electric-tests.el
index c6ffccc079..5b4b98b802 100644
--- a/test/lisp/electric-tests.el
+++ b/test/lisp/electric-tests.el
@@ -617,6 +617,19 @@ electric-quote-closing-double
   :fixture-fn #'electric-quote-local-mode
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test electric-quote-replace-double-disabled
+  "" "\"" :expected-string "\"" :expected-point 2
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :test-in-comments nil :test-in-strings nil)
+
+(define-electric-pair-test electric-quote-replace-double-enabled
+  "" "\"" :expected-string "”" :expected-point 2
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (define-electric-pair-test electric-quote-context-sensitive-backtick
   "" "`" :expected-string "`" :expected-point 2
   :modes '(text-mode)
@@ -638,6 +651,14 @@ electric-quote-context-sensitive-bob-double
   :bindings '((electric-quote-context-sensitive . t))
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test electric-quote-context-sensitive-bob-replace-double
+  "" "\"" :expected-string "“" :expected-point 2
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-context-sensitive . t)
+              (electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (define-electric-pair-test electric-quote-context-sensitive-bol-single
   "a\n" "--'" :expected-string "a\n‘" :expected-point 4
   :modes '(text-mode)
@@ -652,6 +673,14 @@ electric-quote-context-sensitive-bol-double
   :bindings '((electric-quote-context-sensitive . t))
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test electric-quote-context-sensitive-bol-replace-double
+  "a\n" "--\"" :expected-string "a\n“" :expected-point 4
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-context-sensitive . t)
+              (electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (define-electric-pair-test electric-quote-context-sensitive-after-space-single
   " " "-'" :expected-string " ‘" :expected-point 3
   :modes '(text-mode)
@@ -666,6 +695,15 @@ electric-quote-context-sensitive-after-space-double
   :bindings '((electric-quote-context-sensitive . t))
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test
+  electric-quote-context-sensitive-after-space-replace-double
+  " " "-\"" :expected-string " “" :expected-point 3
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-context-sensitive . t)
+              (electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (define-electric-pair-test electric-quote-context-sensitive-after-letter-single
   "a" "-'" :expected-string "a’" :expected-point 3
   :modes '(text-mode)
@@ -680,6 +718,15 @@ electric-quote-context-sensitive-after-letter-double
   :bindings '((electric-quote-context-sensitive . t))
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test
+  electric-quote-context-sensitive-after-letter-replace-double
+  "a" "-\"" :expected-string "a”" :expected-point 3
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-context-sensitive . t)
+              (electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 (define-electric-pair-test electric-quote-context-sensitive-after-paren-single
   "(" "-'" :expected-string "(‘" :expected-point 3
   :modes '(text-mode)
@@ -694,6 +741,15 @@ electric-quote-context-sensitive-after-paren-double
   :bindings '((electric-quote-context-sensitive . t))
   :test-in-comments nil :test-in-strings nil)
 
+(define-electric-pair-test
+  electric-quote-context-sensitive-after-paren-replace-double
+  "(" "-\"" :expected-string "(“" :expected-point 3
+  :modes '(text-mode)
+  :fixture-fn #'electric-quote-local-mode
+  :bindings '((electric-quote-context-sensitive . t)
+              (electric-quote-replace-double . t))
+  :test-in-comments nil :test-in-strings nil)
+
 ;; Simulate ‘markdown-mode’: it sets both ‘comment-start’ and
 ;; ‘comment-use-syntax’, but derives from ‘text-mode’.
 (define-electric-pair-test electric-quote-markdown-in-text
-- 
2.13.3