tildify.el: introduce a `tildify-space-string' variable

* textmodes/tildify.el (tildify-space-string): New variable for
specifying representation of a hard space -- a no-break space by
default.  Being a buffer-local variable it is much easier to
handle than `tildify-string-alist' that has been used so far.  It
also works better with derived modes.
(tildify-string-alist): Mark as obsolete.

* textmodes/tex-mode.el (tex-common-initialization): Set
`tildify-space-string' variable in all variants of TeX mode since
`tildify-string-alist' is now empty by default.

* nxml/nxml-mode.el (nxml-mode): Ditto in `nxml-mode'.  If
encoding supports it use no-break space instead of character
entity; this changes previous default which used a numeric
reference.

* textmodes/sgml-mode.el (sgml-mode): ditto in `sgml-mode'.  If
encoding does not support no-break space, use numeric reference;
this changes previous default which used named entity (“ ”)
in HTML mode.

5 files changed, 71 insertions, 13 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 696b384c3f9..33d341f8351 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,26 @@
+2014-11-17  Michal Nazarewicz  <mina86@mina86.com>
+
+        * textmodes/tildify.el (tildify-space-string): New variable for
+        specifying representation of a hard space -- a no-break space by
+        default.  Being a buffer-local variable it is much easier to
+        handle than `tildify-string-alist' that has been used so far.  It
+        also works better with derived modes.
+        (tildify-string-alist): Mark as obsolete.
+
+        * textmodes/tex-mode.el (tex-common-initialization): Set
+        `tildify-space-string' variable in all variants of TeX mode since
+        `tildify-string-alist' is now empty by default.
+
+        * nxml/nxml-mode.el (nxml-mode): Ditto in `nxml-mode'.  If
+        encoding supports it use no-break space instead of character
+        entity; this changes previous default which used a numeric
+        reference.
+
+        * textmodes/sgml-mode.el (sgml-mode): ditto in `sgml-mode'.  If
+        encoding does not support no-break space, use numeric reference;
+        this changes previous default which used named entity (?&nbsp;?)
+        in HTML mode.
+
 2014-11-17  Ulf Jasper  <ulf.jasper@web.de>
 
         Fix bug#5433.
diff --git a/lisp/nxml/nxml-mode.el b/lisp/nxml/nxml-mode.el
index 4859bbc7a77..47f806693df 100644
--- a/lisp/nxml/nxml-mode.el
+++ b/lisp/nxml/nxml-mode.el
@@ -449,6 +449,8 @@ reference.")
     (when rng-validate-mode
       (rng-validate-while-idle (current-buffer)))))
 
+(defvar tildify-space-string)
+
 ;;;###autoload
 (define-derived-mode nxml-mode text-mode "nXML"
   ;; We use C-c C-i instead of \\[nxml-balanced-close-start-tag-inline]
@@ -505,6 +507,14 @@ be treated as a single markup item, set the variable
 Many aspects this mode can be customized using
 \\[customize-group] nxml RET."
   ;; (kill-all-local-variables)
+  ;; If encoding does not allow non-break space character, use reference.
+  ;; FIXME: This duplicates code from sgml-mode, perhaps derive from it?
+  ;; FIXME: Perhaps use &nbsp; if possible (e.g. XHTML)?
+  (setq-local tildify-space-string
+              (if (equal (decode-coding-string
+                          (encode-coding-string " " buffer-file-coding-system)
+                          buffer-file-coding-system) " ")
+                  " " "&#160;"))
   (set (make-local-variable 'mode-line-process) '((nxml-degraded "/degraded")))
   ;; We'll determine the fill prefix ourselves
   (make-local-variable 'adaptive-fill-mode)
diff --git a/lisp/textmodes/sgml-mode.el b/lisp/textmodes/sgml-mode.el
index 39ac0621733..9d1cb0373fa 100644
--- a/lisp/textmodes/sgml-mode.el
+++ b/lisp/textmodes/sgml-mode.el
@@ -456,6 +456,8 @@ This function is designed for use in `fill-nobreak-predicate'.
          (skip-chars-backward "/?!")
          (eq (char-before) ?<))))
 
+(defvar tildify-space-string)
+
 ;;;###autoload
 (define-derived-mode sgml-mode text-mode '(sgml-xml-mode "XML" "SGML")
   "Major mode for editing SGML documents.
@@ -477,6 +479,13 @@ Do \\[describe-key] on the following bindings to discover what they do.
 \\{sgml-mode-map}"
   (make-local-variable 'sgml-saved-validate-command)
   (make-local-variable 'facemenu-end-add-face)
+  ;; If encoding does not allow non-break space character, use reference.
+  ;; FIXME: Perhaps use &nbsp; if possible (e.g. when we know its HTML)?
+  (setq-local tildify-space-string
+              (if (equal (decode-coding-string
+                          (encode-coding-string " " buffer-file-coding-system)
+                          buffer-file-coding-system) " ")
+                  " " "&#160;"))
   ;;(make-local-variable 'facemenu-remove-face-function)
   ;; A start or end tag by itself on a line separates a paragraph.
   ;; This is desirable because SGML discards a newline that appears
diff --git a/lisp/textmodes/tex-mode.el b/lisp/textmodes/tex-mode.el
index bc10eab0498..0cfc0cfe3dc 100644
--- a/lisp/textmodes/tex-mode.el
+++ b/lisp/textmodes/tex-mode.el
@@ -1203,9 +1203,13 @@ Entering SliTeX mode runs the hook `text-mode-hook', then the hook
   (setq tex-command slitex-run-command)
   (setq tex-start-of-header "\\\\documentstyle{slides}\\|\\\\documentclass{slides}"))
 
+(defvar tildify-space-string)
+
 (defun tex-common-initialization ()
   ;; Regexp isearch should accept newline and formfeed as whitespace.
   (setq-local search-whitespace-regexp "[ \t\r\n\f]+")
+  ;; Use tilde as hard-space character in tildify package.
+  (setq-local tildify-space-string "~")
   ;; A line containing just $$ is treated as a paragraph separator.
   (setq-local paragraph-start "[ \t]*$\\|[\f\\\\%]\\|[ \t]*\\$\\$")
   ;; A line starting with $$ starts a paragraph,
diff --git a/lisp/textmodes/tildify.el b/lisp/textmodes/tildify.el
index 91f5a38ce0b..865dcecbecc 100644
--- a/lisp/textmodes/tildify.el
+++ b/lisp/textmodes/tildify.el
@@ -4,7 +4,7 @@
 
 ;; Author:     Milan Zamazal <pdm@zamazal.org>
 ;;             Michal Nazarewicz <mina86@mina86.com>
-;; Version:    4.5.4
+;; Version:    4.5.5
 ;; Keywords:   text, TeX, SGML, wp
 
 ;; This file is part of GNU Emacs.
@@ -86,15 +86,24 @@ mode, the item for the mode SYMBOL is looked up in the alist instead."
                                        (integer :tag "Group "))
                                (symbol :tag "Like other")))))
 
-(defcustom tildify-string-alist
-  '((latex-mode . "~")
-    (tex-mode . latex-mode)
-    (plain-tex-mode . latex-mode)
-    (sgml-mode . "&nbsp;")
-    (html-mode . sgml-mode)
-    (xml-mode . "&#160;") ; XML does not define &nbsp; use numeric reference
-    (nxml-mode . xml-mode)
-    (t . " "))
+(defcustom tildify-space-string "\u00A0"
+  "Representation of a hard (a.k.a. no-break) space in current major mode.
+
+Used by `tildify-buffer' in places where space is required but line
+cannot be broken.  For example \"~\" for TeX or \"&#160;\" for SGML,
+HTML and XML modes.  A no-break space Unicode character (\"\\u00A0\")
+might be used for other modes if compatible encoding is used.
+
+If nil, current major mode has no way to represent a hard space."
+  :version "25.1"
+  :group 'tildify
+  :type '(choice (const :tag "Space character (no hard-space representation)"
+                        " ")
+                 (const :tag "No-break space (U+00A0)" "\u00A0")
+                 (string :tag "Custom string"))
+  :safe t)
+
+(defcustom tildify-string-alist ()
   "Alist specifying what is a hard space in the current major mode.
 
 Each alist item is of the form (MAJOR-MODE . STRING) or
@@ -118,6 +127,8 @@ mode, the item for the mode SYMBOL is looked up in the alist instead."
                        (choice (const  :tag "No-break space (U+00A0)" "\u00A0")
                                (string :tag "String    ")
                                (symbol :tag "Like other")))))
+(make-obsolete-variable 'tildify-string-alist
+                        'tildify-space-string "25.1")
 
 (defcustom tildify-ignored-environments-alist
   `((latex-mode
@@ -193,7 +204,7 @@ END-REGEX defines end of the corresponding text part and can be either:
 ;;;###autoload
 (defun tildify-region (beg end &optional dont-ask)
   "Add hard spaces in the region between BEG and END.
-See variables `tildify-pattern-alist', `tildify-string-alist', and
+See variables `tildify-pattern-alist', `tildify-space-string', and
 `tildify-ignored-environments-alist' for information about configuration
 parameters.
 This function performs no refilling of the changed text.
@@ -214,7 +225,7 @@ won't be prompted for confirmation of each substitution."
 ;;;###autoload
 (defun tildify-buffer (&optional dont-ask)
   "Add hard spaces in the current buffer.
-See variables `tildify-pattern-alist', `tildify-string-alist', and
+See variables `tildify-pattern-alist', `tildify-space-string', and
 `tildify-ignored-environments-alist' for information about configuration
 parameters.
 This function performs no refilling of the changed text.
@@ -303,7 +314,8 @@ replacements done and response is one of symbols: t (all right), nil
     (let* ((alist (tildify--pick-alist-entry tildify-pattern-alist))
            (regexp (car alist))
            (match-number (cadr alist))
-           (tilde (tildify--pick-alist-entry tildify-string-alist))
+           (tilde (or (tildify--pick-alist-entry tildify-string-alist)
+                      tildify-space-string))
            (end-marker (copy-marker end))
            answer
            bad-answer