Re: Small improvements to ruby-mode

[Dmitry Gutov]

On 11.07.2013 15:23, Bozhidar Batsov wrote:
> Still, we should consider functions with names like Float. Currently
> they are not highlighted correctly - Something(test) is highlighted as a
> constant, when obviously it's not.

Fixed, among other things, see the patch at the bottom. We don't 
highlight method calls, so I just disabled highlighting in this case.

> I guess classes, constants and
> functions like this could be font-locked after the first character
> that's not part of the identifier name appears, to avoid the changing of
> the face after the initial character.

Function calls can be identified by having a paren after the name (no 
luck with parenless calls).

But there's really nothing that would distinguish a Math::E reference 
from Foo::C. Or from GC, IO, DL, IRB, URI, XML, HTML, etc.

=== modified file 'lisp/progmodes/ruby-mode.el'
--- lisp/progmodes/ruby-mode.el 2013-07-09 01:17:48 +0000
+++ lisp/progmodes/ruby-mode.el 2013-07-12 20:07:57 +0000
@@ -1351,7 +1351,7 @@
     (progn
       (eval-and-compile
         (defconst ruby-percent-literal-beg-re
-          "\\(%\\)[qQrswWx]?\\([[:punct:]]\\)"
+          "\\(%\\)[qQrswWxIi]?\\([[:punct:]]\\)"
           "Regexp to match the beginning of percent literal.")

         (defconst ruby-syntax-methods-before-regexp
@@ -1387,7 +1387,7 @@
           (funcall
            (syntax-propertize-rules
             ;; $' $" $` .... are variables.
-            ;; ?' ?" ?` are ascii codes.
+            ;; ?' ?" ?` are character literals (one-char strings in 1.9+).
             ("\\([?$]\\)[#\"'`]"
              (1 (unless (save-excursion
                           ;; Not within a string.
@@ -1518,7 +1518,7 @@
             (save-match-data
               (save-excursion
                 (goto-char (nth 8 parse-state))
-                (looking-at "%\\(?:[QWrx]\\|\\W\\)")))))))
+                (looking-at "%\\(?:[QWrxI]\\|\\W\\)")))))))

       (defun ruby-syntax-propertize-expansions (start end)
         (save-excursion
@@ -1848,8 +1848,11 @@
    '("\\(\\$\\|@\\|@@\\)\\(\\w\\|_\\)+"
      0 font-lock-variable-name-face)
    ;; constants
-   '("\\(?:\\_<\\|::\\)\\([A-Z]+\\(\\w\\|_\\)*\\)"
-     1 font-lock-type-face)
+ 
'("\\(?:\\_<\\|::\\)\\([A-Z]+\\(\\w\\|_\\)*\\)\\(?:\\_>[^\(]\\|::\\|\\'\\)"
+     1 (progn
+         (when (eq ?: (char-before))
+           (forward-char -2))
+         font-lock-type-face))
    '("\\(^\\s *\\|[\[\{\(,]\\s *\\|\\sw\\s 
+\\)\\(\\(\\sw\\|_\\)+\\):[^:]" 2 font-lock-constant-face)
    ;; expression expansion
    '(ruby-match-expression-expansion
@@ -1857,6 +1860,9 @@
    ;; negation char
    '("[^[:alnum:]_]\\(!\\)[^=]"
      1 font-lock-negation-char-face)
+   ;; character literals
+   ;; FIXME: Support longer escape sequences.
+   '("\\?\\\\?\\S " 0 font-lock-string-face)
    )
   "Additional expressions to highlight in Ruby mode.")