master 66ceb14: Support prettified display of fractional numbers

[Eli Zaretskii]

branch: master
commit 66ceb148c7d90be71ead193306a4aa2d1f55674c
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Support prettified display of fractional numbers
    
    * lisp/composite.el (composition-function-table): Define an entry
    for U+2044 FRACTION SLASH, for prettier display of fractional
    numbers.
---
 lisp/composite.el | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lisp/composite.el b/lisp/composite.el
index 47d91c5..0a8dcb8 100644
--- a/lisp/composite.el
+++ b/lisp/composite.el
@@ -747,7 +747,18 @@ All non-spacing characters have this function in
      unicode-category-table))
   ;; for dotted-circle
   (aset composition-function-table #x25CC
-       `([,(purecopy ".\\c^") 0 compose-gstring-for-dotted-circle])))
+       `([,(purecopy ".\\c^") 0 compose-gstring-for-dotted-circle]))
+  ;; For prettier display of fractions
+  (set-char-table-range
+   composition-function-table
+   #x2044
+   ;; We use font-shape-gstring so that if the font doesn't support
+   ;; fractional display, the characters are shown separately, not as
+   ;; a composed cluster.
+   (list (vector (purecopy "[1-9][0-9][0-9]\u2044[0-9]+")
+                 3 'font-shape-gstring)
+         (vector (purecopy "[1-9][0-9]\u2044[0-9]+") 2 'font-shape-gstring)
+         (vector (purecopy "[1-9]\u2044[0-9]+") 1 'font-shape-gstring))))
 
 (defun compose-gstring-for-terminal (gstring _direction)
   "Compose glyph-string GSTRING for terminal display.