bug#21448: 25.0.50; `unicode-property-table-internal' in Elisp manual

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 10 Sep 2015 08:27:46 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 21448@debbugs.gnu.org
> 
> I think that all that is missing wrt explaining the example is to
> say (in this node) what `uniprop-table' is here, and why and how
> it is used.

Is the text below OK?

     Here's an example of defining a new category for characters that
     have strong right-to-left directionality (*note Bidirectional
     Display::) and using it in a special category table.  To obtain
     the information about the directionality of characters, the
     example code uses the `bidi-class' Unicode property (*note
     bidi-class: Character Properties.).

          (defvar special-category-table-for-bidi
            ;;     Make an empty category-table.
            (let ((category-table (make-category-table))
                  ;; Create a char-table which gives the 'bidi-class' Unicode
                  ;; property for each character.
                  (uniprop-table (unicode-property-table-internal 'bidi-class)))
              (define-category ?R "Characters of bidi-class R, AL, or RLO"
                               category-table)
              ;; Modify the category entry of each character whose 'bidi-class'
              ;; Unicode property is R, AL, or RLO -- these have a
              ;; right-to-left directionality.
              (map-char-table
               #'(lambda (key val)
                   (if (memq val '(R AL RLO))
                       (modify-category-entry key ?R category-table)))
               uniprop-table)
              category-table))