UCData 2.1 released with Bidi algorithm

From: Mark Leisher (mleisher@crl.nmsu.edu)
Date: Thu Oct 07 1999 - 17:33:19 EDT

Well, the amount of email requesting info on bidi algorithms finally hit
critical mass and I spent some time today whipping out a simplified version of
the one I developed for our system. I packed it in with the UCData


Version 2.1 of the UCData freeware package has been released. This release
provides some bug fixes, and update for the new (apparently undocumented?)
Unicode 3.0 bidirectional categories, and the addition of the "Pretty Good
Bidi Algorithm."

The PGBA is an elegant and simple one-pass bidi reordering algorithm that
works pretty dang good for most text. It has some deliberate, but (hopefully)
minor shortcomings just so developers who use it have something to keep them
occupied :-) The PGBA is in no way related to the Unicode Bidi Algorithm
except by coincidence.

IMPORTANT: The PGBA is dependent on UCData because of the interpretation of
           certain 3.0 bidi categories. To be explicit, the following
           bidi category assumptions are made when building the character type
           data file:

             "AL" is equivalent to the "R" property.

             "BM", "NSM", "LRE", "RLE", "LRO", "RLO", "PDF" are all equivalent
             to the "ON" property.

           If your character type package of preference has these assumptions,
           then using the PGBA will be no problem.

Short and simple info page:


The distribution is available in .tar.gz and .zip form from:




  o Updated for new Unicode 3.0 bidi property tags.

  o Fixed some problems with signedness and comparison in the Java class.

  o Added a bidi reordering algorithm.
Mark Leisher
Computing Research Lab The first virtue is to restrain the tongue;
New Mexico State University he approaches nearest to the gods who knows
Box 30001, Dept. 3CRL how to be silent, even though he is in the
Las Cruces, NM 88003 right. -- Cato the Younger (95-46 B.C.E)

This archive was generated by hypermail 2.1.2 : Tue Jul 10 2001 - 17:20:53 EDT