Add ICU4J license infromation.

NOTICE

@@ -2,7 +2,7 @@ twitter-cldr-rb is a Ruby implementation of the Common Locale Data Repository
 Copyright (C) 2012 Twitter, Inc.
 
 
-Portions of this gem were borrowed from Sven Fuchs' ruby-cldr gem.  Here is
+Portions of this gem were borrowed from Sven Fuchs' ruby-cldr gem. Here is
 the license that accompanied Mr. Fuchs' code:
 
 Copyright (c) 2009 Sven Fuchs
@@ -117,4 +117,38 @@ the software.
   6. THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
      IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
      WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-     PURPOSE.
+     PURPOSE.
+
+
+TwitterCldr::Collation::ImplicitCollationElements module was ported from
+the ICU4J library (http://site.icu-project.org). Here is its license:
+
+ICU License - ICU 1.8.1 and later
+
+COPYRIGHT AND PERMISSION NOTICE
+
+Copyright (c) 1995-2012 International Business Machines Corporation and others
+
+All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, and/or sell copies of the Software,
+and to permit persons to whom the Software is furnished to do so, provided that
+the above copyright notice(s) and this permission notice appear in all copies
+of the Software and that both the above copyright notice(s) and this permission
+notice appear in supporting documentation.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL
+THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM,
+OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER
+RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
+OR PERFORMANCE OF THIS SOFTWARE.
+
+Except as contained in this notice, the name of a copyright holder shall not be
+used in advertising or otherwise to promote the sale, use or other dealings in
+this Software without prior written authorization of the copyright holder.

lib/twitter_cldr/collation/collator.rb

@@ -6,14 +6,13 @@
 module TwitterCldr
   module Collation
 
+    # Collator class uses fractional collation elements table form CLDR to generate sort keys for Unicode strings
+    # as well as compare and sort such strings by generated sort keys.
+    #
     class Collator
 
       FRACTIONAL_UCA_SHORT_RESOURCE = 'collation/FractionalUCA_SHORT.txt'
 
-      def sort_key(string_or_code_points)
-        sort_key_for_code_points(get_code_points(string_or_code_points))
-      end
-
       def sort(strings)
         strings.map{ |s| [s, comparison_key(s)] }.sort{ |a, b| compare_keys(a[1], b[1]) }.map(&:first)
       end
@@ -22,6 +21,10 @@ def compare(string_a, string_b)
         string_a == string_b ? 0 : compare_keys(comparison_key(string_a), comparison_key(string_b))
       end
 
+      def sort_key(string_or_code_points)
+        sort_key_for_code_points(get_code_points(string_or_code_points))
+      end
+
       def trie
         @trie ||= self.class.trie
       end

lib/twitter_cldr/collation/implicit_collation_elements.rb

@@ -9,6 +9,8 @@ module Collation
     # Module for generation of implicit collation elements for code points (including some CJK characters), that are
     # not explicitly mentioned in the collation elements table.
     #
+    # This module was ported from the ICU4J library (ImplicitCEGenerator class). See NOTICE file for license information.
+    #
     module ImplicitCollationElements
 
       DEFAULT_SECONDARY_AND_TERTIARY = 5