prepare Unicode normalization for Unicode 16.0.0

Author: duerst

lib/unicode_normalize/normalize.rb

@@ -114,6 +114,7 @@ def self.nfc_one(string)
         last_class = accent_class
       end
     end
+    accents = nfc_one(accents) if accents.length>1 # TODO: change from recursion to loop
     hangul_comp_one(start+accents)
   end
 

template/unicode_norm_gen.tmpl

@@ -112,6 +112,17 @@ accent_array = combining_class.keys + composition_table.keys.collect {|key| key.
 
 composition_starters = composition_table.keys.collect {|key| key.first}
 
+# Special treatment for Unicode 16.0.0
+# Add characters that can be decomposed (even indirectly) so that
+# the first character in the decomposition is a an accent to accents.
+# We do this here up to two levels deep.
+# In the future, there may be even deeper levels.
+starter_accents = composition_starters & accent_array
+decomposition_table.each do |k, v|
+  accent_array << k if starter_accents.include? v.first
+  accent_array << k if starter_accents.include? decomposition_table[v.first]&.first
+end
+
 hangul_no_trailing = []
 0xAC00.step(0xD7A3, 28) {|c| hangul_no_trailing << c}