Issue #12831 has been updated by Mrlaura (QUANG NGUYEN). Thanks to everyone who investigated and fixed this grapheme segmentation issue. One related detail worth highlighting is that correct grapheme segmentation doesn't automatically guarantee Unicode-equivalent string comparisons. For example, "é" (U+00E9) and "e" + U+0301 are both single grapheme clusters, but their underlying code points differ. For text matching or Levenshtein distance over user-perceived characters, it's often useful to normalize both strings to NFC before splitting them into grapheme clusters. It's also important to use a GraphemeBreakTest version matching the Unicode rules implemented by the Ruby version being tested. A related technical discussion is available here: https://www.levenshtein.net/unicode-and-grapheme-safe-levenshtein For transparency, I contribute to that reference. Thanks again for improving Ruby's Unicode support! ---------------------------------------- Feature #12831: /\X/ (extended grapheme cluster) can't pass unicode.org's GraphemeBreakTest https://bugs.ruby-lang.org/issues/12831#change-119477 * Author: mtsmfm (Fumiaki Matsushima) * Status: Closed * Assignee: naruse (Yui NARUSE) ---------------------------------------- I'm trying to replace Rails's grapheme implementation (http://api.rubyonrails.org/classes/ActiveSupport/Multibyte/Unicode.html#meth...) with Ruby's extended grapheme cluster (/X/). https://github.com/rails/rails/issues/26743 I noticed that Ruby's grapheme cluster can't pass unicode.org's GraphemeBreakTest. Following test script will fail on Ruby 2.2/2.3 ~~~ ruby require 'rubygems' require 'open-uri' require 'test/unit' UNICODE_VERSION = if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("2.3.0") "8.0.0" else "7.0.0" end class TestGrapheme < Test::Unit::TestCase # https://github.com/rails/rails/blob/v5.0.0.1/activesupport/test/multibyte_gr... def test_breaks each_line_of_break_tests do |*cols| *clusters, comment = *cols string = clusters.map {|c| c.pack("U*") }.join assert_equal clusters, string.scan(/\X/).map(&:codepoints), comment end end def each_line_of_break_tests(&block) lines = 0 max_test_lines = 0 # Don't limit below 21, because that's the header of the testfile URI.parse("http://www.unicode.org/Public/#{UNICODE_VERSION}/ucd/auxiliary/GraphemeBreakTest.txt").open do |f| until f.eof? || (max_test_lines > 21 && lines > max_test_lines) lines += 1 line = f.gets.chomp! next if line.empty? || line.start_with?("#") cols, comment = line.split("#") # Cluster breaks are represented by ÷ clusters = cols.split("÷").map { |e| e.strip }.reject { |e| e.empty? } clusters = clusters.map do |cluster| # Codepoints within each cluster are separated by × codepoints = cluster.split("×").map { |e| e.strip }.reject { |e| e.empty? } # codepoints are in hex in the test suite, pack wants them as integers codepoints.map { |codepoint| codepoint.to_i(16) } end # The tests contain a solitary U+D800 <Non Private Use High # Surrogate, First> character, which Ruby does not allow to stand # alone in a UTF-8 string. So we'll just skip it. next if clusters.flatten.include?(0xd800) clusters << comment.strip yield(*clusters) end end end end ~~~ https://gist.github.com/mtsmfm/38f46882c3d4ccde35c269594fc24ebc I found an issue on Onigmo (https://github.com/k-takata/Onigmo/issues/46) but I couldn't on bugs.ruby-lang.org so I created this ticket. I'm unfamiliar with grapheme so please tell me if I get something wrong. -- https://bugs.ruby-lang.org/