decompose_codepoints

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 482
      def decompose_codepoints(type, codepoints)
        codepoints.inject([]) do |decomposed, cp|
          # if it's a hangul syllable starter character
          if HANGUL_SBASE <= cp and cp < HANGUL_SLAST
            sindex = cp - HANGUL_SBASE
            ncp = [] # new codepoints
            ncp << HANGUL_LBASE + sindex / HANGUL_NCOUNT
            ncp << HANGUL_VBASE + (sindex % HANGUL_NCOUNT) / HANGUL_TCOUNT
            tindex = sindex % HANGUL_TCOUNT
            ncp << (HANGUL_TBASE + tindex) unless tindex == 0
            decomposed.concat ncp
          # if the codepoint is decomposable in with the current decomposition type
          elsif (ncp = UCD[cp].decomp_mapping) and (!UCD[cp].decomp_type || type == :compatability)
            decomposed.concat decompose_codepoints(type, ncp.dup)
          else
            decomposed << cp
          end
        end
      end