def decompose_codepoints(type, codepoints)
codepoints.inject([]) do |decomposed, cp|
if HANGUL_SBASE <= cp and cp < HANGUL_SLAST
sindex = cp - HANGUL_SBASE
ncp = []
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
elsif (ncp = UCD.codepoints[cp].decomp_mapping) and (!UCD.codepoints[cp].decomp_type || type == :compatability)
decomposed.concat decompose_codepoints(type, ncp.dup)
else
decomposed << cp
end
end
end