find what [[:space:]] really is
#!/usr/bin/env ruby
(0...1114112).each do |i|
next if (0xD800..0xDFFF).include?(i) # surrogate area
str = [i].pack('U*')
if str.match(/[[:space:]]/)
p [i, str]
end
end
__END__
# output as follows:
[9, "\t"]
[10, "\n"]
[11, "\v"]
[12, "\f"]
[13, "\r"]
[32, " "]
[133, "
"]
[160, " "]
[5760, " "]
[8192, " "]
[8193, " "]
[8194, " "]
[8195, " "]
[8196, " "]
[8197, " "]
[8198, " "]
[8199, " "]
[8200, " "]
[8201, " "]
[8202, " "]
[8232, "\u2028"]
[8233, "\u2029"]
[8239, " "]
[8287, " "]
[12288, " "]