http://www.pcre.org/pcre.txt
http://www.pcre.org/pcre.txt
in UTF-8 mode, characters with values greater than 128 do
not match any of the POSIX character classes. However, if the PCRE_UCP
option is passed to pcre_compile(), some of the classes are changed so
that Unicode character properties are used. This is achieved by replac-
ing the POSIX classes by other sequences, as follows:
[:alnum:] becomes \p{Xan}
[:alpha:] becomes \p{L}
[:blank:] becomes \h
[:digit:] becomes \p{Nd}
[:lower:] becomes \p{Ll}
[:space:] becomes \p{Xps}
[:upper:] becomes \p{Lu}
[:word:] becomes \p{Xwd}
memo
