LowerCaseTokenizer performs the function of LetterTokenizer
and LowerCaseFilter together. It divides text at non-letters and converts
them to lower case. While it is functionally equivalent to the combination
of LetterTokenizer and LowerCaseFilter, there is a performance advantage
to doing the two tasks at once, hence this (redundant) implementation.
Note: this does a decent job for most European languages, but does a terrible
job for some Asian languages, where words are not separated by spaces. |