ANT string manipulating

i'm using the following Ant script to check a string and create another string based on it.

ex: subversao = 4.2.1  and my new string(versao) will be 4.2


<loadresource property="versao">
    <string value="${subversao}"/>
        <filterchain>
            <tokenfilter>
              <replaceregex pattern="(.*)\.[^\.]+" replace="\1"/>
            </tokenfilter>
        </filterchain>
    </loadresource>

And now i want to be able to write 4.2.1 or 4.2.1-something-0.0.2 and still be able to get the 4.2 out of it.