This makes both the Pattern and the Matcher class abstract so that more
specialized patterns than the trivial patterns we support so far can be
implemented as convenient subclasses of the respective abstract base
classes.
To ease development, we work on copies in test/regex/ in the 'regex'
package. That way, it can be developed in Eclipse (because it does not
interfere with Oracle JRE's java.util.regex.* classes).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
