Looks OK to me. Paul.
On Aug 8, 2012, at 11:58 PM, Xueming Shen <xueming.s...@oracle.com> wrote: > Hi > > It appears the optimization (flatten a binary tree structure into a branch/ > switch) we put into JDK6 for alternation operation [1] has problem if the > first construct is a group "(...)" followed by a greedy/reluctant "once or not > at all" quantifier. For example regex "(a)?bc|d" or "(a)??bc|d" can't be found > for input "d", while "a?bc|d" or "a??bc|d" just works fine. > > The root cause is that expr() mistakenly to use the Branch node from the > sub-expression (in above case, the branch node for "(a)?" instead of using > its own Branch node (because the incorrect use of "prev instance of Branch", > see the diff), which basically messes up the internal regex node tree [2] > > The webrev is at > http://cr.openjdk.java.net/~sherman/7189363/webrev > > Thanks, > -Sherman > > PS: > I'm surprised this bug has not been noticed until now. One of the reasons is > that the "messed up" regex node tree actually works for most of the cases > for this particular regex, for example > > Pattern.compile("(a)?bc|d").matcher("d").matches() > Pattern.compile("(a)?bc|d").matcher("bc").matches() > Pattern.compile("(a)?bc|d").matcher("abc").matches() > and even > Pattern.compile("(a)?bc|de").matcher("de").find() > > all return true. The "find()" for single "d" fails only because the "minimum > length" check (see [2] for details, if interested) > > [1] http://cr.openjdk.java.net/~sherman/5013651_6271399_6342544/ > [2] http://cr.openjdk.java.net/~sherman/7189363/nodes
