[FLINK-7292] Fix EMPTY MATCH bug in CEP.

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: Library / CEP
• Assignee: Unassigned
• Reporter: zhangxiaoyu
• Created: 28/Jul/17 12:32
• Updated: 12/Oct/17 10:04
• Resolved: 12/Oct/17 10:04

Description

Currently, with the pattern

a?

and the event

a1

, the result pattern is only

a1

without the empty match.
We wish the empty matched is also returned. And I am working on this issue now.

My method is checking if there exists empty match only when the the first event comes(at the StartState) ——try to traverse the PROCEED edges with the trueFunction condition from the StartState, see if it can arrive FinalState, if so, add an empty list to the result.