operator

In this change, different parts of external data were refactored.

The goal was to make it more modular, easier to maintain and allow

higher flexibility for extension in addition to reducing code redundancy.

Change-Id: I04a8c4e494d8d1363992b6fe0bdbe6b2b3b7b767

Reviewed-on: https://asterix-gerrit.ics.uci.edu/566

Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>

Reviewed-by: Murtadha Hubail <hubailmor@gmail.com>

Change-Id: I808b6583db6b48a0e9000dcf0ac88c03c336c3a5

Reviewed-on: https://asterix-gerrit.ics.uci.edu/522

Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>

Reviewed-by: Jianfeng Jia <jianfeng.jia@gmail.com>