grep_connection_impl
====================

Treats the source output pattern as a regex that is applied to the dimension
names of the target input representation.  Elements with matching dimension
names are set to `high_value` and the rest to `low_value`.  If the source
output is empty, then the target input is set to zero.

Parameters
----------

	parameter	default_value
	low_value	-1
	high_value	1