support repetitive node topology

[Ichthyostega]

As Lumiera Architect,
I want direct support for repetitive node wiring patterns,
to avoid a dangerous leverage due to other trade-offs made within the design.

use case

Some kind of advanced multichannel media require to build essentially the same pipeline for each channel. This situation becomes virulent once some processing step is only available as simple operation on a single data stream (as opposed to being inherently capable to demultiplex and then process all parallel streams in a single operation).

the trade-off

The Node-Build collects parameter data for each port in a nested data structure on the heap and processes it recursively; the code generated in this way is highly efficient (optimiser), but is limited to a small number of ports. Increasing the number of ports and processing chains bears the danger of combinatorial explosion.

solution idea

At the level of the Fixture, a new kind of port could be introduced, designated as virtual port or patterned port. A corresponding special mark in the node invocation parameters would indicate, that the repetitive processing jobs for the channels would have to pull the same exit node, yet generate an additional channel selector parameter on-the-fly, as part of the parameter arguments passed to the node invocation. Obviously this requires that the Builder would have pre-arranged a channel selector node somewhere down the node chain to consume this channel selector parameter and deliver the data of the requested media channel up the chain.