huge-csv-5.go

func joiner(metadata, setIDs <-chan *line, out chan<- *line) {
	defer close(out) // close channel on return

	si := &line{}
	for md := range metadata {
		sep := ","
		// add matching strength set (if left over from previous iteration)
		if si.id == md.id {
			md.restOfLine += sep + si.restOfLine
			sep = " "
		}
		// look for matching strength sets
		for si = range setIDs {
			// add all strength sets with matching IDs
			if si.id == md.id {
				md.restOfLine += sep + si.restOfLine
				sep = " "
			} else if si.id > md.id {
				break
			}
			// skip all strength sets with lower IDs
		}
		// send the augmented line into the channel
		out <- md
	}
}