channelmerge.go

package main

import (
	"fmt"
)

// fillChannel simply fills the channel with i, i+2, i+4, ...
func fillChannel(ch chan int, i int) {
	for {
		ch <- i
		i += 2
	}
}

// evenChannel returns a channel which has all the even positive integers
func evenChannel() <-chan int {
	evens := make(chan int)
	go fillChannel(evens, 0)
	return evens
}

// evenChannel returns a channel which has all the odd positive integers
func oddChannel() <-chan int {
	odds := make(chan int)
	go fillChannel(odds, 1)
	return odds
}

// mergeChannels takes a slice of channels, returns a channel which is the
// n-way-merge of all channels from the input
func mergeChannels(channels []<-chan int) <-chan int {
	merged := make(chan int)
	for _, ch := range channels {
		go func(c <-chan int) {
			for incoming := range c {
				// process incoming value if needed.
				merged <- incoming
			}
		}(ch)
	}
	return merged
}

func main() {

	// merging odd and even channels will give us all the integers
	integers := mergeChannels([]<-chan int{
		evenChannel(),
		oddChannel(),
	})

	// let's print them out.
	for i := range integers {
		fmt.Println(i)
	}
}