Imported Upstream version 2012.03.22upstream-weekly/2012.03.22

1 files changed, 34 insertions, 0 deletions

diff --git a/doc/play/sieve.go b/doc/play/sieve.go
new file mode 100644
index 000000000..585507ac4
--- /dev/null
+++ b/doc/play/sieve.go
@@ -0,0 +1,34 @@
+// A concurrent prime sieve
+
+package main
+
+// Send the sequence 2, 3, 4, ... to channel 'ch'.
+func Generate(ch chan<- int) {
+	for i := 2; ; i++ {
+		ch <- i // Send 'i' to channel 'ch'.
+	}
+}
+
+// Copy the values from channel 'in' to channel 'out',
+// removing those divisible by 'prime'.
+func Filter(in <-chan int, out chan<- int, prime int) {
+	for {
+		i := <-in // Receive value from 'in'.
+		if i%prime != 0 {
+			out <- i // Send 'i' to 'out'.
+		}
+	}
+}
+
+// The prime sieve: Daisy-chain Filter processes.
+func main() {
+	ch := make(chan int) // Create a new channel.
+	go Generate(ch)      // Launch Generate goroutine.
+	for i := 0; i < 10; i++ {
+		prime := <-ch
+		print(prime, "\n")
+		ch1 := make(chan int)
+		go Filter(ch, ch1, prime)
+		ch = ch1
+	}
+}