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Diffstat (limited to 'doc/progs/sieve.go')
-rw-r--r-- | doc/progs/sieve.go | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/doc/progs/sieve.go b/doc/progs/sieve.go new file mode 100644 index 000000000..b31530981 --- /dev/null +++ b/doc/progs/sieve.go @@ -0,0 +1,38 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package main + +import "fmt" + +// 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, out chan int, prime int) { + for { + i := <-in // Receive value of new variable 'i' from 'in'. + if i%prime != 0 { + out <- i // Send 'i' to channel 'out'. + } + } +} + +// The prime sieve: Daisy-chain filter processes together. +func main() { + ch := make(chan int) // Create a new channel. + go generate(ch) // Start generate() as a goroutine. + for i := 0; i < 100; i++ { // Print the first hundred primes. + prime := <-ch + fmt.Println(prime) + ch1 := make(chan int) + go filter(ch, ch1, prime) + ch = ch1 + } +} |