| // $G $D/$F.go && $L $F.$A && ./$A.out |
| |
| // 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. |
| |
| // This version generates up to 100 and checks the results. |
| // With a channel, of course. |
| |
| 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 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 Sieve(primes *chan-< int) { |
| ch := new(chan int); // Create a new channel. |
| go Generate(ch); // Start Generate() as a subprocess. |
| for { |
| prime := <-ch; |
| primes -< prime; |
| ch1 := new(chan int); |
| go Filter(ch, ch1, prime); |
| ch = ch1 |
| } |
| } |
| |
| func main() { |
| primes := new(chan int); |
| go Sieve(primes); |
| if <-primes != 2 { panic 2 } |
| if <-primes != 3 { panic 3 } |
| if <-primes != 5 { panic 5 } |
| if <-primes != 7 { panic 7 } |
| if <-primes != 11 { panic 11 } |
| if <-primes != 13 { panic 13 } |
| if <-primes != 17 { panic 17 } |
| if <-primes != 19 { panic 19 } |
| if <-primes != 23 { panic 23 } |
| if <-primes != 29 { panic 29 } |
| if <-primes != 31 { panic 31 } |
| if <-primes != 37 { panic 37 } |
| if <-primes != 41 { panic 41 } |
| if <-primes != 43 { panic 43 } |
| if <-primes != 47 { panic 47 } |
| if <-primes != 53 { panic 53 } |
| if <-primes != 59 { panic 59 } |
| if <-primes != 61 { panic 61 } |
| if <-primes != 67 { panic 67 } |
| if <-primes != 71 { panic 71 } |
| if <-primes != 73 { panic 73 } |
| if <-primes != 79 { panic 79 } |
| if <-primes != 83 { panic 83 } |
| if <-primes != 89 { panic 89 } |
| if <-primes != 97 { panic 97 } |
| sys.exit(0); |
| } |