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// $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<100; 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);
}
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