mirror of
https://github.com/golang/go
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73 lines
1.9 KiB
Go
73 lines
1.9 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This version generates up to 100 and checks the results.
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// With a channel, of course.
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package main
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// Send the sequence 2, 3, 4, ... to channel 'ch'.
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func Generate(ch *chan-< int) {
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for i := 2; ; i++ {
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ch -< i // Send 'i' to channel 'ch'.
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}
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}
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// Copy the values from channel 'in' to channel 'out',
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// removing those divisible by 'prime'.
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func Filter(in *chan<- int, out *chan-< int, prime int) {
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for {
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i := <-in // Receive value of new variable 'i' from 'in'.
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if i % prime != 0 {
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out -< i // Send 'i' to channel 'out'.
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}
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}
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}
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// The prime sieve: Daisy-chain Filter processes together.
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func Sieve(primes *chan-< int) {
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ch := new(chan int); // Create a new channel.
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go Generate(ch); // Start Generate() as a subprocess.
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for {
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prime := <-ch;
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primes -< prime;
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ch1 := new(chan int);
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go Filter(ch, ch1, prime);
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ch = ch1
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}
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}
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func main() {
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primes := new(chan int);
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go Sieve(primes);
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if <-primes != 2 { panic 2 }
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if <-primes != 3 { panic 3 }
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if <-primes != 5 { panic 5 }
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if <-primes != 7 { panic 7 }
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if <-primes != 11 { panic 11 }
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if <-primes != 13 { panic 13 }
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if <-primes != 17 { panic 17 }
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if <-primes != 19 { panic 19 }
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if <-primes != 23 { panic 23 }
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if <-primes != 29 { panic 29 }
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if <-primes != 31 { panic 31 }
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if <-primes != 37 { panic 37 }
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if <-primes != 41 { panic 41 }
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if <-primes != 43 { panic 43 }
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if <-primes != 47 { panic 47 }
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if <-primes != 53 { panic 53 }
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if <-primes != 59 { panic 59 }
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if <-primes != 61 { panic 61 }
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if <-primes != 67 { panic 67 }
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if <-primes != 71 { panic 71 }
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if <-primes != 73 { panic 73 }
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if <-primes != 79 { panic 79 }
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if <-primes != 83 { panic 83 }
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if <-primes != 89 { panic 89 }
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if <-primes != 97 { panic 97 }
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sys.exit(0);
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}
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