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/**
* Copyright (c) 2016-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
package main
import (
"sync"
)
//
// Filter data on input channel
//
func filter(f func(interface{}) bool, in chan interface{}) chan interface{} {
out := make(chan interface{})
go func() {
for val := range in {
if f(val) {
out <- val
}
}
}()
return out
}
//
// fork input channel into two, copy data
//
func fork(in <-chan interface{}) (out1, out2 chan interface{}) {
out1, out2 = make(chan interface{}), make(chan interface{})
go func() {
for val := range in {
out1 <- val
out2 <- val
}
}()
return
}
//
// Merge data from multiple channels into one
//
func merge(cs ...chan interface{}) chan interface{} {
var wg sync.WaitGroup
out := make(chan interface{})
output := func(c <-chan interface{}) {
defer wg.Done()
for val := range c {
out <- val
}
}
wg.Add(len(cs))
for _, ch := range cs {
go output(ch)
}
go func() {
wg.Wait()
close(out)
}()
return out
}
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