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package pipe
import (
"sync"
)
var SinkChanError chan error
func init() {
SinkChanError = make(chan error)
go func() {
for range SinkChanError {
}
}()
}
// Proc maps cin into a channel by applying proc and outputs to its return.
func Proc[T any, V any](cin <-chan T, count int, proc func(T) (V, error)) <-chan V {
return ProcWithError(cin, SinkChanError, count, proc)
}
// ProcWithError maps cin into a channel by applying proc and outputs to its return.
func ProcWithError[T any, V any](cin <-chan T, cerr chan<- error, count int, proc func(T) (V, error)) <-chan V {
cout := make(chan V)
var wg sync.WaitGroup
for i := 0; i < count; i++ {
wg.Add(1)
go func(<-chan T, chan<- V) {
for i := range cin {
v, err := proc(i)
if err == nil {
cout <- v
} else {
cerr <- err
}
}
wg.Done()
}(cin, cout)
}
go func() {
wg.Wait()
close(cout)
}()
return cout
}
func noop[T any](_ T) {}
// Wait waits a channel to close, it ends a chain of procs.
func Wait[T any](cin <-chan T) {
for v := range cin {
noop(v)
}
}
// TailProc waits a channel to close by applying proc to it.
// It does not return a channel since its meant to end a chain of goroutine+channel.
func TailProc[T any](cin <-chan T, count int, proc func(T) error) {
TailProcWithError(cin, SinkChanError, count, proc)
}
// TailProcWithError waits a channel to close by applying proc to it.
// It does not return a channel since its meant to end a chain of goroutine+channel.
func TailProcWithError[T any](cin <-chan T, cerr chan<- error, count int, proc func(T) error) {
var wg sync.WaitGroup
for i := 0; i < count; i++ {
wg.Add(1)
go func(<-chan T) {
for i := range cin {
if err := proc(i); err != nil {
cerr <- err
}
}
wg.Done()
}(cin)
}
wg.Wait()
}
func TailReduce[T any, V any](cin <-chan T, red func(V, T) (V, error), vinit V) V {
return TailReduceWithError(cin, SinkChanError, red, vinit)
}
func TailReduceWithError[T any, V any](cin <-chan T, cerr chan<- error, red func(V, T) (V, error), vinit V) V {
acc := vinit
for i := range cin {
if a, err := red(acc, i); err != nil {
cerr <- err
} else {
acc = a
}
}
return acc
}
// Yield returna a channel from a slice.
// It will pipe in into a chan returned by the function.
func Yield[T any](in []T) <-chan T {
cout := make(chan T)
go func(chan<- T) {
for _, a := range in {
cout <- a
}
close(cout)
}(cout)
return cout
}
// Map is a classic map.
// It gets vs apply m to it and return its value n times.
func Map[T any, V any](m func(T) V, vs []T) []V {
result := make([]V, len(vs))
for i, v := range vs {
result[i] = m(v)
}
return result
}
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