added buffer argument to OfSeq and OfSeq2

- ToMapSuccessive introduced which still uses old behavior

chan_io.go

@@ -21,9 +21,12 @@ func WriteIntoDelayed[T any](ch chan<- T, delay time.Duration, values ...T) {
 
 // WriteIntoWriter reads all values from ch and writes them via fmt.Fprintln to all writers
 func WriteIntoWriter[T any](ch <-chan T, writers ...io.Writer) {
-	for value := range ch {
-		for _, w := range writers {
-			fmt.Fprintln(w, value)
+	w := io.MultiWriter(writers...)
+	EachSuccessive(ch, func(value T) {
+		if err, ok := any(value).(error); ok {
+			fmt.Fprintln(w, err.Error())
+			return
 		}
-	}
+		fmt.Fprintln(w, value)
+	})
 }

each.go

@@ -0,0 +1,34 @@
+package channel
+
+import "sync"
+
+// Each consumes all values and calls f for each of them.
+// It blocks until source is closed
+func Each[T any](source <-chan T, f func(T)) {
+	EachWithRunner(source, getDefaultRunner(), f)
+}
+
+// Each consumes all values and calls f for each of them.
+// It blocks until source is closed
+func EachWithRunner[T any](source <-chan T, runner Runner, f func(T)) {
+	wg := &sync.WaitGroup{}
+
+	for value := range source {
+		value := value
+		wg.Add(1)
+		runner.Run(func() {
+			defer wg.Done()
+			f(value)
+		})
+	}
+
+	wg.Wait()
+}
+
+// EachSuccessive consumes all values and calls f for each of them.
+// It blocks until source is closed
+func EachSuccessive[T any](source <-chan T, f func(T)) {
+	for value := range source {
+		f(value)
+	}
+}

filter.go

@@ -0,0 +1,39 @@
+package channel
+
+func FilterSuccessive[T any](source <-chan T, filter func(T) bool) <-chan T {
+	out := make(chan T, cap(source))
+
+	go func() {
+		defer close(out)
+		for value := range source {
+			if filter(value) {
+				out <- value
+			}
+		}
+	}()
+
+	return out
+}
+
+func Filter[T any](source <-chan T, filter func(T) bool) <-chan T {
+	return FilterPreserveOrderWithRunner(source, getDefaultRunner(), filter)
+}
+
+func FilterPreserveOrderWithRunner[T any](source <-chan T, runner Runner, filter func(T) bool) <-chan T {
+	type FilteredValue[T any] struct {
+		Value  T
+		Filter bool
+	}
+
+	mappedValues := MapPreserveOrderWithRunner(source, runner, func(value T) FilteredValue[T] {
+		return FilteredValue[T]{Value: value, Filter: filter(value)}
+	})
+
+	filteredValues := FilterSuccessive(mappedValues, func(filteredValue FilteredValue[T]) bool {
+		return filteredValue.Filter
+	})
+
+	return MapSuccessive(filteredValues, func(filteredValue FilteredValue[T]) T {
+		return filteredValue.Value
+	})
+}

find.go

@@ -0,0 +1,38 @@
+package channel
+
+import "context"
+
+func FindFirst[T any](source <-chan T) *T {
+	for v := range source {
+		return &v
+	}
+	return nil
+}
+
+func FindFirstAndCancel[T any](source <-chan T, cancel context.CancelFunc) *T {
+	defer cancel()
+	for v := range source {
+		return &v
+	}
+	return nil
+}
+
+func FindLast[T any](source <-chan T) *T {
+	var last *T = new(T)
+	found := false
+
+	for v := range source {
+		*last = v
+		found = true
+	}
+
+	if !found {
+		return nil
+	}
+
+	return last
+}
+
+func HasAny[T any](source <-chan T) bool {
+	return FindFirst(source) != nil
+}

flat.go

@@ -0,0 +1,46 @@
+package channel
+
+func FlatSlice[T any](source <-chan []T) <-chan T {
+	out := make(chan T, cap(source))
+
+	go func() {
+		defer close(out)
+		for slice := range source {
+			for _, v := range slice {
+				out <- v
+			}
+		}
+	}()
+
+	return out
+}
+
+func FlatMap[K comparable, V, T any](source <-chan map[K]V, unmapper func(key K, value V) T) <-chan T {
+	out := make(chan T, cap(source))
+
+	go func() {
+		defer close(out)
+		for slice := range source {
+			for k, v := range slice {
+				out <- unmapper(k, v)
+			}
+		}
+	}()
+
+	return out
+}
+
+func FlatChan[T any](source <-chan <-chan T) <-chan T {
+	out := make(chan T, cap(source))
+
+	go func() {
+		defer close(out)
+		for ch := range source {
+			for v := range ch {
+				out <- v
+			}
+		}
+	}()
+
+	return out
+}

go.mod

@@ -1,3 +1,3 @@
-module git.tordarus.net/Tordarus/channel
+module git.milar.in/milarin/channel
 
-go 1.18
+go 1.23

internal_stuff.go

@@ -0,0 +1,12 @@
+package channel
+
+import "runtime"
+
+type mapEntry[K comparable, V any] struct {
+	Key   K
+	Value V
+}
+
+func getDefaultRunner() Runner {
+	return NewLimitedRunner(runtime.NumCPU())
+}

limited_runner.go

@@ -22,7 +22,7 @@ func NewLimitedRunner(routineLimit int) *LimitedRunner {
 func (r *LimitedRunner) Run(f func()) {
 	r.limiter <- struct{}{}
 	go func() {
+		defer func() { <-r.limiter }()
 		f()
-		<-r.limiter
 	}()
 }

map.go

@@ -1,13 +1,15 @@
 package channel
 
-// MapParallel applies mapper to all I's coming from in and sends their return values to out while conserving input order.
-// All mappings will be done as concurrently as possible
-func MapParallel[I, O any](source <-chan I, mapper func(I) O) (out <-chan O) {
-	return MapParallelWithRunner(source, NewUnlimitedRunner(), mapper)
+import "sync"
+
+// MapPreserveOrder applies mapper to all I's coming from source and sends their return values to out while preserving input order.
+// All mappings will be done as concurrently as possible using as many threads as there are CPU cores
+func MapPreserveOrder[I, O any](source <-chan I, mapper func(I) O) (out <-chan O) {
+	return MapPreserveOrderWithRunner(source, getDefaultRunner(), mapper)
 }
 
-// MapParallelWithRunner behaves like MapParallel but uses runner to spawn its routines
-func MapParallelWithRunner[I, O any](source <-chan I, runner Runner, mapper func(I) O) <-chan O {
+// MapPreserveOrderWithRunner behaves like MapPreserveOrder but uses runner to spawn its routines
+func MapPreserveOrderWithRunner[I, O any](source <-chan I, runner Runner, mapper func(I) O) <-chan O {
 	out := make(chan O, cap(source))
 	outchannels := make(chan chan O, cap(source))
 
@@ -39,9 +41,38 @@ func MapParallelWithRunner[I, O any](source <-chan I, runner Runner, mapper func
 	return out
 }
 
-// Map applies mapper to all I's coming from in and sends their return values to out while conserving input order.
-// All mappings will be done successively
+// Map applies mapper to all I's coming from source and sends their return values to out.
+// All mappings will be done as concurrently as possible using as many threads as there are CPU cores
 func Map[I, O any](source <-chan I, mapper func(I) O) <-chan O {
+	return MapWithRunner(source, getDefaultRunner(), mapper)
+}
+
+// MapWithRunner behaves like Map but uses runner to spawn its routines
+func MapWithRunner[I, O any](source <-chan I, runner Runner, mapper func(I) O) <-chan O {
+	out := make(chan O, cap(source))
+
+	go func() {
+		defer close(out)
+		wg := &sync.WaitGroup{}
+
+		for value := range source {
+			value := value
+			wg.Add(1)
+			runner.Run(func() {
+				defer wg.Done()
+				out <- mapper(value)
+			})
+		}
+
+		wg.Wait()
+	}()
+
+	return out
+}
+
+// MapSuccessive applies mapper to all I's coming from source and sends their return values to out while preserving input order.
+// All mappings will be done successively in a single thread
+func MapSuccessive[I, O any](source <-chan I, mapper func(I) O) <-chan O {
 	out := make(chan O, cap(source))
 
 	go func() {

of.go

@@ -2,6 +2,7 @@ package channel
 
 import (
 	"context"
+	"iter"
 	"time"
 )
 
@@ -51,3 +52,48 @@ func OfFunc[T any](ctx context.Context, buffer int, f func() T) <-chan T {
 
 	return out
 }
+
+// OfMap returns a channel containing the return values of the unmapper function
+// applied to any key-value pair in m
+// The order is random
+func OfMap[K comparable, V, T any](m map[K]V, unmapper func(K, V) T) <-chan T {
+	out := make(chan T, len(m))
+
+	go func() {
+		defer close(out)
+		for k, v := range m {
+			out <- unmapper(k, v)
+		}
+	}()
+
+	return out
+}
+
+// OfSeq returns a channel containing all values provided by the iterator
+func OfSeq[T any](seq iter.Seq[T], buffer int) <-chan T {
+	out := make(chan T, buffer)
+
+	go func() {
+		defer close(out)
+		for v := range seq {
+			out <- v
+		}
+	}()
+
+	return out
+}
+
+// OfSeq2 returns a channel containing the return values of the unmapper function
+// when provided with the values of the iterator
+func OfSeq2[K comparable, V, T any](seq iter.Seq2[K, V], buffer int, unmapper func(K, V) T) <-chan T {
+	out := make(chan T, buffer)
+
+	go func() {
+		defer close(out)
+		for key, value := range seq {
+			out <- unmapper(key, value)
+		}
+	}()
+
+	return out
+}

result.go

@@ -0,0 +1,102 @@
+package channel
+
+type Result[T any] struct {
+	value *T
+	err   error
+}
+
+func ResultOf[T any](value T, err error) Result[T] {
+	if err != nil {
+		return Result[T]{value: nil, err: err}
+	}
+
+	return Result[T]{value: &value, err: nil}
+}
+
+func WrapResultOutputFunc[I, O any](f func(I) (O, error)) func(I) Result[O] {
+	return func(i I) Result[O] { return ResultOf(f(i)) }
+}
+
+func WrapResultFunc[I, O any](f func(I) (O, error)) func(Result[I]) Result[O] {
+	resFunc := WrapResultOutputFunc(f)
+	nilValue := *new(O)
+	return func(r Result[I]) Result[O] {
+		v, err := r.Get()
+		if err != nil {
+			return ResultOf(nilValue, err)
+		}
+		return resFunc(v)
+	}
+}
+
+func (r Result[T]) Success() bool {
+	return r.err == nil
+}
+
+func (r Result[T]) Fail() bool {
+	return !r.Success()
+}
+
+func (r Result[T]) GetOrDefault(defaultValue T) T {
+	if r.Fail() {
+		return defaultValue
+	}
+
+	return *r.value
+}
+
+func (r Result[T]) Get() (T, error) {
+	if r.err != nil {
+		return *new(T), r.err
+	}
+	return *r.value, r.err
+}
+
+func (r Result[T]) GetUnsafe() T {
+	if r.err != nil {
+		panic(r.err)
+	}
+	return *r.value
+}
+
+func (r Result[T]) Err() error {
+	return r.err
+}
+
+func FilterSuccess[T any](source <-chan Result[T]) <-chan T {
+	succeeded := Filter(source, Result[T].Success)
+
+	return MapSuccessive(succeeded, func(r Result[T]) T {
+		v, _ := r.Get()
+		return v
+	})
+}
+
+func FilterFail[T any](source <-chan Result[T]) <-chan T {
+	failed := Filter(source, Result[T].Fail)
+
+	return MapSuccessive(failed, func(r Result[T]) T {
+		v, _ := r.Get()
+		return v
+	})
+}
+
+func FilterResults[T any](source <-chan Result[T]) (succeeded <-chan T, failed <-chan error) {
+	succ := make(chan T, cap(source))
+	fail := make(chan error, cap(source))
+
+	go func() {
+		defer close(succ)
+		defer close(fail)
+
+		for r := range source {
+			if r.Fail() {
+				fail <- r.Err()
+				continue
+			}
+			succ <- r.GetUnsafe()
+		}
+	}()
+
+	return succ, fail
+}

tee.go

@@ -0,0 +1,37 @@
+package channel
+
+// Tee returns 2 channels which both receive all values from source.
+// It's basically a copy function for channels
+func Tee[T any](source <-chan T) (<-chan T, <-chan T) {
+	outs := TeeMany(source, 2)
+	return outs[0], outs[1]
+}
+
+// TeeMany returns a given amount of channels which all receive all values from source.
+// It's basically a copy function for channels
+func TeeMany[T any](source <-chan T, amount int) []<-chan T {
+	outputs := make([]chan T, amount)
+	for i := range outputs {
+		outputs[i] = make(chan T, cap(source))
+	}
+
+	go func() {
+		defer func() {
+			for _, out := range outputs {
+				close(out)
+			}
+		}()
+
+		for value := range source {
+			for _, out := range outputs {
+				out <- value
+			}
+		}
+	}()
+
+	readOnlyOutputs := make([]<-chan T, 0, amount)
+	for _, out := range outputs {
+		readOnlyOutputs = append(readOnlyOutputs, out)
+	}
+	return readOnlyOutputs
+}

timeout.go

@@ -3,7 +3,8 @@ package channel
 import "time"
 
 // CloseOnTimeout returns a channel which receives all values from the source.
-// If no value was received in the given timeout duration, the returned channel will be closed
+// If no value was received in the given timeout duration, the returned channel will be closed.
+// The input channel will not be closed.
 func CloseOnTimeout[T any](source <-chan T, timeout time.Duration) <-chan T {
 	output := make(chan T, cap(source))
 

to.go

@@ -5,16 +5,32 @@ import "container/list"
 // ToSlice returns a slice containing all values read from ch
 func ToSlice[T any](ch <-chan T) []T {
 	s := make([]T, 0, cap(ch))
-	Each(ch, func(value T) { s = append(s, value) })
+	EachSuccessive(ch, func(value T) { s = append(s, value) })
 	return s
 }
 
+// ToSliceContinuous returns a slice containing all values read from ch.
+// The returned slice will be a pointer slice to a continuous block of memory.
+// All values will be copied.
+func ToSliceContinuous[T any](ch <-chan *T) []*T {
+	values := make([]T, 0, cap(ch))
+	pointers := make([]*T, 0, cap(ch))
+	EachSuccessive(ch, func(value *T) {
+		pointers = append(pointers, value)
+
+		if value != nil {
+			values = append(values, *value)
+		}
+	})
+	return pointers
+}
+
 // ToSliceDeref returns a slice containing all values read from ch.
 // The returned slice will be a dereferenced and continuous block of memory.
 // Nil pointers are ignored.
 func ToSliceDeref[T any](ch <-chan *T) []T {
 	s := make([]T, 0, cap(ch))
-	Each(ch, func(value *T) {
+	EachSuccessive(ch, func(value *T) {
 		if value != nil {
 			s = append(s, *value)
 		}
@@ -25,28 +41,44 @@ func ToSliceDeref[T any](ch <-chan *T) []T {
 // ToList returns a list.List containing all values read from ch
 func ToList[T any](ch <-chan T) *list.List {
 	l := list.New()
-	Each(ch, func(value T) { l.PushBack(value) })
+	EachSuccessive(ch, func(value T) { l.PushBack(value) })
 	return l
 }
 
 // ToMap returns a map containing all values read from ch.
-// The map keys are determined by f
-func ToMap[K comparable, V any](ch <-chan V, f func(V) K) map[K]V {
-	m := map[K]V{}
-	Each(ch, func(value V) { m[f(value)] = value })
-	return m
+// The map key-value pairs are determined by f which will be called as concurrently as possible
+// to build the resulting map
+func ToMap[T any, K comparable, V any](ch <-chan T, f func(T) (K, V)) map[K]V {
+	return ToMapWithRunner(ch, getDefaultRunner(), f)
 }
 
-// ToKeyMap returns a map containing all values read from ch as keys.
-// The map values are determined by f
-func ToKeyMap[K comparable, V any](ch <-chan K, f func(K) V) map[K]V {
+// ToMap returns a map containing all values read from ch.
+// The map key-value pairs are determined by f which will be called as concurrently as possible
+// to build the resulting map
+func ToMapWithRunner[T any, K comparable, V any](ch <-chan T, runner Runner, f func(T) (K, V)) map[K]V {
+	map2entry := func(t T) mapEntry[K, V] {
+		k, v := f(t)
+		return mapEntry[K, V]{Key: k, Value: v}
+	}
+
+	map2kv := func(e mapEntry[K, V]) (K, V) { return e.Key, e.Value }
+
+	return ToMapSuccessive(MapWithRunner(ch, runner, map2entry), map2kv)
+}
+
+// ToMapSuccessive returns a map containing all values read from ch.
+// The map key-value pairs are determined by f
+func ToMapSuccessive[T any, K comparable, V any](ch <-chan T, f func(T) (K, V)) map[K]V {
 	m := map[K]V{}
-	Each(ch, func(key K) { m[key] = f(key) })
+	EachSuccessive(ch, func(value T) {
+		k, v := f(value)
+		m[k] = v
+	})
 	return m
 }
 
 // ToStructMap returns a struct{} map containing all values read from ch as keys.
-// It is a shorthand for ToKeyMap(ch, func(k K) struct{} { return struct{}{} })
+// It is a shorthand for ToMap(ch, func(value T) (T, struct{}) { return value, struct{}{} })
 func ToStructMap[T comparable](ch <-chan T) map[T]struct{} {
-	return ToKeyMap(ch, func(key T) struct{} { return struct{}{} })
+	return ToMap(ch, func(value T) (T, struct{}) { return value, struct{}{} })
 }

utils.go

@@ -5,53 +5,11 @@ func determineBufferSize[T any](channels []<-chan T) int {
 		return 0
 	}
 
-	bufSize := 0
+	maxBufSize := 0
 	for _, ch := range channels {
-		bufSize += cap(ch)
-	}
-	return bufSize / len(channels)
-}
-
-// Flush consumes all values and discards them immediately.
-// It blocks until all sources are closed
-func Flush[T any](sources ...<-chan T) {
-	for range Merge(sources...) {
-	}
-}
-
-// Each consumes all values and calls f for each of them.
-// It blocks until all sources are closed
-func Each[T any](source <-chan T, f func(T)) {
-	for value := range source {
-		f(value)
-	}
-}
-
-// Tee returns 2 channels which both receive all values from source.
-// Its basically a copy function for channels
-func Tee[T any](source <-chan T) (<-chan T, <-chan T) {
-	outs := TeeMany(source, 2)
-	return outs[0], outs[1]
-}
-
-// TeeMany returns a given amount of channels which all receive all values from source.
-// Its basically a copy function for channels
-func TeeMany[T any](source <-chan T, amount int) []<-chan T {
-	outs := make([]chan T, amount)
-
-	go func() {
-		defer func() {
-			for _, out := range outs {
-				close(out)
-			}
-		}()
-
-		for value := range source {
-			for _, out := range outs {
-				out <- value
-			}
+		if cap(ch) > maxBufSize {
+			maxBufSize = cap(ch)
 		}
-	}()
-
-	return (interface{}(outs)).([]<-chan T)
+	}
+	return maxBufSize
 }