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iterable: expose iterFunc as iterable.Func

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Fixes #483.

R=dsymonds, dsymonds1
CC=golang-dev
https://golang.org/cl/965044
This commit is contained in:
Russ Cox 2010-04-27 18:48:29 -07:00
parent 9c8cee712d
commit 01fc062496
1 changed files with 17 additions and 16 deletions
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33
src/pkg/exp/iterable/iterable.go
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@ -133,14 +133,15 @@ func Partition(iter Iterable, f func(interface{}) bool) (Iterable, Iterable) {
return Filter(iter, f), Filter(iter, not(f)) return Filter(iter, f), Filter(iter, not(f))
} }
// helper type for the Take/TakeWhile/Drop/DropWhile functions. // A Func is a function that, when called, sends the
// primarily used so that the .Iter() method can be attached // iterable values on a channel.
type iterFunc func(chan<- interface{}) type Func func(chan<- interface{})
// provide the Iterable interface // Iter creates and returns a new channel; it starts a
func (v iterFunc) Iter() <-chan interface{} { // goroutine running f to send values to the channel.
func (f Func) Iter() <-chan interface{} {
ch := make(chan interface{}) ch := make(chan interface{})
go v(ch) go f(ch)
return ch return ch
} }
@ -149,7 +150,7 @@ func Take(iter Iterable, n int) Iterable { return Slice(iter, 0, n) }
// TakeWhile returns an Iterable that contains elements from iter while f is true. // TakeWhile returns an Iterable that contains elements from iter while f is true.
func TakeWhile(iter Iterable, f func(interface{}) bool) Iterable { func TakeWhile(iter Iterable, f func(interface{}) bool) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
for v := range iter.Iter() { for v := range iter.Iter() {
if !f(v) { if !f(v) {
break break
@ -162,7 +163,7 @@ func TakeWhile(iter Iterable, f func(interface{}) bool) Iterable {
// Drop returns an Iterable that returns each element of iter after the first n elements. // Drop returns an Iterable that returns each element of iter after the first n elements.
func Drop(iter Iterable, n int) Iterable { func Drop(iter Iterable, n int) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
m := n m := n
for v := range iter.Iter() { for v := range iter.Iter() {
if m > 0 { if m > 0 {
@ -177,7 +178,7 @@ func Drop(iter Iterable, n int) Iterable {
// DropWhile returns an Iterable that returns each element of iter after the initial sequence for which f returns true. // DropWhile returns an Iterable that returns each element of iter after the initial sequence for which f returns true.
func DropWhile(iter Iterable, f func(interface{}) bool) Iterable { func DropWhile(iter Iterable, f func(interface{}) bool) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
drop := true drop := true
for v := range iter.Iter() { for v := range iter.Iter() {
if drop { if drop {
@ -194,7 +195,7 @@ func DropWhile(iter Iterable, f func(interface{}) bool) Iterable {
// Cycle repeats the values of iter in order infinitely. // Cycle repeats the values of iter in order infinitely.
func Cycle(iter Iterable) Iterable { func Cycle(iter Iterable) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
for { for {
for v := range iter.Iter() { for v := range iter.Iter() {
ch <- v ch <- v
@ -205,7 +206,7 @@ func Cycle(iter Iterable) Iterable {
// Chain returns an Iterable that concatentates all values from the specified Iterables. // Chain returns an Iterable that concatentates all values from the specified Iterables.
func Chain(args []Iterable) Iterable { func Chain(args []Iterable) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
for _, e := range args { for _, e := range args {
for v := range e.Iter() { for v := range e.Iter() {
ch <- v ch <- v
@ -219,7 +220,7 @@ func Chain(args []Iterable) Iterable {
// each input Iterable. The length of the returned Iterable is the minimum of // each input Iterable. The length of the returned Iterable is the minimum of
// the lengths of the input Iterables. // the lengths of the input Iterables.
func Zip(args []Iterable) Iterable { func Zip(args []Iterable) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
defer close(ch) defer close(ch)
if len(args) == 0 { if len(args) == 0 {
return return
@ -260,7 +261,7 @@ func ZipWith3(f func(d, e, f interface{}) interface{}, a, b, c Iterable) Iterabl
// Slice returns an Iterable that contains the elements from iter // Slice returns an Iterable that contains the elements from iter
// with indexes in [start, stop). // with indexes in [start, stop).
func Slice(iter Iterable, start, stop int) Iterable { func Slice(iter Iterable, start, stop int) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
defer close(ch) defer close(ch)
i := 0 i := 0
for v := range iter.Iter() { for v := range iter.Iter() {
@ -277,7 +278,7 @@ func Slice(iter Iterable, start, stop int) Iterable {
// Repeat generates an infinite stream of v. // Repeat generates an infinite stream of v.
func Repeat(v interface{}) Iterable { func Repeat(v interface{}) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
for { for {
ch <- v ch <- v
} }
@ -286,7 +287,7 @@ func Repeat(v interface{}) Iterable {
// RepeatTimes generates a stream of n copies of v. // RepeatTimes generates a stream of n copies of v.
func RepeatTimes(v interface{}, n int) Iterable { func RepeatTimes(v interface{}, n int) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
for i := 0; i < n; i++ { for i := 0; i < n; i++ {
ch <- v ch <- v
} }
@ -315,7 +316,7 @@ type Grouper interface {
// values for the group, and an Iterable for retrieving all the values in the // values for the group, and an Iterable for retrieving all the values in the
// group. // group.
func GroupBy(iter Iterable, k Grouper) Iterable { func GroupBy(iter Iterable, k Grouper) Iterable {
return iterFunc(func(ch chan<- interface{}) { return Func(func(ch chan<- interface{}) {
var curkey interface{} var curkey interface{}
var lst *list.List var lst *list.List
// Basic strategy is to read one group at a time into a list prior to emitting the Group value // Basic strategy is to read one group at a time into a list prior to emitting the Group value