From 018426e83afde121843b3731ca5d7dcbe33a17e0 Mon Sep 17 00:00:00 2001
From: tkms0106 <23391543+tkms0106@users.noreply.github.com>
Date: Mon, 14 Sep 2020 20:12:34 +0900
Subject: [PATCH] Add repeatFn sample

4. Concurrency Patterns in Go
->Pipelines
->Some Handy Generators
---
 .../fig-take-and-repeatfn-pipeline.go         | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 concurrency-patterns-in-go/pipelines/some-handy-generators/fig-take-and-repeatfn-pipeline.go

diff --git a/concurrency-patterns-in-go/pipelines/some-handy-generators/fig-take-and-repeatfn-pipeline.go b/concurrency-patterns-in-go/pipelines/some-handy-generators/fig-take-and-repeatfn-pipeline.go
new file mode 100644
index 0000000..079093c
--- /dev/null
+++ b/concurrency-patterns-in-go/pipelines/some-handy-generators/fig-take-and-repeatfn-pipeline.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+)
+
+func main() {
+	repeatFn := func(
+		done <-chan interface{},
+		fn func() interface{},
+	) <-chan interface{} {
+		valueStream := make(chan interface{})
+		go func() {
+			defer close(valueStream)
+			for {
+				select {
+				case <-done:
+					return
+				case valueStream <- fn():
+				}
+			}
+		}()
+		return valueStream
+	}
+	take := func(
+		done <-chan interface{},
+		valueStream <-chan interface{},
+		num int,
+	) <-chan interface{} {
+		takeStream := make(chan interface{})
+		go func() {
+			defer close(takeStream)
+			for i := 0; i < num; i++ {
+				select {
+				case <-done:
+					return
+				case takeStream <- <-valueStream:
+				}
+			}
+		}()
+		return takeStream
+	}
+	done := make(chan interface{})
+	defer close(done)
+
+	rand := func() interface{} { return rand.Int() }
+
+	for num := range take(done, repeatFn(done, rand), 10) {
+		fmt.Println(num)
+	}
+}