From b8563ed6467fa8070fc0153a335ae7eec2153fb0 Mon Sep 17 00:00:00 2001
From: dudaodong <dudaodong@gmail.com>
Date: Sat, 15 Oct 2022 12:29:47 +0800
Subject: [PATCH] feat: add Pipeline function

---
 function/function.go      | 12 ++++++++++++
 function/function_test.go | 18 ++++++++++++++++++
 function/watcher_test.go  |  2 ++
 3 files changed, 32 insertions(+)

diff --git a/function/function.go b/function/function.go
index 67976c0..c6356c8 100644
--- a/function/function.go
+++ b/function/function.go
@@ -113,3 +113,15 @@ func Schedule(d time.Duration, fn any, args ...any) chan bool {
 
 	return quit
 }
+
+// Pipeline takes a list of functions and returns a function whose param will be passed into
+// the functions one by one.
+func Pipeline[T any](funcs ...func(T) T) func(T) T {
+	return func(arg T) (result T) {
+		result = arg
+		for _, fn := range funcs {
+			result = fn(result)
+		}
+		return
+	}
+}
diff --git a/function/function_test.go b/function/function_test.go
index 7f12599..1f5b7e1 100644
--- a/function/function_test.go
+++ b/function/function_test.go
@@ -134,3 +134,21 @@ func TestSchedule(t *testing.T) {
 	// expected := []string{"*", "*", "*", "*", "*"}
 	// assert.Equal(expected, res)
 }
+
+func TestPipeline(t *testing.T) {
+	assert := internal.NewAssert(t, "TestPipeline")
+
+	addOne := func(x int) int {
+		return x + 1
+	}
+	double := func(x int) int {
+		return 2 * x
+	}
+	square := func(x int) int {
+		return x * x
+	}
+
+	f := Pipeline(addOne, double, square)
+
+	assert.Equal(36, f(2))
+}
diff --git a/function/watcher_test.go b/function/watcher_test.go
index a0ab1d8..fb7c981 100644
--- a/function/watcher_test.go
+++ b/function/watcher_test.go
@@ -1,6 +1,7 @@
 package function
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
@@ -34,4 +35,5 @@ func longRunningTask() {
 	for i := 0; i < 10000000; i++ {
 		slice = append(slice, int64(i))
 	}
+	fmt.Println(slice)
 }