doc: add doc for Pipeline function

docs/function.md

@@ -29,6 +29,8 @@ import (
 -   [Compose](#Compose)
 -   [Debounced](#Debounced)
 -   [Delay](#Delay)
+-   [Pipeline](#Pipeline)
+-   [Schedule](#Schedule)
 -   [Watcher](#Watcher)
 
 <div STYLE="page-break-after: always;"></div>
@@ -298,6 +300,49 @@ func main() {
 }
 ```
 
+### <span id="Pipeline">Pipeline</span>
+
+<p>Pipeline takes a list of functions and returns a function whose param will be passed into
+the functions one by one.</p>
+
+<b>Signature:</b>
+
+```go
+func Pipeline(funcs ...func(interface{}) interface{}) func(interface{}) interface{}
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/function"
+)
+
+func main() {
+    addOne := func(x interface{}) interface{} {
+		return x.(int) + 1
+	}
+	double := func(x interface{}) interface{} {
+		return 2 * x.(int)
+	}
+	square := func(x interface{}) interface{} {
+		return x.(int) * x.(int)
+	}
+
+	f := function.Pipeline(addOne, double, square)
+
+    result := fn(2)
+
+    fmt.Println(result)
+
+    // Output:
+    // 36
+}
+```
+
 ### <span id="Watcher">Watcher</span>
 
 <p>Watcher is used for record code excution time. can start/stop/reset the watch timer. get the elapsed time of function execution.</p>

docs/function_zh-CN.md

@@ -29,6 +29,8 @@ import (
 -   [Compose](#Compose)
 -   [Debounced](#Debounced)
 -   [Delay](#Delay)
+-   [Pipeline](#Pipeline)
+-   [Schedule](#Schedule)
 -   [Watcher](#Watcher)
 
 <div STYLE="page-break-after: always;"></div>
@@ -298,6 +300,48 @@ func main() {
 }
 ```
 
+### <span id="Pipeline">Pipeline</span>
+
+<p>管道执行多个函数</p>
+
+<b>函数签名:</b>
+
+```go
+func Pipeline(funcs ...func(interface{}) interface{}) func(interface{}) interface{}
+```
+
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/function"
+)
+
+func main() {
+    addOne := func(x interface{}) interface{} {
+		return x.(int) + 1
+	}
+	double := func(x interface{}) interface{} {
+		return 2 * x.(int)
+	}
+	square := func(x interface{}) interface{} {
+		return x.(int) * x.(int)
+	}
+
+	f := function.Pipeline(addOne, double, square)
+
+    result := fn(2)
+
+    fmt.Println(result)
+
+    // Output:
+    // 36
+}
+```
+
 ### <span id="Watcher">Watcher</span>
 
 <p>Watcher 用于记录代码执行时间。可以启动/停止/重置手表定时器。获取函数执行的时间。 </p>

function/function.go

@@ -113,3 +113,15 @@ func Schedule(d time.Duration, fn interface{}, args ...interface{}) 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(funcs ...func(interface{}) interface{}) func(interface{}) interface{} {
+	return func(arg interface{}) (result interface{}) {
+		result = arg
+		for _, fn := range funcs {
+			result = fn(result)
+		}
+		return
+	}
+}

function/function_test.go

@@ -130,3 +130,21 @@ func TestSchedule(t *testing.T) {
 	expected := []string{"*", "*", "*", "*", "*"}
 	assert.Equal(expected, res)
 }
+
+func TestPipeline(t *testing.T) {
+	assert := internal.NewAssert(t, "TestPipeline")
+
+	addOne := func(x interface{}) interface{} {
+		return x.(int) + 1
+	}
+	double := func(x interface{}) interface{} {
+		return 2 * x.(int)
+	}
+	square := func(x interface{}) interface{} {
+		return x.(int) * x.(int)
+	}
+
+	f := Pipeline(addOne, double, square)
+
+	assert.Equal(36, f(2))
+}