From 1616d3d1be54a91ab8d414f578c872828bfedf94 Mon Sep 17 00:00:00 2001
From: will <3051227558@qq.com>
Date: Thu, 18 May 2023 10:17:15 +0800
Subject: [PATCH] feat:addFindLast for stream (#95)

Co-authored-by: sunyaoyao <sunyaoyao@kezaihui.com>
---
 stream/stream.go              | 12 ++++++++++++
 stream/stream_example_test.go | 13 +++++++++++++
 stream/stream_test.go         | 18 ++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/stream/stream.go b/stream/stream.go
index 23734a3..cc6b471 100644
--- a/stream/stream.go
+++ b/stream/stream.go
@@ -295,6 +295,18 @@ func (s stream[T]) FindFirst() (T, bool) {
 	return s.source[0], true
 }
 
+// FindLast returns the last element of this stream and true, or zero value and false if the stream is empty.
+// Play: https://go.dev/play/p/9xEf0-6C1e3
+func (s stream[T]) FindLast() (T, bool) {
+	var result T
+
+	if s.source == nil || len(s.source) == 0 {
+		return result, false
+	}
+
+	return s.source[len(s.source)-1], true
+}
+
 // Reverse returns a stream whose elements are reverse order of given stream.
 // Play: https://go.dev/play/p/A8_zkJnLHm4
 func (s stream[T]) Reverse() stream[T] {
diff --git a/stream/stream_example_test.go b/stream/stream_example_test.go
index 4842071..b854dfd 100644
--- a/stream/stream_example_test.go
+++ b/stream/stream_example_test.go
@@ -290,6 +290,19 @@ func ExampleStream_FindFirst() {
 	// true
 }
 
+func ExampleStream_FindLast() {
+	original := FromSlice([]int{3, 2, 1})
+
+	result, ok := original.FindLast()
+
+	fmt.Println(result)
+	fmt.Println(ok)
+
+	// Output:
+	// 1
+	// true
+}
+
 func ExampleStream_Reverse() {
 	original := FromSlice([]int{1, 2, 3})
 
diff --git a/stream/stream_test.go b/stream/stream_test.go
index 6523cce..b749f5d 100644
--- a/stream/stream_test.go
+++ b/stream/stream_test.go
@@ -273,6 +273,24 @@ func TestStream_FindFirst(t *testing.T) {
 	assert.Equal(true, ok)
 }
 
+func TestStream_FindLast(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_FindLast")
+
+	stream := FromSlice([]int{3, 2, 1})
+
+	result, ok := stream.FindLast()
+
+	assert.Equal(1, result)
+	assert.Equal(true, ok)
+
+	stream2 := FromSlice([]int{})
+
+	result, ok = stream2.FindLast()
+
+	assert.Equal(0, result)
+	assert.Equal(false, ok)
+}
+
 func TestStream_Reverse(t *testing.T) {
 	assert := internal.NewAssert(t, "TestStream_Reverse")