From d231d9f572013cb5ba84683cbc1d1c37e46aeed0 Mon Sep 17 00:00:00 2001
From: dudaodong <lanliddd.2007@163.com>
Date: Thu, 9 Feb 2023 17:53:26 +0800
Subject: [PATCH] feat: add DropRightWhile

---
 slice/slice.go              | 16 ++++++++++++++++
 slice/slice_example_test.go | 23 +++++++++++++++++++++++
 slice/slice_test.go         | 21 +++++++++++++++++++++
 3 files changed, 60 insertions(+)

diff --git a/slice/slice.go b/slice/slice.go
index 3f1e89e..04e712f 100644
--- a/slice/slice.go
+++ b/slice/slice.go
@@ -610,6 +610,22 @@ func DropWhile[T any](slice []T, predicate func(item T) bool) []T {
 	return append(result, slice[i:]...)
 }
 
+// DropRightWhile drop n elements from the end of a slice while predicate function returns true.
+// Play: todo
+func DropRightWhile[T any](slice []T, predicate func(item T) bool) []T {
+	i := len(slice) - 1
+
+	for ; i >= 0; i-- {
+		if !predicate(slice[i]) {
+			break
+		}
+	}
+
+	result := make([]T, 0, i+1)
+
+	return append(result, slice[:i+1]...)
+}
+
 // InsertAt insert the value or other slice into slice at index.
 // Play: https://go.dev/play/p/hMLNxPEGJVE
 func InsertAt[T any](slice []T, index int, value any) []T {
diff --git a/slice/slice_example_test.go b/slice/slice_example_test.go
index ce1584d..faae325 100644
--- a/slice/slice_example_test.go
+++ b/slice/slice_example_test.go
@@ -527,6 +527,29 @@ func ExampleDropWhile() {
 	// [1 2 3 4 5]
 }
 
+func ExampleDropRightWhile() {
+	numbers := []int{1, 2, 3, 4, 5}
+
+	result1 := DropRightWhile(numbers, func(n int) bool {
+		return n != 2
+	})
+	result2 := DropRightWhile(numbers, func(n int) bool {
+		return true
+	})
+	result3 := DropRightWhile(numbers, func(n int) bool {
+		return n == 0
+	})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// [1 2]
+	// []
+	// [1 2 3 4 5]
+}
+
 func ExampleInsertAt() {
 	result1 := InsertAt([]string{"a", "b", "c"}, 0, "1")
 	result2 := InsertAt([]string{"a", "b", "c"}, 1, "1")
diff --git a/slice/slice_test.go b/slice/slice_test.go
index 4307e53..33b1d11 100644
--- a/slice/slice_test.go
+++ b/slice/slice_test.go
@@ -427,6 +427,27 @@ func TestDropWhile(t *testing.T) {
 	assert.Equal([]int{1, 2, 3, 4, 5}, r3)
 }
 
+func TestDropRightWhile(t *testing.T) {
+	assert := internal.NewAssert(t, "TestDropRightWhile")
+
+	numbers := []int{1, 2, 3, 4, 5}
+
+	r1 := DropRightWhile(numbers, func(n int) bool {
+		return n != 2
+	})
+	assert.Equal([]int{1, 2}, r1)
+
+	r2 := DropRightWhile(numbers, func(n int) bool {
+		return true
+	})
+	assert.Equal([]int{}, r2)
+
+	r3 := DropRightWhile(numbers, func(n int) bool {
+		return n == 0
+	})
+	assert.Equal([]int{1, 2, 3, 4, 5}, r3)
+}
+
 func TestInsertAt(t *testing.T) {
 	assert := internal.NewAssert(t, "TestInsertAt")