doc: add doc for sort function

docs/slice.md

@@ -63,6 +63,10 @@ import (
 -   [ReplaceAll](#ReplaceAll)
 -   [Repeat](#Repeat)
 -   [Shuffle](#Shuffle)
+-   [IsAscending](#IsAscending)
+-   [IsDescending](#IsDescending)
+-   [IsSorted](#IsSorted)
+-   [IsSortedByKey](#IsSortedByKey)
 -   [Sort](#Sort)
 -   [SortBy](#SortBy)
 -   [SortByField<sup>deprecated</sup>](#SortByField)
@@ -1470,6 +1474,148 @@ func main() {
 }
 ```
 
+### <span id="IsAscending">IsAscending</span>
+
+<p>Checks if a slice is ascending order.</p>
+
+<b>Signature:</b>
+
+```go
+func IsAscending[T constraints.Ordered](slice []T) bool
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsAscending([]int{1, 2, 3, 4, 5})
+	result2 := slice.IsAscending([]int{5, 4, 3, 2, 1})
+	result3 := slice.IsAscending([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// false
+	// false
+}
+```
+
+### <span id="IsDescending">IsDescending</span>
+
+<p>Checks if a slice is descending order.</p>
+
+<b>Signature:</b>
+
+```go
+func IsDescending[T constraints.Ordered](slice []T) bool
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsDescending([]int{5, 4, 3, 2, 1})
+	result2 := slice.IsDescending([]int{1, 2, 3, 4, 5})
+	result3 := slice.IsDescending([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// false
+	// false
+}
+```
+
+### <span id="IsSorted">IsSorted</span>
+
+<p>Checks if a slice is sorted (ascending or descending).</p>
+
+<b>Signature:</b>
+
+```go
+func IsSorted[T constraints.Ordered](slice []T) bool
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsSorted([]int{5, 4, 3, 2, 1})
+	result2 := slice.IsSorted([]int{1, 2, 3, 4, 5})
+	result3 := slice.IsSorted([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// true
+	// false
+}
+```
+
+### <span id="IsSortedByKey">IsSortedByKey</span>
+
+<p>Checks if a slice is sorted by iteratee function.</p>
+
+<b>Signature:</b>
+
+```go
+func IsSortedByKey[T any, K constraints.Ordered](slice []T, iteratee func(item T) K) bool
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsSortedByKey([]string{"a", "ab", "abc"}, func(s string) int {
+		return len(s)
+	})
+	result2 := slice.IsSortedByKey([]string{"abc", "ab", "a"}, func(s string) int {
+		return len(s)
+	})
+	result3 := slice.IsSortedByKey([]string{"abc", "a", "ab"}, func(s string) int {
+		return len(s)
+	})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// true
+	// false
+}
+```
+
 ### <span id="Sort">Sort</span>
 
 <p>Sorts a slice of any ordered type(number or string), use quick sort algrithm. Default sort order is ascending (asc), if want descending order, set param `sortOrder` to `desc`. Ordered type: number(all ints uints floats) or string.

docs/slice_zh-CN.md

@@ -63,6 +63,10 @@ import (
 -   [ReplaceAll](#ReplaceAll)
 -   [Repeat](#Repeat)
 -   [Shuffle](#Shuffle)
+-   [IsAscending](#IsAscending)
+-   [IsDescending](#IsDescending)
+-   [IsSorted](#IsSorted)
+-   [IsSortedByKey](#IsSortedByKey)
 -   [Sort](#Sort)
 -   [SortBy](#SortBy)
 -   [SortByField<sup>deprecated</sup>](#SortByField)
@@ -1472,6 +1476,148 @@ func main() {
 }
 ```
 
+### <span id="IsAscending">IsAscending</span>
+
+<p>检查切片元素是否按升序排列。</p>
+
+<b>函数签名:</b>
+
+```go
+func IsAscending[T constraints.Ordered](slice []T) bool
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsAscending([]int{1, 2, 3, 4, 5})
+	result2 := slice.IsAscending([]int{5, 4, 3, 2, 1})
+	result3 := slice.IsAscending([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// false
+	// false
+}
+```
+
+### <span id="IsDescending">IsDescending</span>
+
+<p>检查切片元素是否按降序排列。</p>
+
+<b>函数签名:</b>
+
+```go
+func IsDescending[T constraints.Ordered](slice []T) bool
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsDescending([]int{5, 4, 3, 2, 1})
+	result2 := slice.IsDescending([]int{1, 2, 3, 4, 5})
+	result3 := slice.IsDescending([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// false
+	// false
+}
+```
+
+### <span id="IsSorted">IsSorted</span>
+
+<p>检查切片元素是否是有序的（升序或降序）。</p>
+
+<b>函数签名:</b>
+
+```go
+func IsSorted[T constraints.Ordered](slice []T) bool
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsSorted([]int{5, 4, 3, 2, 1})
+	result2 := slice.IsSorted([]int{1, 2, 3, 4, 5})
+	result3 := slice.IsSorted([]int{2, 1, 3, 4, 5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// true
+	// false
+}
+```
+
+### <span id="IsSortedByKey">IsSortedByKey</span>
+
+<p>通过iteratee函数，检查切片元素是否是有序的。</p>
+
+<b>函数签名:</b>
+
+```go
+func IsSortedByKey[T any, K constraints.Ordered](slice []T, iteratee func(item T) K) bool
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+    result1 := slice.IsSortedByKey([]string{"a", "ab", "abc"}, func(s string) int {
+		return len(s)
+	})
+	result2 := slice.IsSortedByKey([]string{"abc", "ab", "a"}, func(s string) int {
+		return len(s)
+	})
+	result3 := slice.IsSortedByKey([]string{"abc", "a", "ab"}, func(s string) int {
+		return len(s)
+	})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+
+	// Output:
+	// true
+	// true
+	// false
+}
+```
+
 ### <span id="Sort">Sort</span>
 
 <p>对任何有序类型（数字或字符串）的切片进行排序，使用快速排序算法。 默认排序顺序为升序 (asc)，如果需要降序，请将参数 `sortOrder` 设置为 `desc`。 Ordered类型：数字（所有整数浮点数）或字符串。</p>