🐛 Fixing a bug. about pointer package function (#230)

update:
1. UnwarpOr
2. UnwarpOrDefault
3. ExtractPointer

add:
1. UnwrapOr
2. IsNil

pointer/pointer.go

@@ -11,17 +11,24 @@ import (
 // Of returns a pointer to the value `v`.
 // Play: https://go.dev/play/p/HFd70x4DrMj
 func Of[T any](v T) *T {
+	if IsNil(v) {
+		return nil
+	}
 	return &v
 }
 
 // Unwrap returns the value from the pointer.
-// Play: https://go.dev/play/p/cgeu3g7cjWb
+//
+//	Play: https://go.dev/play/p/cgeu3g7cjWb
+//	Deprecated: Please use UnwrapOr
 func Unwrap[T any](p *T) T {
 	return *p
 }
 
 // UnwarpOr returns the value from the pointer or fallback if the pointer is nil.
-// Play: https://go.dev/play/p/mmNaLC38W8C
+//
+//	Play: https://go.dev/play/p/mmNaLC38W8C
+//	Deprecated: Please use UnwrapOr
 func UnwarpOr[T any](p *T, fallback T) T {
 	if p == nil {
 		return fallback
@@ -30,7 +37,9 @@ func UnwarpOr[T any](p *T, fallback T) T {
 }
 
 // UnwarpOrDefault returns the value from the pointer or the default value if the pointer is nil.
-// Play: https://go.dev/play/p/ZnGIHf8_o4E
+//
+//	Play: https://go.dev/play/p/ZnGIHf8_o4E
+//	Deprecated: Please use UnwrapOr
 func UnwarpOrDefault[T any](p *T) T {
 	var v T
 
@@ -40,9 +49,24 @@ func UnwarpOrDefault[T any](p *T) T {
 	return *p
 }
 
+// UnwrapOr returns the value from the pointer or fallback if the pointer is nil.
+func UnwrapOr[T any](p *T, fallback ...T) T {
+	if !IsNil(p) {
+		return *p
+	}
+	if len(fallback) > 0 {
+		return fallback[0]
+	}
+	var t T
+	return t
+}
+
 // ExtractPointer returns the underlying value by the given interface type
 // Play: https://go.dev/play/p/D7HFjeWU2ZP
 func ExtractPointer(value any) any {
+	if IsNil(value) {
+		return value
+	}
 	t := reflect.TypeOf(value)
 	v := reflect.ValueOf(value)
 
@@ -56,3 +80,8 @@ func ExtractPointer(value any) any {
 
 	return nil
 }
+
+// IsNil returns true if the given interface is nil or the underlying value is nil.
+func IsNil(i interface{}) bool {
+	return i == nil || (reflect.ValueOf(i).Kind() == reflect.Ptr && reflect.ValueOf(i).IsNil())
+}

pointer/pointer_examples_test.go

@@ -90,3 +90,61 @@ func ExampleExtractPointer() {
 	// Output:
 	// 1
 }
+
+func ExampleIsNil() {
+	a := 1
+	b := &a
+	c := &b
+	d := &c
+	e := &d
+	var f *int
+
+	result1 := IsNil(a)
+	result2 := IsNil(b)
+	result3 := IsNil(c)
+	result4 := IsNil(d)
+	result5 := IsNil(e)
+	result6 := IsNil(f)
+	result7 := IsNil(nil)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+	fmt.Println(result4)
+	fmt.Println(result5)
+	fmt.Println(result6)
+	fmt.Println(result7)
+
+	// Output:
+	// false
+	// false
+	// false
+	// false
+	// false
+	// true
+	// true
+}
+
+func ExampleUnwrapOr() {
+	a := 123
+	b := "abc"
+
+	var c *int
+	var d *string
+
+	result1 := UnwrapOr(&a, 456)
+	result2 := UnwrapOr(&b, "efg")
+	result3 := UnwrapOr(c, 456)
+	result4 := UnwrapOr(d, "def")
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+	fmt.Println(result4)
+
+	// Output:
+	// 123
+	// abc
+	// 456
+	// def
+}