Slice: find v2 (#17)

* If slice len is zero then return false
* Convert find to generic form.
* If return T is nil then no items matched the predicate func

slice/slice.go

@@ -167,7 +167,7 @@ func Some(slice, function interface{}) bool {
 
 // Filter iterates over elements of slice, returning an slice of all elements `signature` returns truthy for.
 // The fn signature should be func(int, T) bool.
-func Filter [T any] (slice []T, fn func(index int, t T) bool) []T {
+func Filter[T any](slice []T, fn func(index int, t T) bool) []T {
 	res := make([]T, 0, 0)
 	for i, v := range slice {
 		if fn(i, v) {
@@ -227,30 +227,25 @@ func GroupBy(slice, function interface{}) (interface{}, interface{}) {
 
 // Find iterates over elements of slice, returning the first one that passes a truth test on function.
 // The function signature should be func(index int, value interface{}) bool .
-func Find(slice, function interface{}) (interface{}, bool) {
-	sv := sliceValue(slice)
-	fn := functionValue(function)
-
-	elemType := sv.Type().Elem()
-	if checkSliceCallbackFuncSignature(fn, elemType, reflect.ValueOf(true).Type()) {
-		panic("function param should be of type func(int, " + elemType.String() + ")" + reflect.ValueOf(true).Type().String())
+// If return T is nil then no items matched the predicate func
+func Find[T any](slice []T, fn func(index int, t T) bool) (*T, bool) {
+	if len(slice) == 0 {
+		return nil, false
 	}
 
 	index := -1
-	for i := 0; i < sv.Len(); i++ {
-		flag := fn.Call([]reflect.Value{reflect.ValueOf(i), sv.Index(i)})[0]
-		if flag.Bool() {
+	for i, v := range slice {
+		if fn(i, v) {
 			index = i
 			break
 		}
 	}
 
 	if index == -1 {
-		var none interface{}
-		return none, false
+		return nil, false
 	}
 
-	return sv.Index(index).Interface(), true
+	return &slice[index], true
 }
 
 // FlattenDeep flattens slice recursive
@@ -279,7 +274,7 @@ func flattenRecursive(value reflect.Value, result reflect.Value) reflect.Value {
 
 // ForEach iterates over elements of slice and invokes function for each element
 // The fn signature should be func(int, T ).
-func ForEach [T any] (slice []T, fn func(index int, t T)) {
+func ForEach[T any](slice []T, fn func(index int, t T)) {
 	for i, v := range slice {
 		fn(i, v)
 	}
@@ -287,7 +282,7 @@ func ForEach [T any] (slice []T, fn func(index int, t T)) {
 
 // Map creates an slice of values by running each element of `slice` thru `function`.
 // The fn signature should be func(int, T).
-func Map [T any, U any] (slice []T, fn func(index int, t T) U) []U {
+func Map[T any, U any](slice []T, fn func(index int, t T) U) []U {
 	res := make([]U, len(slice), cap(slice))
 	for i, v := range slice {
 		res[i] = fn(i, v)

slice/slice_test.go

@@ -220,7 +220,7 @@ func TestFind(t *testing.T) {
 		t.Fatal("found nothing")
 	}
 
-	if res != 2 {
+	if *res != 2 {
 		internal.LogFailedTestInfo(t, "Find", nums, 2, res)
 		t.FailNow()
 	}