map filter reduce

helper/func.go

@@ -175,10 +175,27 @@ func ClearClosedTag(s []string) []string {
 	}
 }
 
-func SliceMap[T any, R any](arr []T, fun func(T) R) []R {
+func SliceMap[T, R any](arr []T, fn func(T) R) []R {
 	r := make([]R, 0, len(arr))
 	for _, t := range arr {
-		r = append(r, fun(t))
+		r = append(r, fn(t))
+	}
+	return r
+}
+
+func SliceFilter[T any](arr []T, fn func(T) bool) []T {
+	var r []T
+	for _, t := range arr {
+		if fn(t) {
+			r = append(r, t)
+		}
+	}
+	return r
+}
+
+func SliceReduce[T, R any](arr []T, fn func(T, R) R, r R) R {
+	for _, t := range arr {
+		r = fn(t, r)
 	}
 	return r
 }

helper/func_test.go

@@ -326,3 +326,58 @@ func Test_clearTag(t *testing.T) {
 		})
 	}
 }
+
+func TestSliceReduce(t *testing.T) {
+	type args struct {
+		arr []int
+		fn  func(int, int) int
+		r   int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "t1",
+			args: args{arr: RangeSlice(1, 10, 1), fn: func(i int, i2 int) int {
+				return i + i2
+			}},
+			want: 55,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := SliceReduce(tt.args.arr, tt.args.fn, tt.args.r); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("SliceReduce() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestSliceFilter(t *testing.T) {
+	type args struct {
+		arr []int
+		fn  func(int) bool
+	}
+	tests := []struct {
+		name string
+		args args
+		want []int
+	}{
+		{
+			name: "t1",
+			args: args{arr: RangeSlice(1, 10, 1), fn: func(i int) bool {
+				return i > 4
+			}},
+			want: RangeSlice(5, 10, 1),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := SliceFilter(tt.args.arr, tt.args.fn); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("SliceFilter() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}