完善range

helper/func.go

@@ -30,10 +30,17 @@ func StructColumn[T any, M any](arr []M, field string) (r []T) {
 }
 
 func RangeSlice[T ~int | ~uint | ~int64 | ~int8 | ~int16 | ~int32 | ~uint64](start, end, step T) []T {
-	r := make([]T, 0, int((end-start+1)/step+1))
+	l := int((end-start+1)/step + 1)
-	for i := start; i <= end; {
+	if l < 0 {
+		l = 0 - l
+	}
+	r := make([]T, 0, l)
+	for i := start; ; {
 		r = append(r, i)
 		i = i + step
+		if (step > 0 && i > end) || (step < 0 && i < end) {
+			break
+		}
 	}
 	return r
 }
@@ -199,3 +206,11 @@ func SliceReduce[T, R any](arr []T, fn func(T, R) R, r R) R {
 	}
 	return r
 }
+
+func SliceReverse[T any](arr []T) []T {
+	var r []T
+	for i := len(arr); i > 0; i-- {
+		r = append(r, arr[i-1])
+	}
+	return r
+}

helper/func_test.go

@@ -112,6 +112,15 @@ func TestRangeSlice(t *testing.T) {
 			},
 			want: []int{1, 4, 7, 10},
 		},
+		{
+			name: "t4",
+			args: args{
+				start: 0,
+				end:   -5,
+				step:  -1,
+			},
+			want: []int{0, -1, -2, -3, -4, -5},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -411,3 +420,27 @@ func TestSliceMap(t *testing.T) {
 		})
 	}
 }
+
+func TestSliceReverse(t *testing.T) {
+	type args struct {
+		arr []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want []int
+	}{
+		{
+			name: "t1",
+			args: args{arr: RangeSlice(1, 10, 1)},
+			want: RangeSlice(10, 1, -1),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := SliceReverse(tt.args.arr); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("SliceReverse() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}