#30. Fix step > 1 + readme

README.md

@@ -236,6 +236,7 @@ creates an int slice of min to max range
 ```go
 pgo.Range(3, 9) // []int{3, 4, 5, 6, 7, 8, 9}
 
-pgo.Range(-3, 7) // []int{-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7}
+// If a step value is given, it will be used as the increment between elements in the sequence.
+pgo.Range(-3, 7, 5) // []int{-3, 2, 7}
 ```
 See more examples in *_test.go files.

array.go

@@ -218,11 +218,24 @@ func ArrayIntersect(arrays ...interface{}) []interface{} {
 	return result
 }
 
-// Range creates an int slice of min to max range
-func Range(min, max int) []int {
+// Range creates int slice of min to max range
+// If a step value is given, it will be used as the increment between elements in the sequence.
+// step should be given as a positive number.
+// If not specified, step will default to 1.
+func Range(min, max int, step ...interface{}) []int {
 	var slice []int
 
-	for i := min; i <= max; i++ {
+	var argsLen = len(step)
+
+	var stepp = 1
+	if argsLen > 0 && step[0] != nil {
+		st, ok := step[0].(int)
+		if !ok || st > 1 {
+			stepp = st
+		}
+	}
+
+	for i := min; i <= max; i += stepp {
 		slice = append(slice, i)
 	}
 

array_test.go

@@ -287,6 +287,16 @@ var testRange = []struct {
 	{-3, 7, []int{-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7}},
 }
 
+var testRangeWithStep = []struct {
+	min    int
+	max    int
+	step   int
+	result []int
+}{
+	{3, 9, 2, []int{3, 5, 7, 9}},
+	{-3, 7, 5, []int{-3, 2, 7}},
+}
+
 func TestRange(t *testing.T) {
 	for _, object := range testRange {
 
@@ -297,4 +307,14 @@ func TestRange(t *testing.T) {
 			}
 		}
 	}
+
+	for _, object := range testRangeWithStep {
+
+		res := pgo.Range(object.min, object.max, object.step)
+		for k, v := range res {
+			if v != object.result[k] {
+				t.Fatalf("want %v, got %v", object.result[k], v)
+			}
+		}
+	}
 }