add interval notation e.g */3

pattern.go

@@ -2,6 +2,7 @@ package cron
 
 import(
  "fmt"
+ "math"
  "regexp"
  "strconv"
  "strings"
@@ -38,6 +39,16 @@ func (r *Range) Matches(timePart int) bool {
  return timePart >= r.min && timePart <= r.max
 }
 
+type Interval struct {
+ field string
+ numerator FieldMatcher
+ denominator int
+}
+
+func (interval *Interval) Matches(timePart int) bool {
+ return interval.numerator.Matches(timePart) && math.Mod(float64(timePart), float64(interval.denominator)) == 0
+}
+
 type CronSchedule struct {
  minutes FieldMatcher
  hours FieldMatcher
@@ -56,6 +67,14 @@ func (schedule CronSchedule) ShouldRun(t time.Time) bool {
 
 }
 
+func safeAtoi(str string) int {
+ number, err := strconv.Atoi(str)
+ if err != nil {
+ panic(fmt.Sprintf("regexp matched integer, but couldn't convert %q to int", str))
+ }
+ return number
+}
+
 func parseField(field string) FieldMatcher {
  constantRegexp, err := regexp.Compile(`\A\d+\z`)
  if err != nil {
@@ -65,26 +84,29 @@ func parseField(field string) FieldMatcher {
  if err != nil {
  panic("invalid hardcoded regexp!")
  }
+ intervalRegexp, err := regexp.Compile(`\A.*/\d+\z`)
+ if err != nil {
+ panic("invalid hardcoded regexp!")
+ }
 
  if "*" == field {
  return &Wildcard{field}
  } else if constantRegexp.MatchString(field) {
- number, err := strconv.Atoi(field)
- if err != nil {
- panic(fmt.Sprintf("regexp matched integer, but couldn't convert %q to int", field))
- }
- return &Constant{field, number}
+ return &Constant{field, safeAtoi(field)}
  } else if rangeRegexp.MatchString(field) {
  rangeParts := strings.Split(field, "-")
- min, err := strconv.Atoi(rangeParts[0])
- if err != nil {
- panic(fmt.Sprintf("regexp matched integer, but couldn't convert %q to int", rangeParts[0]))
+ return &Range{
+ field: field,
+ min: safeAtoi(rangeParts[0]),
+ max: safeAtoi(rangeParts[1]),
  }
- max, err := strconv.Atoi(rangeParts[1])
- if err != nil {
- panic(fmt.Sprintf("regexp matched integer, but couldn't convert %q to int", rangeParts[1]))
+ } else if intervalRegexp.MatchString(field) {
+ intervalParts := strings.Split(field, "/")
+ return &Interval{
+ field: field,
+ numerator: parseField(intervalParts[0]),
+ denominator: safeAtoi(intervalParts[1]),
  }
- return &Range{field, min, max}
  }
  return nil
 }

pattern_test.go

@@ -44,3 +44,19 @@ func TestRanges(t *testing.T) {
  {time.Date(2016, time.January, 5, 10, 8, 0, 0, time.UTC), true},
  })
 }
+
+func TestIntervals(t *testing.T) {
+ IsScheduled(t, "*/3 * * * * *", []TimeTestCase{
+ {time.Date(2016, time.January, 5, 10, 15, 0, 0, time.UTC), true},
+ {time.Date(2016, time.January, 5, 10, 5, 0, 0, time.UTC), false},
+ {time.Date(2016, time.January, 5, 10, 4, 0, 0, time.UTC), false},
+ {time.Date(2016, time.January, 5, 10, 33, 0, 0, time.UTC), true},
+ })
+
+ IsScheduled(t, "1-30/3 * * * * *", []TimeTestCase{
+ {time.Date(2016, time.January, 5, 10, 15, 0, 0, time.UTC), true},
+ {time.Date(2016, time.January, 5, 10, 5, 0, 0, time.UTC), false},
+ {time.Date(2016, time.January, 5, 10, 4, 0, 0, time.UTC), false},
+ {time.Date(2016, time.January, 5, 10, 33, 0, 0, time.UTC), false},
+ })
+}