Strict Matching

README.md

@@ -14,5 +14,32 @@ next_time = cron_parser.next(Time.now)
 
 # Last occurrence
 most_recent_time = cron_parser.last(Time.now)
+
+# next 5 occurences
+next_times = cron_parser.next(Time.now,5)
+
+# last 5 occurences
+previous_times = cron_parser.last(Time.now,5)
+```
+
+## Strict Matching AKA Friday the 13th matching
+
+From the crontab manpage:
+```
+If both fields are restricted (i.e., aren't '*'), the command will be run when either field matches the current time. For example, ``30 4 1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th of each month, plus every Friday.
 ```
 
+While this is the designed behavior, Some might not find it to be desireable or expected. If you want to match based on Day of Week AND Day of month, you can turn on strict matching with a parameter when you initialize.
+
+Let's take a look at the difference between the two modes. 
+
+```
+# Normal behavior
+CronParser.new('0 1 13 * 5', Time).next(Time.now, 4)
+=> [Fri 25 Mar 2016, Fri 01 Apr 2016, Fri 08 Apr 2016, Wed 13 Apr 2016]
+
+# Strict Matching
+CronParser.new('0 1 13 * 5', Time,true).next(Time.now, 4)
+=> [Fri 13 May 2016, Fri 13 Jan 2017, Fri 13 Oct 2017, Fri, 13 Apr 2018]
+
+```

lib/cron_parser.rb

@@ -15,7 +15,6 @@ def initialize(time,time_source = Time)
       @day = time.day
       @hour = time.hour
       @min = time.min
-
       @time_source = time_source
     end
 
@@ -51,8 +50,9 @@ def inspect
      "sat" => "6"
   }
 
-  def initialize(source,time_source = Time)
+  def initialize(source,time_source = Time, strict_match = false)
     @source = interpret_vixieisms(source)
+    set_strict_match(strict_match)
     @time_source = time_source
     validate_source
   end
@@ -80,7 +80,6 @@ def interpret_vixieisms(spec)
   # returns the next occurence after the given date
   def next(now = @time_source.now, num = 1)
     t = InternalTime.new(now, @time_source)
-
     unless time_specs[:month][0].include?(t.month)
       nudge_month(t)
       t.day = 0
@@ -91,7 +90,7 @@ def next(now = @time_source.now, num = 1)
       t.hour = -1
     end
 
-    unless time_specs[:hour][0].include?(t.hour)
+   unless time_specs[:hour][0].include?(t.hour)
       nudge_hour(t)
       t.min = -1
     end
@@ -184,19 +183,24 @@ def interpolate_weekdays_without_cache(year, month)
 
     # Careful, if both DOW and DOM fields are non-wildcard,
     # then we only need to match *one* for cron to run the job:
-    if not (mday_field == '*' and wday_field == '*')
-      valid_mday = [] if mday_field == '*'
-      valid_wday = [] if wday_field == '*'
+    unless strict_match?
+      unless (mday_field == '*' and wday_field == '*')
+        valid_mday = [] if mday_field == '*'
+        valid_wday = [] if wday_field == '*'
+      end
     end
     # Careful: crontabs may use either 0 or 7 for Sunday:
     valid_wday << 0 if valid_wday.include?(7)
 
     result = []
     while t.month == month
-      result << t.mday if valid_mday.include?(t.mday) || valid_wday.include?(t.wday)
+      if strict_match?
+        result << t.mday if (valid_mday.include?(t.mday) && valid_wday.include?(t.wday))
+      else
+        result << t.mday if (valid_mday.include?(t.mday) || valid_wday.include?(t.wday))
+      end
       t = t.succ
     end
-
     [Set.new(result), result]
   end
 
@@ -208,39 +212,46 @@ def nudge_month(t, dir = :next)
     spec = time_specs[:month][1]
     next_value = find_best_next(t.month, spec, dir)
     t.month = next_value || (dir == :next ? spec.first : spec.last)
+    if strict_match?
+      until date_valid?(t)
+        next_value = find_best_next(t.month, spec, dir)
+        t.month = next_value || (dir == :next ? spec.first : spec.last)
+        nudge_year(t, dir) if next_value.nil?
+        valid_days = interpolate_weekdays(t.year, t.month)[1]
+        t.day = dir == :next ? valid_days.first : valid_days.last
+      end
+    else
+      nudge_year(t, dir) if next_value.nil?
+      # we changed the month, so its likely that the date is incorrect now
+      valid_days = interpolate_weekdays(t.year, t.month)[1]
+      t.day = dir == :next ? valid_days.first : valid_days.last
+    end
 
-    nudge_year(t, dir) if next_value.nil?
-
-    # we changed the month, so its likely that the date is incorrect now
-    valid_days = interpolate_weekdays(t.year, t.month)[1]
-    t.day = dir == :next ? valid_days.first : valid_days.last
   end
 
   def date_valid?(t, dir = :next)
-    interpolate_weekdays(t.year, t.month)[0].include?(t.day)
+    weekdays = interpolate_weekdays(t.year, t.month)[0]
+    weekdays.include?(t.day)
   end
 
   def nudge_date(t, dir = :next, can_nudge_month = true)
     spec = interpolate_weekdays(t.year, t.month)[1]
     next_value = find_best_next(t.day, spec, dir)
     t.day = next_value || (dir == :next ? spec.first : spec.last)
-
     nudge_month(t, dir) if next_value.nil? && can_nudge_month
   end
 
   def nudge_hour(t, dir = :next)
     spec = time_specs[:hour][1]
     next_value = find_best_next(t.hour, spec, dir)
     t.hour = next_value || (dir == :next ? spec.first : spec.last)
-
     nudge_date(t, dir) if next_value.nil?
   end
 
   def nudge_minute(t, dir = :next)
     spec = time_specs[:minute][1]
     next_value = find_best_next(t.min, spec, dir)
     t.min = next_value || (dir == :next ? spec.first : spec.last)
-
     nudge_hour(t, dir) if next_value.nil?
   end
 
@@ -267,10 +278,8 @@ def substitute_parse_symbols(str)
 
   def stepped_range(rng, step = 1)
     len = rng.last - rng.first
-
     num = len.div(step)
     result = (0..num).map { |i| rng.first + step * i }
-
     result.pop if result[-1] == rng.last and rng.exclude_end?
     result
   end
@@ -295,4 +304,16 @@ def validate_source
       raise ArgumentError, 'not a valid cronline'
     end
   end
+
+  def strict_match?
+    @strict_match
+  end
+
+  def set_strict_match(strict_match = false)
+    @strict_match = false
+    if strict_match && [time_specs[:dom].last, time_specs[:dow].last].all?{|v| v != '*'}
+      @strict_match = true
+    end
+  end
+
 end