Implement iterator-returning Fugit::Cron#next

and `#prev`

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ## fugit 1.10.0 not yet released
 
+* Implement iterator-returning `Fugit::Cron#next` and `#prev`
+
 
 ## fugit 1.9.0 released 2023-10-24
 

lib/fugit/cron.rb

@@ -318,6 +318,33 @@ def previous_time(from=::EtOrbi::EoTime.now)
       t.time.translate(from.zone)
     end
 
+    # Used by Fugit::Cron#next and Fugit::Cron#prev
+    #
+    class CronIterator include ::Enumerable
+      attr_reader :cron, :start, :current, :direction
+      def initialize(cron, direction, start)
+        @cron = cron
+        @start = start
+        @current = start.dup
+        @direction = direction
+      end
+      def each
+        loop do
+          yield(@current = @cron.send(@direction, @current))
+        end
+      end
+    end
+
+    def next(from=::EtOrbi::EoTime.now)
+
+      CronIterator.new(self, :next_time, from)
+    end
+
+    def prev(from=::EtOrbi::EoTime.now)
+
+      CronIterator.new(self, :previous_time, from)
+    end
+
     # Mostly used as a #next_time sanity check.
     # Avoid for "business" use, it's slow.
     #

spec/cron_spec.rb

@@ -1631,6 +1631,55 @@ class Fugit::Cron::TimeCursor
       end
     end
   end
+
+  describe '#within' do
+  end
+
+  describe '#next' do
+
+    it 'returns an iterator' do
+
+      c = Fugit.parse_cron('0 12 * * mon#2')
+
+      in_zone 'UTC'  do
+
+        expect(
+          c.next
+            .take(5)
+            .map(&:to_s)
+        ).to eq([
+          '2024-03-11 12:00:00 Z',
+          '2024-04-08 12:00:00 Z',
+          '2024-05-13 12:00:00 Z',
+          '2024-06-10 12:00:00 Z',
+          '2024-07-08 12:00:00 Z'
+        ])
+      end
+    end
+  end
+
+  describe '#prev' do
+
+    it 'returns an iterator' do
+
+      c = Fugit.parse_cron('0 12 * * mon#2')
+
+      in_zone 'UTC'  do
+
+        expect(
+          c.prev
+            .take(5)
+            .map(&:to_s)
+        ).to eq([
+          '2024-02-12 12:00:00 Z',
+          '2024-01-08 12:00:00 Z',
+          '2023-12-11 12:00:00 Z',
+          '2023-11-13 12:00:00 Z',
+          '2023-10-09 12:00:00 Z'
+        ])
+      end
+    end
+  end
 end
 
 describe Fugit do