first working version of new .tagged method. Pending: check nils, reset vs cancel, scope caching

README.textile

@@ -9,6 +9,7 @@ h1. Examples of use
 * @cron.cancel(id)@ will stop a timed action from happening, and will interrupt the periodical execution of a periodic action.
 * @cron.reset()@ removes all timed and periodic actions, and resets the time passed back to 0.
 * @cron.update(dt)@ is needed to be executed on the main program loop. @dt@ is the amount of time that has passed since the last iteration. When @cron.update@ is executed, cron will check the list of pending actions and execute them if needed.
+* @cron.tagged(tag1, tag2, tag3 ...)@ filters other cron methods (@cron.after@, @cron.every@, @cron.update@ & @cron.cancel@ but not @cron.reset@) so that they create clocks with specific tags/ act on clocks with specific tags.
 
 <pre>
 local cron = require 'cron'
@@ -35,6 +36,20 @@ cron.cancel(id) -- stops the execution the element defined by id. Works with per
 cron.reset() -- stops all the current actions, both timed ones and periodical ones.
 </pre>
 
+Some tag examples:
+<pre>
+  -- This has the same effect of cron.after(2, showMenu), except that the
+  -- time entry is tagged with the tags 'main-menu' and 'menu'
+  cron.tagged('main-menu', 'menu').after(2, showMenu)
+
+  -- This updates the time entries tagged with the tag 'menu', but not the rest
+  cron.tagged('menu').update(2)
+
+  -- cron.cancel does not admit filtering via tags, but it admits tags as params
+  -- the previous call is equivalent to this one:
+  cron.tagged('main-menu').cancel()
+</pre>
+
 
 h1. Gotchas / Warnings
 

cron.lua

@@ -13,7 +13,8 @@
 
 -- Private functions
 
-local entries = {}
+local entries, tagGroups -- initialized in cron.reset
+local cron = {}
 
 local function isCallable(callback)
   local tc = type(callback)
@@ -46,7 +47,7 @@ local function updateTimedEntry(self, dt) -- returns true if expired
   self.running = self.running + dt
   if self.running >= self.time then
     self.callback(unpack(self.args))
-    entries[self] = nil
+    cron.cancel(self)
   end
 end
 
@@ -59,16 +60,62 @@ local function updatePeriodicEntry(self, dt)
   end
 end
 
--- Public functions
-
-local cron = {}
-
-function cron.reset()
-  entries = {}
+local function addTags(...)
+  local tags = {...}
+  local len  = #tags
+  for i=1, len do
+    local tag = tags[i]
+    taggedEntries[tag] = taggedEntries[tag] or setmetatable({}, {__mode = 'k'})
+  end
+  return tags, len
 end
 
+local function registerEntry(scope, entry)
+  for i=1, scope.len do
+    taggedEntries[scope.tags[i]][entry] = entry
+  end
+  entry.tags = scope.tags
+  return entry
+end
+
+function tagged_update(scope, dt)
+  for i=1, scope.len do
+    for _,entry in pairs(taggedEntries[scope.tags[i]]) do
+      entry:update(dt)
+    end
+  end
+end
+
+function tagged_cancel(scope)
+  for i=1, scope.len do
+    local tag = scope.tags[i]
+    for _,entry in pairs(taggedEntries[tag]) do
+      cron.cancel(entry)
+    end
+    taggedEntries[tag] = nil
+  end
+end
+
+local function newTaggedScope(tags, len)
+  local scope = { tags = tags, len = len }
+
+  scope.after  = function(...) return registerEntry(scope, cron.after(...)) end
+  scope.every  = function(...) return registerEntry(scope, cron.every(...)) end
+  scope.update = function(dt) tagged_update(scope, dt) end
+  scope.cancel = function(dt) tagged_cancel(scope) end
+
+  return scope
+end
+
+-- Public functions
+
 function cron.cancel(id)
   entries[id] = nil
+  if id.tags then
+    for i=1, #id.tags do
+      taggedEntries[id.tags[i]][id] = nil
+    end
+  end
 end
 
 function cron.after(time, callback, ...)
@@ -87,5 +134,19 @@ function cron.update(dt)
   for _, entry in pairs(entries) do entry:update(dt) end
 end
 
+function cron.tagged(...)
+  return newTaggedScope(addTags(...))
+end
+
+function cron.reset()
+  entries = {}
+  taggedEntries = setmetatable({}, {__mode='k'})
+end
+
+-- tagged functions
+
+
+cron.reset()
+
 return cron
 

spec/cron_spec.lua

@@ -128,4 +128,31 @@ describe( 'cron', function()
       assert_equal(counter, 1)
     end)
   end)
+
+  describe('.tagged', function()
+    before(function()
+      cron.tagged('hello').every(5, count) -- A
+      cron.tagged('hello').after(2, count) -- B
+      cron.every(1, count)                 -- C
+    end)
+
+    it('filters update', function()
+      cron.tagged('hello').update(5)
+      assert_equal(counter, 2)  -- A + B, but not C
+    end)
+
+    it('filters cancel', function()
+      cron.tagged('hello', 'girl').every(5, count) -- D
+
+      cron.tagged('hello').update(5) -- A + B + D - C
+      assert_equal(counter, 3)
+
+      cron.tagged('girl').cancel()
+      cron.tagged('hello').update(5) -- A + B - C
+      assert_equal(counter, 4)
+
+      cron.tagged('girl').update(5) -- nothing (D is cancelled)
+      assert_equal(counter, 4)
+    end)
+  end)
 end)