Make sure that callbacks aren't invoked more than once

If the screen had a transition the delay caused the screen to render in its initial position for one frame before the transition was applied

README_API.md

@@ -33,6 +33,13 @@ Hide a screen that has been shown using the `no_stack` option. If used on a scre
 * `success` (boolean) - True if the process of hiding the screen was started successfully.
 
 
+## monarch.clear([callback])
+Clear the stack of screens completely. Any visible screen will be hidden by navigating back out from them. This operation will be added to the queue if Monarch is busy.
+
+**PARAMETERS**
+* `callback` (function) - Optional function to call when the stack has been cleared.
+
+
 ## monarch.back([data], [callback])
 Go back to a previous Monarch screen. This operation will be added to the queue if Monarch is busy.
 

game.project

@@ -1,7 +1,7 @@
 [project]
 title = Monarch
 version = 0.9
-dependencies = https://github.com/britzl/deftest/archive/2.7.0.zip
+dependencies#0 = https://github.com/britzl/deftest/archive/2.7.0.zip
 
 [bootstrap]
 main_collection = /example/advanced/advanced.collectionc

monarch/monarch.lua

@@ -1,4 +1,5 @@
 local callback_tracker = require "monarch.utils.callback_tracker"
+local async = require "monarch.utils.async"
 
 local M = {}
 
@@ -49,7 +50,7 @@ local transition_listeners = {}
 -- monarch is considered busy while there are active transitions
 local active_transition_count = 0
 
-local function log(...) end 
+local function log(...) end
 
 function M.debug()
 	log = print
@@ -604,9 +605,6 @@ local function show_in(screen, previous_screen, reload, add_to_stack, wait_for_t
 			notify_transition_listeners(M.SCREEN_TRANSITION_FAILED, { screen = screen.id })
 			return
 		end
-		-- wait until screen has had a chance to render
-		cowait(0)
-		cowait(0)
 		reset_timestep(screen)
 		transition(screen, M.TRANSITION.SHOW_IN, { previous_screen = previous_screen and previous_screen.id }, wait_for_transition)
 		screen.visible = true
@@ -631,9 +629,6 @@ local function back_in(screen, previous_screen, wait_for_transition, cb)
 			notify_transition_listeners(M.SCREEN_TRANSITION_FAILED, { screen = screen.id })
 			return
 		end
-		-- wait until screen has had a chance to render
-		cowait(0)
-		cowait(0)
 		reset_timestep(screen)
 		if previous_screen and not previous_screen.popup then
 			transition(screen, M.TRANSITION.BACK_IN, { previous_screen = previous_screen.id }, wait_for_transition)
@@ -750,8 +745,9 @@ function M.show(id, options, data, cb)
 						pop = pop - 1
 					end
 					stack[#stack] = nil
-					show_out(top, screen, WAIT_FOR_TRANSITION, callbacks.track())
-					callbacks.yield_until_done()
+					async(function(await, resume)
+						await(show_out, top, screen, WAIT_FOR_TRANSITION, resume)
+					end)
 					top = stack[#stack]
 				end
 
@@ -790,8 +786,9 @@ function M.show(id, options, data, cb)
 			local same_screen = top and top.id == screen.id
 			if same_screen or (options and options.sequential) then
 				if top then
-					show_out(top, screen, WAIT_FOR_TRANSITION, callbacks.track())
-					callbacks.yield_until_done()
+					async(function(await, resume)
+						await(show_out, top, screen, WAIT_FOR_TRANSITION, resume)
+					end)
 				end
 				show_in(screen, top, options and options.reload, add_to_stack, WAIT_FOR_TRANSITION, callbacks.track())
 			else
@@ -832,7 +829,7 @@ end
 
 -- Hide a screen. The screen must either be at the top of the stack or
 -- visible but not added to the stack (through the no_stack option)
--- @param id (string|hash) - Id of the screen to show
+-- @param id (string|hash) - Id of the screen to .hide
 -- @param cb (function) - Optional callback to invoke when the screen is hidden
 -- @return true if successfully hiding, false if busy or for some other reason unable to hide the screen
 function M.hide(id, cb)
@@ -869,6 +866,34 @@ function M.hide(id, cb)
 end
 
 
+
+
+-- Clear stack completely. Any visible screens will be hidden by navigating back out
+-- from them.
+-- @param cb (function) - Optional callback to invoke when the stack has been cleared
+function M.clear(cb)
+	log("clear() queuing action")
+
+	queue_action(function(action_done, action_error)
+		async(function(await, resume)
+			local top = stack[#stack]
+			while top and top.visible do
+				stack[#stack] = nil
+				await(back_out, top, screen, WAIT_FOR_TRANSITION, resume)
+				top = stack[#stack]
+			end
+
+			while stack[#stack] do
+				table.remove(stack)
+			end
+
+			pcallfn(cb)
+			pcallfn(action_done)
+		end)
+	end)
+end
+
+
 -- Go back to the previous screen in the stack.
 -- @param data (*) - Optional data to set for the previous screen
 -- @param cb (function) - Optional callback to invoke when the previous screen is visible again
@@ -877,6 +902,7 @@ function M.back(data, cb)
 
 	queue_action(function(action_done)
 		local callbacks = callback_tracker()
+		local back_cb = callbacks.track()
 		local screen = table.remove(stack)
 		if screen then
 			log("back()", screen.id)
@@ -888,7 +914,7 @@ function M.back(data, cb)
 					if data then
 						top.data = data
 					end
-					back_in(top, screen, WAIT_FOR_TRANSITION, callbacks.track())
+					back_in(top, screen, WAIT_FOR_TRANSITION, back_cb)
 				end)
 			else
 				if top then
@@ -896,10 +922,10 @@ function M.back(data, cb)
 						top.data = data
 					end
 					back_in(top, screen, DO_NOT_WAIT_FOR_TRANSITION, function()
-						back_out(screen, top, WAIT_FOR_TRANSITION, callbacks.track())
+						back_out(screen, top, WAIT_FOR_TRANSITION, back_cb)
 					end)
 				else
-					back_out(screen, top, WAIT_FOR_TRANSITION, callbacks.track())
+					back_out(screen, top, WAIT_FOR_TRANSITION, back_cb)
 				end
 			end
 		end

monarch/utils/async.lua

@@ -0,0 +1,47 @@
+local M = {}
+
+local NOT_STARTED = "not_started"
+local YIELDED = "yielded"
+local RESUMED = "resumed"
+local RUNNING = "running"
+
+function M.async(fn)
+	local co = coroutine.running()
+	
+	local state = NOT_STARTED
+
+	local function await(fn, ...)
+		state = RUNNING
+		fn(...)
+		if state ~= RUNNING then
+			return
+		end
+		state = YIELDED
+		local r = { coroutine.yield() }
+		return unpack(r)
+	end
+
+	local function resume(...)
+		if state ~= RUNNING then
+			state = RUNNING
+			local ok, err = coroutine.resume(co, ...)
+			if not ok then
+				print(err)
+				print(debug.traceback())
+			end
+		end
+	end
+
+	if co then
+		return fn(await, resume)
+	else
+		co = coroutine.create(fn)
+		return resume(await, resume)
+	end
+end
+
+return setmetatable(M, {
+	__call = function(t, ...)
+		return M.async(...)
+	end
+})

monarch/utils/callback_tracker.lua

@@ -6,13 +6,18 @@ function M.create()
 
 	local callback = nil
 	local callback_count = 0
+	local all_callbacks_done = false
 
 	local function is_done()
 		return callback_count == 0
 	end
 
 	local function invoke_if_done()
+		if all_callbacks_done then
+			print("Warning: The same callback will be invoked twice from the callback tracker!", id or "")
+		end
 		if callback_count == 0 and callback then
+			all_callbacks_done = true
 			local ok, err = pcall(callback)
 			if not ok then print(err) end
 		end
@@ -41,20 +46,6 @@ function M.create()
 		invoke_if_done()
 	end
 
-	function instance.yield_until_done()
-		local co = coroutine.running()
-		callback = function()
-			local ok, err = coroutine.resume(co)
-			if not ok then
-				print(err)
-			end
-		end
-		invoke_if_done()
-		if not is_done() then
-			coroutine.yield()
-		end
-	end
-
 	return instance
 end