very simple scene management without queueing

Author: tesselode

main.lua

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+local manager = require 'roomy'.new()
+
+local state = {}
+
+state.title = {}
+
+function state.title:keypressed(key)
+	if key == 'return' then
+		manager:enter(state.gameplay, 'hi!')
+	end
+end
+
+function state.title:leave(next, ...)
+	print('leaving the title screen for', next, ...)
+end
+
+function state.title:draw()
+	love.graphics.print 'title'
+end
+
+state.gameplay = {}
+
+function state.gameplay:keypressed(key)
+	if key == 'return' then
+		manager:enter(state.title)
+	elseif key == 'space' then
+		manager:push(state.pause)
+	end
+end
+
+function state.gameplay:pause(...)
+	print('pause', ...)
+end
+
+function state.gameplay:resume(...)
+	print('resume', ...)
+end
+
+function state.gameplay:draw()
+	love.graphics.print 'gameplay'
+end
+
+state.pause = {}
+
+function state.pause:keypressed(key)
+	manager:pop(love.math.random(), love.math.random())
+end
+
+function state.pause:draw()
+	love.graphics.print 'pause'
+end
+
+function love.load()
+	manager:hook()
+	manager:enter(state.title)
+end
+
+function love.keypressed(key)
+	if key == 'escape' then love.event.quit() end
+end

roomy.lua

@@ -0,0 +1,102 @@
+local roomy = {}
+
+local loveCallbacks = {
+	'directorydropped',
+	'draw',
+	'filedropped',
+	'focus',
+	'gamepadaxis',
+	'gamepadpressed',
+	'gamepadreleased',
+	'joystickaxis',
+	'joystickhat',
+	'joystickpressed',
+	'joystickreleased',
+	'joystickremoved',
+	'keypressed',
+	'keyreleased',
+	'load',
+	'lowmemory',
+	'mousefocus',
+	'mousemoved',
+	'mousepressed',
+	'mousereleased',
+	'quit',
+	'resize',
+	'run',
+	'textedited',
+	'textinput',
+	'threaderror',
+	'touchmoved',
+	'touchpressed',
+	'touchreleased',
+	'update',
+	'visible',
+	'wheelmoved',
+	'joystickadded',
+}
+
+-- returns a list of all the items in t1 that aren't in t2
+local function exclude(t1, t2)
+	local set = {}
+	for _, item in ipairs(t1) do set[item] = true end
+	for _, item in ipairs(t2) do set[item] = nil end
+	local t = {}
+	for item, _ in pairs(set) do
+		table.insert(t, item)
+	end
+	return t
+end
+
+local Manager = {}
+Manager.__index = Manager
+
+function Manager:emit(event, ...)
+	local state = self._stack[#self._stack]
+	if state[event] then state[event](state, ...) end
+end
+
+function Manager:enter(next, ...)
+	local previous = self._stack[#self._stack]
+	self:emit('leave', next, ...)
+	self._stack[#self._stack] = next
+	self:emit('enter', previous, ...)
+end
+
+function Manager:push(next, ...)
+	local previous = self._stack[#self._stack]
+	self:emit('pause', next, ...)
+	self._stack[#self._stack + 1] = next
+	self:emit('enter', previous, ...)
+end
+
+function Manager:pop(...)
+	local previous = self._stack[#self._stack]
+	local next = self._stack[#self._stack - 1]
+	self:emit('leave', next, ...)
+	self._stack[#self._stack] = nil
+	self:emit('resume', previous, ...)
+end
+
+function Manager:hook(options)
+	options = options or {}
+	local callbacks = options.include or loveCallbacks
+	if options.exclude then
+		callbacks = exclude(callbacks, options.exclude)
+	end
+	for _, callbackName in ipairs(callbacks) do
+		local oldCallback = love[callbackName]
+		love[callbackName] = function(...)
+			if oldCallback then oldCallback(...) end
+			self:emit(callbackName, ...)
+		end
+	end
+end
+
+function roomy.new()
+	return setmetatable({
+		_stack = {{}},
+	}, Manager)
+end
+
+return roomy