From 62ff5245c26c305e35a2903cc64a60cb20718e96 Mon Sep 17 00:00:00 2001
From: Indrajith K L
Date: Sun, 27 Feb 2022 01:15:31 +0530
Subject: Initial Commit

* ECS - In-Progress
* GameStates - Skeleton Implemented
* Library Integrations - Completed
* Levels - In-Progress
---
 libs/hump/gamestate.lua | 116 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 libs/hump/gamestate.lua

(limited to 'libs/hump/gamestate.lua')

diff --git a/libs/hump/gamestate.lua b/libs/hump/gamestate.lua
new file mode 100644
index 0000000..059dbb9
--- /dev/null
+++ b/libs/hump/gamestate.lua
@@ -0,0 +1,116 @@
+--[[
+Copyright (c) 2010-2013 Matthias Richter
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+Except as contained in this notice, the name(s) of the above copyright holders
+shall not be used in advertising or otherwise to promote the sale, use or
+other dealings in this Software without prior written authorization.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+]]--
+
+local function __NULL__() end
+
+ -- default gamestate produces error on every callback
+local state_init = setmetatable({leave = __NULL__},
+		{__index = function() error("Gamestate not initialized. Use Gamestate.switch()") end})
+local stack = {state_init}
+local initialized_states = setmetatable({}, {__mode = "k"})
+local state_is_dirty = true
+
+local GS = {}
+function GS.new(t) return t or {} end -- constructor - deprecated!
+
+local function change_state(stack_offset, to, ...)
+	local pre = stack[#stack]
+
+	-- initialize only on first call
+	;(initialized_states[to] or to.init or __NULL__)(to)
+	initialized_states[to] = __NULL__
+
+	stack[#stack+stack_offset] = to
+	state_is_dirty = true
+	return (to.enter or __NULL__)(to, pre, ...)
+end
+
+function GS.switch(to, ...)
+	assert(to, "Missing argument: Gamestate to switch to")
+	assert(to ~= GS, "Can't call switch with colon operator")
+	;(stack[#stack].leave or __NULL__)(stack[#stack])
+	return change_state(0, to, ...)
+end
+
+function GS.push(to, ...)
+	assert(to, "Missing argument: Gamestate to switch to")
+	assert(to ~= GS, "Can't call push with colon operator")
+	return change_state(1, to, ...)
+end
+
+function GS.pop(...)
+	assert(#stack > 1, "No more states to pop!")
+	local pre, to = stack[#stack], stack[#stack-1]
+	stack[#stack] = nil
+	;(pre.leave or __NULL__)(pre)
+	state_is_dirty = true
+	return (to.resume or __NULL__)(to, pre, ...)
+end
+
+function GS.current()
+	return stack[#stack]
+end
+
+-- XXX: don't overwrite love.errorhandler by default:
+--      this callback is different than the other callbacks
+--      (see http://love2d.org/wiki/love.errorhandler)
+--      overwriting thi callback can result in random crashes (issue #95)
+local all_callbacks = { 'draw', 'update' }
+
+-- fetch event callbacks from love.handlers
+for k in pairs(love.handlers) do
+	all_callbacks[#all_callbacks+1] = k
+end
+
+function GS.registerEvents(callbacks)
+	local registry = {}
+	callbacks = callbacks or all_callbacks
+	for _, f in ipairs(callbacks) do
+		registry[f] = love[f] or __NULL__
+		love[f] = function(...)
+			registry[f](...)
+			return GS[f](...)
+		end
+	end
+end
+
+local function_cache = {}
+
+-- forward any undefined functions
+setmetatable(GS, {__index = function(_, func)
+	-- call function only if at least one 'update' was called beforehand
+	-- (see issue #46)
+	if not state_is_dirty or func == 'update' then
+		state_is_dirty = false
+		function_cache[func] = function_cache[func] or function(...)
+			return (stack[#stack][func] or __NULL__)(stack[#stack], ...)
+		end
+		return function_cache[func]
+	end
+	return __NULL__
+end})
+
+return GS
-- 
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