hump/class.lua
2012-04-10 17:00:02 +02:00

101 lines
3.4 KiB
Lua

--[[
Copyright (c) 2010-2012 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
-- class "inheritance" by copying functions
local function inherit(class, interface, ...)
if not interface then return end
assert(type(interface) == "table", "Can only inherit from other classes.")
-- __index and construct are not overwritten as for them class[name] is defined
for name, func in pairs(interface) do
if not class[name] then
class[name] = func
end
end
for super in pairs(interface.__is_a or {}) do
class.__is_a[super] = true
end
return inherit(class, ...)
end
-- class builder
local function new(args)
local super = {}
local name = '<unnamed class>'
local constructor = args or __NULL__
if type(args) == "table" then
-- nasty hack to check if args.inherits is a table of classes or a class or nil
super = (args.inherits or {}).__is_a and {args.inherits} or args.inherits or {}
name = args.name or name
constructor = args[1] or __NULL__
end
assert(type(constructor) == "function", 'constructor has to be nil or a function')
-- build class
local class = {}
class.__index = class
class.__tostring = function() return ("<instance of %s>"):format(tostring(class)) end
class.construct = constructor or __NULL__
class.inherit = inherit
class.__is_a = {[class] = true}
class.is_a = function(self, other) return not not self.__is_a[other] end
-- inherit superclasses (see above)
inherit(class, unpack(super))
-- syntactic sugar
local meta = {
__call = function(self, ...)
local obj = {}
setmetatable(obj, self)
self.construct(obj, ...)
return obj
end,
__tostring = function() return name end
}
return setmetatable(class, meta)
end
-- interface for cross class-system compatibility (see https://github.com/bartbes/Class-Commons).
if class_commons ~= false and not common then
common = {}
function common.class(name, prototype, parent)
local init = prototype.init or (parent or {}).init
return new{name = name, inherits = {prototype, parent}, init}
end
function common.instance(class, ...)
return class(...)
end
end
-- the module
return setmetatable({new = new, inherit = inherit},
{__call = function(_,...) return new(...) end})