Manuel Simon Hirsig
108 lines
4.0 KiB
Lua
108 lines
4.0 KiB
Lua
if module then return end
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local setfenv, setmetatable, unpack, _G = setfenv, setmetatable, unpack, getfenv(0)
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local PRIVATE, FIELD, PUBLIC, ACCESSOR, MUTATOR = 0, 0, 1, 2, 4
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local PUBLIC_FIELD, PUBLIC_ACCESSOR, PUBLIC_MUTATOR = PUBLIC+FIELD, PUBLIC+ACCESSOR, PUBLIC+MUTATOR
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local function error(msg, ...) return _G.error(format(msg or '', unpack(arg)) .. '\n' .. debugstack(), 0) end
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local function import_error() error('Import error.') end
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local function declaration_error() error('Declaration error.') end
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local function collision_error(key) error('"%s" already exists.', key) end
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local nop, id = function() end, function(v) return v end
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local interface_eq = function() return true end
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local interface_mt, environment_mt, declarator_mt = { __metatable=false, __eq=interface_eq }, { __metatable=false }, { __metatable=false }
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local INTERFACE = setmetatable({}, { __eq=interface_eq })
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local __ = {}
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function interface_mt:__index(k) self=__[self]
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return self[PUBLIC_FIELD][k]
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end
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function interface_mt:__newindex(k, v) self=__[self]
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self[PUBLIC_MUTATOR][k](v)
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end
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function environment_mt:__index(k) self=__[self]
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return self[FIELD][k]
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end
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function environment_mt:__newindex(k, v) self=__[self]
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local mutator = self[MUTATOR][k]
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if mutator then
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mutator(v)
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elseif not self.defined[k] or collision_error(k) then
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self.declarator[k] = v
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end
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end
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do
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local ACCESS, META = { public=PUBLIC, private=PRIVATE }, { get=ACCESSOR, set=MUTATOR }
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function declarator_mt:__index(k) self=__[self]
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if not self.declaration_access then
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self.declaration_access = ACCESS[k] or declaration_error()
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elseif not self.declaration_meta or declaration_error() then
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self.declaration_meta = META[k]
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self.declaration_modifiers[k] = true
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end
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return self.declarator
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end
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function declarator_mt:__newindex(k, v) self=__[self]
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local access, meta = self.declaration_access, self.declaration_meta or FIELD
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if v ~= self.interface then
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self.defined[k] = true
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self[meta], self[access+meta] = v, v -- TODO performance assignment vs conditional
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elseif _G[k] ~= nil or error(nil) then
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_G[k] = v
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end
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self.declaration_access, self.declaration_meta = nil, nil
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end
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function declarator_mt:__call()
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self.default_access = (not self.declaration_meta or declaration_error()) and self.declaration_access
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end
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end
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local function import(self, interface)
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local module = (interface == INTERFACE or import_error()) and __[interface]
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for k, v in module[PUBLIC_FIELD] do
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if not self.defined[k] then
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self.defined[k], self[FIELD][k] = true, v
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end
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end
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for k, v in module[PUBLIC_ACCESSOR] do
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if not self.defined[k] then
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self.defined[k], self[ACCESSOR][k] = true, v
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end
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end
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for k, v in module[PUBLIC_MUTATOR] do
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if not self.defined[k] then
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self.defined[k], self[MUTATOR][k] = true, v
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end
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end
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end
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local nop_mt = { __index=nop }
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local mt = { __metatable=false }
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function mt:__index(key)
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if key ~= 'module' then return end
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local interface, environment, declarator = setmetatable({}, interface_mt), setmetatable({}, environment_mt), setmetatable({}, declarator_mt)
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local accessors, public_accessors = setmetatable({}, { __index=_G }), {}
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self = {
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defined = { _G=true, _I=true, _E=true, public=true, private=true, import=true, _=true, error=true, nop=true, id=true },
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[FIELD] = setmetatable(
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{ _G=_G, _I=interface, _E=environment, import=function(interface) import(self, interface) end, error=error, nop=nop, id=id },
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{__index=function(_, key) return accessors[key]() end }
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),
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[ACCESSOR] = setmetatable({ public=function() return declarator.public end, private=function() return declarator.private end }, nop_mt),
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[MUTATOR] = setmetatable({}, nop_mt),
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[PUBLIC_FIELD] = setmetatable({}, {__index=function(_, key) return public_accessors[key]() end}),
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[PUBLIC_ACCESSOR] = setmetatable({}, nop_mt),
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[PUBLIC_MUTATOR] = setmetatable({}, nop_mt),
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interface = interface,
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declarator = declarator,
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}
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__[interface], __[environment], __[declarator] = self, self, self
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setfenv(2, environment)
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return interface
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end
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setmetatable(_G, mt) |