Manuel Simon Hirsig
40 lines
1.5 KiB
Lua
40 lines
1.5 KiB
Lua
local PUBLIC, PRIVATE = 1, 2
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local state = {}
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local interface_mt = {
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__index = function(self, key)
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if not state[self].access[state[self].type][key] then
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error('Read of undeclared "'..key..'".', 2)
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end
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return state[self].data[key]
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end,
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__newindex = function(self, key, value)
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if state[self].type == PUBLIC then
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error('Unsupported operation.', 2)
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elseif not state[self].access[PRIVATE][key] then
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error('Write of undeclared "'..key..'".', 2)
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end
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state[self].data[key] = value
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end,
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}
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local declarator_mt = {
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__index = function()
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error('Unsupported operation.', 2)
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end,
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__newindex = function(self, key, value)
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if state[self].access[PRIVATE][key] then
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error('Multiple declarations of "'..key..'".', 2)
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end
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state[self].data[key] = value
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state[self].access[PRIVATE][key] = true
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state[self].access[state[self].type][key] = true
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end,
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}
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function aux_module()
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local data, access = {}, {{}, {}}
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local public_state, private_state = {type=PUBLIC, data=data, access=access}, {type=PRIVATE, data=data, access=access}
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local public_interface, private_interface = setmetatable({}, interface_mt), setmetatable({}, interface_mt)
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local public_declarator, private_declarator = setmetatable({}, declarator_mt), setmetatable({}, declarator_mt)
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state[public_interface], state[private_interface] = public_state, private_state
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state[public_declarator], state[private_declarator] = public_state, private_state
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return public_interface, private_interface, public_declarator, private_declarator
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end |