lua_enum/enum.lua at main · Peter-Greek/lua_enum · GitHub

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local ENUM_RUN_TESTS = true

local function _pair(k, v, is_auto)

return { __enum_key = k, __enum_val = v, __enum_auto = is_auto == true }

end

local function _symbol(name)

return function(v)

-- if user wrote NAME (x) then v is provided

if v ~= nil then

return _pair(name, v, false)

end

-- if user wrote NAME with no parentheses, we need a bare value in the list

-- but Lua cannot place a function call-less identifier into a list without evaluating it

-- so we return an auto marker by making the symbol itself evaluate to this marker:

return _pair(name, nil, true)

end

local function _build(list)

local enum = {}

local next_auto = 1

for i = 1, #list do

local item = list[i]

if type(item) == "table" and item.__enum_key ~= nil then

local key = item.__enum_key

if item.__enum_auto then

enum[key] = next_auto

next_auto = next_auto + 1

else

local v = item.__enum_val

enum[key] = v

-- C++ style: after explicit value, next implicit continues from v+1

if type(v) == "number" then

next_auto = v + 1

end

return enum

end

local function _stack_contains_func(target_func, max_depth)

max_depth = max_depth or 12

for level = 2, max_depth do

local info = debug.getinfo(level, "f")

if not info then break end

if info.func == target_func then

return true

end

return false

end

ENUM = setmetatable({}, {

__call = function(_, enumName)

local prev_mt = getmetatable(_G)

local prev_index = prev_mt and prev_mt.__index or nil

-- function that invoked: ENUM "NAME"

local caller = debug.getinfo(2, "f").func

local caller_co = coroutine.running()

local sym_cache = {}

local function guarded_index(t, k)

-- preserve any prior __index behavior

if type(prev_index) == "function" then

local v = prev_index(t, k)

if v ~= nil then return v end

elseif type(prev_index) == "table" then

local v = prev_index[k]

if v ~= nil then return v end

end

-- real globals

local v = rawget(t, k)

if v ~= nil then return v end

-- only during the same call chain + same coroutine

if coroutine.running() ~= caller_co then

return nil

end

if not _stack_contains_func(caller) then

return nil

end

v = sym_cache[k]

if not v then

-- IMPORTANT: return a value that can appear in the list without parentheses

-- We make the global lookup itself return the AUTO marker table,

-- but we also want parentheses support. So we return a callable table:

local auto_marker = _pair(k, nil, true)

v = setmetatable(auto_marker, {

__call = function(_, arg)

return _pair(k, arg, false)

end

})

sym_cache[k] = v

end

return v

end

local tmp_mt = {}

if prev_mt then

for k, v in pairs(prev_mt) do

tmp_mt[k] = v

end

tmp_mt.__index = guarded_index

setmetatable(_G, tmp_mt)

return function(list)

setmetatable(_G, prev_mt)

local enum = _build(list)

rawset(_G, enumName, enum)

return enum

end

})

if ENUM_RUN_TESTS then

-- note: use ENUM

local x = ENUM "HOUSING_e" ({

APARTMENT, -- 1

HOUSE, -- 2

MANSION, -- 3

SHOP(10), -- 10

OFFICE, -- 11

WAREHOUSE(20), -- 20

GARAGE, -- 21

TRAILER, -- 22

HIGHENDAPARTMENT, -- 23

})

print(HOUSING_e.APARTMENT, HOUSING_e.HIGHENDAPARTMENT, HOUSING_e.NONEXISTENT)

end

return ENUM

lua_enum/enum.lua at main · Peter-Greek/lua_enum · GitHub

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