Module:Sandbox/Jackmcbarn: Difference between revisions

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local translationwrapper = {}

local function translatenext(invariant)
	local k, v = next(invariant.args.src, invariant.k)
	invariant.k = k
	if k == nil then
		return nil
	elseif type(k) ~= 'string' then
		return k, v
	end
	local from = invariant.args.from[k]
	if from ~= nil then
		return from, v
	elseif invariant.args.to[k] == nil then
		return k, v
	else
		-- skip this key. tail call
		return translatenext(invariant)
	end
end
function translationwrapper.create(args)
	-- args.to contains English keys and translated values
	-- if the value is a table, any of that table's values are valid translations
	-- args.from contains translated keys and English values
	-- optional if args.to doesn't rely on __index
	-- args.src is the table being wrapped
	if not args.from then
		args.from = {}
		for k,v in pairs(args.to) do
			args.from[v] = k
		end
	end

	local mt = {}
	function mt.__index(t, k)
		if type(k) == 'string' then
			local retval = args.src[args.to[k]]
			if retval ~= nil or args.from[k] ~= nil then
				return retval
			end
		end
		return args.src[k]
	end
	function mt.__newindex(t, k, v)
		if type(k) ~= 'string' then
			args.src[k] = v
			return
		end
		local to = args.to[k]
		local falseCognate = args.from[k] ~= nil
		if to ~= nil then
			if v == nil and not falseCognate then
				args.src[k] = nil
			end
			args.src[to] = v
		elseif not falseCognate then
			args.src[k] = v
		else
			error('Attempt to write key "' .. k .. '" which has no translation and is a false cognate', 2)
		end
	end
	function mt.__pairs(t)
		return translatenext, {args = args}
	end
	function mt.__ipairs(t)
		return ipairs(args.src)
	end
	return setmetatable({}, mt)
end

local p = {}

function p.main(frame)
	local args = {
		eins = '#ff0000',
		zwei = '#ff7f00',
		drei = '#FFFF00',
		three = 'yellow'
	}
	local to = {
		one = 'eins',
		two = 'zwei',
		three = 'drei'
	}
	local wrapper = translationwrapper.create{src = args, to = to}
	return wrapper
end

return p