-- This module provides easy processing of arguments passed to Scribunto from -- #invoke. It is intended for use by other Lua modules, and should not be -- called from #invoke directly.  local libraryUtil = require('libraryUtil') local checkType = libraryUtil.checkType  local arguments = {}  -- Generate four different tidyVal functions, so that we don't have to check the -- options every time we call it.  local function tidyValDefault(key, val) 	if type(val) == 'string' then 		val = val:match('^%s*(.-)%s*$') 		if val ==  then 			return nil 		else 			return val 		end 	else 		return val 	end end  local function tidyValTrimOnly(key, val) 	if type(val) == 'string' then 		return val:match('^%s*(.-)%s*$') 	else 		return val 	end end  local function tidyValRemoveBlanksOnly(key, val) 	if type(val) == 'string' then 		if val:find('%S') then 			return val 		else 			return nil 		end 	else 		return val 	end end  local function tidyValNoChange(key, val) 	return val end  local function matchesTitle(given, title) 	local tp = type( given ) 	return (tp == 'string' or tp == 'number') and mw.title.new( given ).prefixedText == title end  local translate_mt = { __index = function(t, k) return k end }  function arguments.getArgs(frame, options) 	checkType('getArgs', 1, frame, 'table', true) 	checkType('getArgs', 2, options, 'table', true) 	frame = frame or {} 	options = options or {}  	--[[ 	-- Set up argument translation. 	--]] 	options.translate = options.translate or {} 	if getmetatable(options.translate) == nil then 		setmetatable(options.translate, translate_mt) 	end 	if options.backtranslate == nil then 		options.backtranslate = {} 		for k,v in pairs(options.translate) do 			options.backtranslate[v] = k 		end 	end 	if options.backtranslate and getmetatable(options.backtranslate) == nil then 		setmetatable(options.backtranslate, { 			__index = function(t, k) 				if options.translate[k] ~= k then 					return nil 				else 					return k 				end 			end 		}) 	end  	--[[ 	-- Get the argument tables. If we were passed a valid frame object, get the 	-- frame arguments (fargs) and the parent frame arguments (pargs), depending 	-- on the options set and on the parent frame's availability. If we weren't 	-- passed a valid frame object, we are being called from another Lua module 	-- or from the debug console, so assume that we were passed a table of args 	-- directly, and assign it to a new variable (luaArgs). 	--]] 	local fargs, pargs, luaArgs 	if type(frame.args) == 'table' and type(frame.getParent) == 'function' then 		if options.wrappers then 			--[[ 			-- The wrappers option makes Module:Arguments look up arguments in 			-- either the frame argument table or the parent argument table, but 			-- not both. This means that users can use either the #invoke syntax 			-- or a wrapper template without the loss of performance associated 			-- with looking arguments up in both the frame and the parent frame. 			-- Module:Arguments will look up arguments in the parent frame 			-- if it finds the parent frame's title in options.wrapper; 			-- otherwise it will look up arguments in the frame object passed 			-- to getArgs. 			--]] 			local parent = frame:getParent() 			if not parent then 				fargs = frame.args 			else 				local title = parent:getTitle():gsub('/খেলাঘর$', ) 				local found = false 				if matchesTitle(options.wrappers, title) then 					found = true 				elseif type(options.wrappers) == 'table' then 					for _,v in pairs(options.wrappers) do 						if matchesTitle(v, title) then 							found = true 							break 						end 					end 				end  				-- We test for false specifically here so that nil (the default) acts like true. 				if found or options.frameOnly == false then 					pargs = parent.args 				end 				if not found or options.parentOnly == false then 					fargs = frame.args 				end 			end 		else 			-- options.wrapper isn't set, so check the other options. 			if not options.parentOnly then 				fargs = frame.args 			end 			if not options.frameOnly then 				local parent = frame:getParent() 				pargs = parent and parent.args or nil 			end 		end 		if options.parentFirst then 			fargs, pargs = pargs, fargs 		end 	else 		luaArgs = frame 	end  	-- Set the order of precedence of the argument tables. If the variables are 	-- nil, nothing will be added to the table, which is how we avoid clashes 	-- between the frame/parent args and the Lua args. 	local argTables = {fargs} 	argTables[#argTables + 1] = pargs 	argTables[#argTables + 1] = luaArgs  	--[[ 	-- Generate the tidyVal function. If it has been specified by the user, we 	-- use that; if not, we choose one of four functions depending on the 	-- options chosen. This is so that we don't have to call the options table 	-- every time the function is called. 	--]] 	local tidyVal = options.valueFunc 	if tidyVal then 		if type(tidyVal) ~= 'function' then 			error( 				"'valueFunc' বিকল্পে খারাপ মান আরোপিত করা হয়েছে" 					.. '(function প্রত্যাশিত, কিন্তু পাওয়া গেছে ' 					.. type(tidyVal) 					.. ')', 				2 			) 		end 	elseif options.trim ~= false then 		if options.removeBlanks ~= false then 			tidyVal = tidyValDefault 		else 			tidyVal = tidyValTrimOnly 		end 	else 		if options.removeBlanks ~= false then 			tidyVal = tidyValRemoveBlanksOnly 		else 			tidyVal = tidyValNoChange 		end 	end  	--[[ 	-- Set up the args, metaArgs and nilArgs tables. args will be the one 	-- accessed from functions, and metaArgs will hold the actual arguments. Nil 	-- arguments are memoized in nilArgs, and the metatable connects all of them 	-- together. 	--]] 	local args, metaArgs, nilArgs, metatable = {}, {}, {}, {} 	setmetatable(args, metatable)  	local function mergeArgs(tables) 		--[[ 		-- Accepts multiple tables as input and merges their keys and values 		-- into one table. If a value is already present it is not overwritten; 		-- tables listed earlier have precedence. We are also memoizing nil 		-- values, which can be overwritten if they are 's' (soft). 		--]] 		for _, t in ipairs(tables) do 			for key, val in pairs(t) do 				if metaArgs[key] == nil and nilArgs[key] ~= 'h' then 					local tidiedVal = tidyVal(key, val) 					if tidiedVal == nil then 						nilArgs[key] = 's' 					else 						metaArgs[key] = tidiedVal 					end 				end 			end 		end 	end  	--[[ 	-- Define metatable behaviour. Arguments are memoized in the metaArgs table, 	-- and are only fetched from the argument tables once. Fetching arguments 	-- from the argument tables is the most resource-intensive step in this 	-- module, so we try and avoid it where possible. For this reason, nil 	-- arguments are also memoized, in the nilArgs table. Also, we keep a record 	-- in the metatable of when pairs and ipairs have been called, so we do not 	-- run pairs and ipairs on the argument tables more than once. We also do 	-- not run ipairs on fargs and pargs if pairs has already been run, as all 	-- the arguments will already have been copied over. 	--]]  	metatable.__index = function (t, key) 		--[[ 		-- Fetches an argument when the args table is indexed. First we check 		-- to see if the value is memoized, and if not we try and fetch it from 		-- the argument tables. When we check memoization, we need to check 		-- metaArgs before nilArgs, as both can be non-nil at the same time. 		-- If the argument is not present in metaArgs, we also check whether 		-- pairs has been run yet. If pairs has already been run, we return nil. 		-- This is because all the arguments will have already been copied into 		-- metaArgs by the mergeArgs function, meaning that any other arguments 		-- must be nil. 		--]] 		if type(key) == 'string' then 			key = options.translate[key] 		end 		local val = metaArgs[key] 		if val ~= nil then 			return val 		elseif metatable.donePairs or nilArgs[key] then 			return nil 		end 		for _, argTable in ipairs(argTables) do 			local argTableVal = tidyVal(key, argTable[key]) 			if argTableVal ~= nil then 				metaArgs[key] = argTableVal 				return argTableVal 			end 		end 		nilArgs[key] = 'h' 		return nil 	end  	metatable.__newindex = function (t, key, val) 		-- This function is called when a module tries to add a new value to the 		-- args table, or tries to change an existing value. 		if type(key) == 'string' then 			key = options.translate[key] 		end 		if options.readOnly then 			error( 				'আর্গুমেন্ট টেবিল কীতে লেখা যায়নি "' 					.. tostring(key) 					.. '"; টেবিল শুধুমাত্র পাঠযোগ্য', 				2 			) 		elseif options.noOverwrite and args[key] ~= nil then 			error( 				'আর্গুমেন্ট টেবিল কীতে লেখা যায়নি "' 					.. tostring(key) 					.. '"; বিদ্যমান আর্গুমেন্টের উপর লিখন অনুমোদিত নয়', 				2 			) 		elseif val == nil then 			--[[ 			-- If the argument is to be overwritten with nil, we need to erase 			-- the value in metaArgs, so that __index, __pairs and __ipairs do 			-- not use a previous existing value, if present; and we also need 			-- to memoize the nil in nilArgs, so that the value isn't looked 			-- up in the argument tables if it is accessed again. 			--]] 			metaArgs[key] = nil 			nilArgs[key] = 'h' 		else 			metaArgs[key] = val 		end 	end  	local function translatenext(invariant) 		local k, v = next(invariant.t, invariant.k) 		invariant.k = k 		if k == nil then 			return nil 		elseif type(k) ~= 'string' or not options.backtranslate then 			return k, v 		else 			local backtranslate = options.backtranslate[k] 			if backtranslate == nil then 				-- Skip this one. This is a tail call, so this won't cause stack overflow 				return translatenext(invariant) 			else 				return backtranslate, v 			end 		end 	end  	metatable.__pairs = function () 		-- Called when pairs is run on the args table. 		if not metatable.donePairs then 			mergeArgs(argTables) 			metatable.donePairs = true 		end 		return translatenext, { t = metaArgs } 	end  	local function inext(t, i) 		-- This uses our __index metamethod 		local v = t[i + 1] 		if v ~= nil then 			return i + 1, v 		end 	end  	metatable.__ipairs = function (t) 		-- Called when ipairs is run on the args table. 		return inext, t, 0 	end  	return args end  return arguments