Module:Arguments

-- 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 local parent = frame:getParent if not parent then fargs = frame.args else local title = parent:getTitle:gsub('/sandbox$', '') 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(				"bad value assigned to option 'valueFunc'"					.. '(function expected, got ' .. 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(				'could not write to argument table key "'					.. tostring(key)					.. '"; the table is read-only',				2			) elseif options.noOverwrite and args[key] ~= nil then error(				'could not write to argument table key "'					.. tostring(key)					.. '"; overwriting existing arguments is not permitted',				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

-- imported from wikipedia