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 arguments = {}

function arguments.getArgs(frame, options) options = type(options) == 'table' and options or {}

-- Get the arguments from the frame object if available. If the frame object is not available, we are being called -- from another Lua module or from the debug console, so put the args in a special table so we can differentiate them. local fargs, pargs, luaArgs if type(frame) == 'table' and type(frame.args) == 'table' and type(frame.getParent) == 'function' then fargs = frame.args pargs = frame:getParent().args else luaArgs = type(frame) == 'table' and frame or {} end

-- Set up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments. -- The metatable connects the two together. local args, metaArgs, metatable = {}, {}, {} setmetatable(args, metatable)

local function tidyVal(key, val) -- Processes a value according to the options given to getArguments. Can trim whitespace and remove blanks. -- Keys are not used here, but they can be used by user-generated functions, so defining it here to avoid breakage. if type(val) == 'string' then if options.trim ~= false then val = mw.text.trim(val) end if options.removeBlanks == false or mw.ustring.find(val, '%S') then return val end else return val end end

-- Use a user-generated function to tidy the values if specified. local valueFunc = options.valueFunc if valueFunc then local valueFuncType = type(valueFunc) if valueFuncType == 'function' then tidyVal = valueFunc else error('type error in option "valueFunc": expected function, got ' .. valueFuncType, 2) end end

local function mergeArgs(iterator, tables) -- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator. -- If a value is already present it is not overwritten; tables listed earlier have precendence. for _, t in ipairs(tables) do for key, val in iterator(t) do if metaArgs[key] == nil then metaArgs[key] = tidyVal(key, val) end end end 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 = {} if options.frameOnly then table.insert(argTables, fargs) elseif options.parentOnly then table.insert(argTables, pargs) elseif options.parentFirst then table.insert(argTables, pargs) table.insert(argTables, fargs) else table.insert(argTables, fargs) table.insert(argTables, pargs) end table.insert(argTables, luaArgs)

--[[ -- Define metatable behaviour. Arguments are stored in the metaArgs table, and are only fetched from the -- argument tables once. 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 fargs and pargs 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) local val = metaArgs[key] if val ~= nil then return val else for i, argTable in ipairs(argTables) do local argTableVal = tidyVal(key, argTable[key]) if argTableVal ~= nil then metaArgs[key] = argTableVal return argTableVal end end end end

metatable.__newindex = function (t, key, val) if not options.readOnly and (not options.noOverwrite or args[key] == nil) then metaArgs[key] = val end end

metatable.__pairs = function () if not metatable.donePairs then mergeArgs(pairs, argTables) metatable.donePairs = true metatable.doneIpairs = true end return pairs(metaArgs) end

metatable.__ipairs = function () if not metatable.doneIpairs then mergeArgs(ipairs, argTables) metatable.doneIpairs = true end return ipairs(metaArgs) end

return args end

return arguments