Module:Arguments

Revision as of 08:17, 9 December 2013 by Mr. Stradivarius (talk) (check fargs and pargs before writing new values to args if options.noOverwrite is set)

-- 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 assume arguments are passed directly in. local fargs, pargs if frame == mw.getCurrentFrame() then fargs = frame.args pargs = frame:getParent().args else fargs = type(frame) == 'table' and frame or {} pargs = {} end

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 functions 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, ...) -- 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. local tables = {...} 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 frame args and parent args. local firstArgs, secondArgs = fargs, pargs if options.parentFirst then firstArgs, secondArgs = pargs, fargs end

--[[ -- Define metatable behaviour. Arguments are stored in the metaArgs table, and are only fetched from the -- fargs and pargs 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 local firstVal = tidyVal(key, firstArgs[key]) if firstVal ~= nil then return firstVal else return tidyVal(key, secondArgs[key]) 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, firstArgs, secondArgs) metatable.donePairs = true metatable.doneIpairs = true end return pairs(metaArgs) end

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

return args end

return arguments