Module:GetArgs

--[[ Handles most of the boilerplate necessary to fetch arguments, such as trimming leading/trailing whitespace, making blank arguments evaluate to false, correctly choosing between current-frame and parent-frame, etc.

Originally written on the English Wikipedia by Mr. Stradivarius, Jackmcbarn, and Anomie.

Code released under the GPL v2+ as per: https://en.wikipedia.org/w/index.php?diff=624020648&oldid=624019645 https://en.wikipedia.org/w/index.php?diff=624073793&oldid=624020648

@license GNU GPL v2+ ]]

local libraryUtil = require( 'libraryUtil' )

local sandboxSuffixPattern = string.format( '/%s$', mw.message.new( 'scribunto-template-sandbox-subpage-name' ):plain():gsub("%p", "%%%0") )

local function tidyValDefault( k, v ) if type( v ) == 'string' then v = v:match( '^%s*(.-)%s*$' ) if v == then return nil end end return v end

local function tidyValTrimOnly( k, v ) if type( v ) == 'string' then return v:match( '^%s*(.-)%s*$' ) else return v end end

local function tidyValRemoveBlanksOnly( k, v ) if type( v ) == 'string' and not v:find( '%S' ) then return nil else return v end end

local function tidyValNoChange( k, v ) return v end

local function matchesTitle( given, title ) local tp = type( given ) return ( tp == 'string' or tp == 'number' ) and mw.title.new( given ).prefixedText == title end

-- Checks whether title matches any wrapper templates that were specified by -- the user. local function titleIsWrapper( title, wrappers ) title = title:gsub( sandboxSuffixPattern, ) if matchesTitle( wrappers, title ) then return true elseif type( wrappers ) == 'table' then -- If either a key or a value matches, it's a match if wrappers[title] ~= nil then return true else for _,v in ipairs( wrappers ) do if matchesTitle( v, title ) then return true end end end end return false end

return function( options ) libraryUtil.checkType( 'getArgs', 1, options, 'table', true ) local frame = options.frame if frame == nil then return {} end libraryUtil.checkTypeForNamedArg( 'getArgs', 'frame', frame, 'table' )

--[[ -- Get the tables to look up arguments from. These could be any of: -- * the frame arguments -- * the parent frame arguments -- * a table of arguments passed from a Lua module or from the debug console -- We try to select the correct one(s) based on whether we were passed a -- valid frame object and whether we are being called from a wrapper -- template. Usually we only use one of these tables, but if -- options.wrappersUseFrame is set we may use both the frame arguments and -- the parent frame arguments. --]] local argTables = {} if type( frame.args ) == 'table' and type( frame.getParent ) == 'function' then -- We were passed a valid frame. Find out if the title of its parent -- frame is contained in options.wrappers. if options.wrappers then local parent = frame:getParent() if parent and titleIsWrapper( parent:getTitle(), options.wrappers ) then argTables[1] = parent.args end end if not argTables[1] or options.wrappersUseFrame then table.insert( argTables, frame.args ) end else -- Assume frame is a table of arguments passed from a Lua module or -- from the debug console. argTables[1] = frame end

-- Get tidyVal, the function that we use to trim whitespace and remove -- blank arguments. This can be set by the user with options.valueFunc. -- Otherwise it is generated from options.trim and options.removeBlanks. -- We define four separate default tidyVal functions so that we can avoid -- checking options.trim and options.removeBlanks every time we look up an -- argument. local tidyVal = options.valueFunc if tidyVal then libraryUtil.checkTypeForNamedArg( 'getArgs', 'valueFunc', tidyVal, 'function' ) 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 a metatable to allow transparent fetching of arguments from argTables -- * mt - the metatable -- * fetchedArgs - a table to store memoized arguments fetched from argTables -- * nilArgs - a table to memoize nil arguments -- * donePairs - whether pairs has been run -- * doneIpairs - whether ipairs has been run local mt, fetchedArgs, nilArgs = {}, {}, {} local donePairs, doneIpairs = false, false

-- This function merges arguments from argument tables into fetchedArgs, -- Earlier argument tables take precedence over later ones; once a value -- is written it is not overwritten. local function mergeArgs( tables ) for _, t in ipairs( tables ) do for key, val in pairs( t ) do if fetchedArgs[key] == nil and not nilArgs[key] then local tidiedVal = tidyVal( key, val ) if tidiedVal == nil then nilArgs[key] = true else fetchedArgs[key] = tidiedVal end end end end end

function mt.__index( t, key ) local val = fetchedArgs[key] if val ~= nil then return val elseif donePairs or nilArgs[key] then -- If pairs has been run we already have all the arguments in -- fetchedArgs. return nil end for _, argTable in ipairs( argTables ) do local argTableVal = tidyVal( key, argTable[key] ) if argTableVal ~= nil then fetchedArgs[key] = argTableVal return argTableVal end end nilArgs[key] = true return nil end

function mt.__newindex( t, key, val ) if val == nil then -- We need to memoize the nil so that we don't look up the key in -- the argument tables if it is accessed again. nilArgs[key] = true end fetchedArgs[key] = val end

function mt.__pairs() if not donePairs then donePairs = true mergeArgs( argTables ) end return pairs( fetchedArgs ) 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

function mt.__ipairs(t) return inext, t, 0 end

return setmetatable( {}, mt ) end