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.

 locallibraryUtil=require('libraryUtil')
 localcheckType=libraryUtil.checkType

 localarguments={}

 -- Generate four different tidyVal functions, so that we don't have to check the
 -- options every time we call it.

 localfunctiontidyValDefault(key,val)
 iftype(val)=='string'then
 val=val:match('^%s*(.-)%s*$')
 ifval==''then
 returnnil
 else
 returnval
 end
 else
 returnval
 end
 end

 localfunctiontidyValTrimOnly(key,val)
 iftype(val)=='string'then
 returnval:match('^%s*(.-)%s*$')
 else
 returnval
 end
 end

 localfunctiontidyValRemoveBlanksOnly(key,val)
 iftype(val)=='string'then
 ifval:find('%S')then
 returnval
 else
 returnnil
 end
 else
 returnval
 end
 end

 localfunctiontidyValNoChange(key,val)
 returnval
 end

 localfunctionmatchesTitle(given,title)
 localtp=type(given)
 return(tp=='string'ortp=='number')andmw.title.new(given).prefixedText==title
 end

 localtranslate_mt={__index=function(t,k)returnkend}

 functionarguments.getArgs(frame,options)
 checkType('getArgs',1,frame,'table',true)
 checkType('getArgs',2,options,'table',true)
 frame=frameor{}
 options=optionsor{}

 --[[
 	-- Set up argument translation.
 	--]]
 options.translate=options.translateor{}
 ifgetmetatable(options.translate)==nilthen
 setmetatable(options.translate,translate_mt)
 end
 ifoptions.backtranslate==nilthen
 options.backtranslate={}
 fork,vinpairs(options.translate)do
 options.backtranslate[v]=k
 end
 end
 ifoptions.backtranslateandgetmetatable(options.backtranslate)==nilthen
 setmetatable(options.backtranslate,{
 __index=function(t,k)
 ifoptions.translate[k]~=kthen
 returnnil
 else
 returnk
 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).
 	--]]
 localfargs,pargs,luaArgs
 iftype(frame.args)=='table'andtype(frame.getParent)=='function'then
 ifoptions.wrappersthen
 --[[
 			-- 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.
 			--]]
 localparent=frame:getParent()
 ifnotparentthen
 fargs=frame.args
 else
 localtitle=parent:getTitle():gsub('/sandbox$','')
 localfound=false
 ifmatchesTitle(options.wrappers,title)then
 found=true
 elseiftype(options.wrappers)=='table'then
 for_,vinpairs(options.wrappers)do
 ifmatchesTitle(v,title)then
 found=true
 break
 end
 end
 end

 -- We test for false specifically here so that nil (the default) acts like true.
 iffoundoroptions.frameOnly==falsethen
 pargs=parent.args
 end
 ifnotfoundoroptions.parentOnly==falsethen
 fargs=frame.args
 end
 end
 else
 -- options.wrapper isn't set, so check the other options.
 ifnotoptions.parentOnlythen
 fargs=frame.args
 end
 ifnotoptions.frameOnlythen
 localparent=frame:getParent()
 pargs=parentandparent.argsornil
 end
 end
 ifoptions.parentFirstthen
 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.
 localargTables={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.
 	--]]
 localtidyVal=options.valueFunc
 iftidyValthen
 iftype(tidyVal)~='function'then
 error(
 "bad value assigned to option 'valueFunc'"
 ..'(function expected, got '
 ..type(tidyVal)
 ..')',
 2
 )
 end
 elseifoptions.trim~=falsethen
 ifoptions.removeBlanks~=falsethen
 tidyVal=tidyValDefault
 else
 tidyVal=tidyValTrimOnly
 end
 else
 ifoptions.removeBlanks~=falsethen
 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.
 	--]]
 localargs,metaArgs,nilArgs,metatable={},{},{},{}
 setmetatable(args,metatable)

 localfunctionmergeArgs(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_,tinipairs(tables)do
 forkey,valinpairs(t)do
 ifmetaArgs[key]==nilandnilArgs[key]~='h'then
 localtidiedVal=tidyVal(key,val)
 iftidiedVal==nilthen
 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.
 		--]]
 iftype(key)=='string'then
 key=options.translate[key]
 end
 localval=metaArgs[key]
 ifval~=nilthen
 returnval
 elseifmetatable.donePairsornilArgs[key]then
 returnnil
 end
 for_,argTableinipairs(argTables)do
 localargTableVal=tidyVal(key,argTable[key])
 ifargTableVal~=nilthen
 metaArgs[key]=argTableVal
 returnargTableVal
 end
 end
 nilArgs[key]='h'
 returnnil
 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.
 iftype(key)=='string'then
 key=options.translate[key]
 end
 ifoptions.readOnlythen
 error(
 'could not write to argument table key "'
 ..tostring(key)
 ..'"; the table is read-only',
 2
 )
 elseifoptions.noOverwriteandargs[key]~=nilthen
 error(
 'could not write to argument table key "'
 ..tostring(key)
 ..'"; overwriting existing arguments is not permitted',
 2
 )
 elseifval==nilthen
 --[[
 			-- 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

 localfunctiontranslatenext(invariant)
 localk,v=next(invariant.t,invariant.k)
 invariant.k=k
 ifk==nilthen
 returnnil
 elseiftype(k)~='string'ornotoptions.backtranslatethen
 returnk,v
 else
 localbacktranslate=options.backtranslate[k]
 ifbacktranslate==nilthen
 -- Skip this one. This is a tail call, so this won't cause stack overflow
 returntranslatenext(invariant)
 else
 returnbacktranslate,v
 end
 end
 end

 metatable.__pairs=function()
 -- Called when pairs is run on the args table.
 ifnotmetatable.donePairsthen
 mergeArgs(argTables)
 metatable.donePairs=true
 end
 returntranslatenext,{t=metaArgs}
 end

 localfunctioninext(t,i)
 -- This uses our __index metamethod
 localv=t[i+1]
 ifv~=nilthen
 returni+1,v
 end
 end

 metatable.__ipairs=function(t)
 -- Called when ipairs is run on the args table.
 returninext,t,0
 end

 returnargs
 end

 returnarguments