Module:Arguments: Difference between revisions

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m>Mr. Stradivarius
fix undefined next() behaviour bug by checking for metatable.donePairs in the __index metamethod; also, format the module so it fits into 80 characters
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local arguments = {}
local arguments = {}
local nilArg = {} -- Used for memoizing nil arguments in metaArgs.


-- Generate four different tidyVal functions, so that we don't have to check the
-- Generate four different tidyVal functions, so that we don't have to check the
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return val
return val
end
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)
function arguments.getArgs(frame, options)
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--[[
--[[
-- Get the arguments from the frame object if available. If the frame object
-- Set up argument translation.
-- is not available, we are being called from another Lua module or from the
--]]
-- debug console, so assign the args to a new variable so we can
options.translate = options.translate or {}
-- differentiate them.
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
local fargs, pargs, luaArgs
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
if not options.parentOnly then
if options.wrappers then
fargs = frame.args
--[[
end
-- The wrappers option makes Module:Arguments look up arguments in
if not options.frameOnly then
-- either the frame argument table or the parent argument table, but
pargs = frame:getParent().args
-- 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.
--]]
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
end
if options.parentFirst then
if options.parentFirst then
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end
end


-- Set up the args and metaArgs tables. args will be the one accessed from
-- Set the order of precedence of the argument tables. If the variables are
-- functions, and metaArgs will hold the actual arguments. The metatable
-- nil, nothing will be added to the table, which is how we avoid clashes
-- connects the two together.
-- between the frame/parent args and the Lua args.
local args, metaArgs, metatable = {}, {}, {}
local argTables = {fargs}
setmetatable(args, metatable)
argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = luaArgs


--[[
--[[
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end
end


local function mergeArgs(iterator, tables)
--[[
-- 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
-- Accepts multiple tables as input and merges their keys and values
-- into one table using the specified iterator. If a value is already
-- into one table. If a value is already present it is not overwritten;
-- present it is not overwritten; tables listed earlier have precedence.
-- tables listed earlier have precedence. We are also memoizing nil
-- We are also memoizing nil values, but those values can be
-- values, which can be overwritten if they are 's' (soft).
-- overwritten.
--]]
--]]
for _, t in ipairs(tables) do
for _, t in ipairs(tables) do
for key, val in iterator(t) do
for key, val in pairs(t) do
local metaArgsVal = metaArgs[key]
if metaArgs[key] == nil and nilArgs[key] ~= 'h' then
if metaArgsVal == nil or metaArgsVal == nilArg then
local tidiedVal = tidyVal(key, val)
local tidiedVal = tidyVal(key, val)
if tidiedVal == nil then
if tidiedVal == nil then
metaArgs[key] = nilArg
nilArgs[key] = 's'
else
else
metaArgs[key] = tidiedVal
metaArgs[key] = tidiedVal
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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 = {fargs}
argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = luaArgs


--[[
--[[
-- Define metatable behaviour. Arguments are memoized in the metaArgs table,
-- Define metatable behaviour. Arguments are memoized in the metaArgs table,
-- and are only fetched from the argument tables once. Nil arguments are
-- and are only fetched from the argument tables once. Fetching arguments
-- also memoized using the nilArg variable in order to increase performance.
-- from the argument tables is the most resource-intensive step in this
-- Also, we keep a record in the metatable of when pairs and ipairs have
-- module, so we try and avoid it where possible. For this reason, nil
-- been called, so we do not run pairs and ipairs on fargs and pargs more
-- arguments are also memoized, in the nilArgs table. Also, we keep a record
-- than once. We also do not run ipairs on fargs and pargs if pairs has
-- in the metatable of when pairs and ipairs have been called, so we do not
-- already been run, as all the arguments will already have been copied
-- run pairs and ipairs on the argument tables more than once. We also do
-- over.
-- 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)
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]
local val = metaArgs[key]
if metatable.donePairs or val ~= nil then
if val ~= nil then
--[[
return val
-- We have either memoized the argument already, or pairs has been
elseif metatable.donePairs or nilArgs[key] then
-- called, meaning that mergeArgs has already copied all of the
return nil
-- available arguments into the metaArgs table. We need to check for
-- pairs as we can't memoize nils to the metaArgs table while pairs
-- is iterating. Adding new instances of nilArg to the metaArgs
-- table while pairs is iterating over it produces undefined
-- behaviour in the next() function.
--]]
if val == nilArg then
return nil
else
return val
end
end
end
for _, argTable in ipairs(argTables) do
for _, argTable in ipairs(argTables) do
local argTableVal = tidyVal(key, argTable[key])
local argTableVal = tidyVal(key, argTable[key])
if argTableVal == nil then
if argTableVal ~= nil then
metaArgs[key] = nilArg
else
metaArgs[key] = argTableVal
metaArgs[key] = argTableVal
return argTableVal
return argTableVal
end
end
end
end
nilArgs[key] = 'h'
return nil
return nil
end
end


metatable.__newindex = function (t, key, val)
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
if options.readOnly then
error(
error(
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)
)
elseif val == nil then
elseif val == nil then
metaArgs[key] = nilArg -- Memoize nils.
--[[
-- 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
else
metaArgs[key] = val
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
end
end


metatable.__pairs = function ()
metatable.__pairs = function ()
-- Called when pairs is run on the args table.
if not metatable.donePairs then
if not metatable.donePairs then
mergeArgs(pairs, argTables)
mergeArgs(argTables)
metatable.donePairs = true
metatable.donePairs = true
metatable.doneIpairs = true
end
end
return function (t, k)
return translatenext, { t = metaArgs }
local nk, val = next(metaArgs, k)
end
if val == nilArg then
 
val = nil
local function inext(t, i)
end
-- This uses our __index metamethod
return nk, val
local v = t[i + 1]
if v ~= nil then
return i + 1, v
end
end
end
end


metatable.__ipairs = function ()
metatable.__ipairs = function (t)
if not metatable.doneIpairs then
-- Called when ipairs is run on the args table.
mergeArgs(ipairs, argTables)
return inext, t, 0
metatable.doneIpairs = true
end
return function (t, i)
local val = metaArgs[i + 1]
if val == nil then
return nil
elseif val == nilArg then
val = nil
end
return i + 1, val
end, nil, 0
end
end


Retrieved from "https://meta.skywiki.org/wiki/Module:Arguments"