Module:Arguments/sandbox: Difference between revisions

Revision as of 08:01, 15 April 2014

Revision as of 20:10, 15 April 2014

Line 7:

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

Line 76 ⟶ 74:

luaArgs = frame

end

-- Set up the argsorder andof metaArgsprecedence tables.of argsthe willargument betables. theIf onethe accessedvariables fromare

-- functionsnil, and metaArgsnothing will holdbe added to the actualtable, which is how arguments.we Theavoid metatableclashes

-- connectsbetween the twoframe/parent togetherargs and the Lua args.

local args, metaArgs, metatableargTables = {}, {}, {fargs}

argTables[#argTables + 1] = pargs

setmetatable(args, metatable)

argTables[#argTables + 1] = luaArgs

--[[

Line 113 ⟶ 112:

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.

--]]

local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}

setmetatable(args, metatable)

local function mergeArgs(iterator, tables)

Line 124 ⟶ 132:

for _, t in ipairs(tables) do

for key, val in iterator(t) do

local metaArgsVal =if metaArgs[key] == nil then

if metaArgsVal == nil or metaArgsVal == nilArg then

local tidiedVal = tidyVal(key, val)

if tidiedVal == nil then

metaArgsnilArgs[key] = nilArgtrue

else

metaArgs[key] = tidiedVal

Line 136 ⟶ 143:

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,

-- and are only fetched from the argument tables once. Nil arguments are

-- also memoized using the nilArgnilArgs variabletable in order to increase performance.

-- 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

Line 157:

metatable.__index = function (t, key)

local val = metaArgs[key]

if metatable.donePairs or val ~= nil then

--[[return val

elseif val == nilArgnilArgs[key] then

-- We have either memoized the argument already, or pairs has been

return nil

-- called, meaning that mergeArgs has already copied all of the

-- 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

for _, argTable in ipairs(argTables) do

local argTableVal = tidyVal(key, argTable[key])

if argTableVal == nil then

metaArgsnilArgs[key] = nilArgtrue

else

metaArgs[key] = argTableVal

Line 201 ⟶ 190:

)

elseif val == nil then

metaArgsnilArgs[key] = nilArgtrue -- Memoize nils.

else

metaArgs[key] = val

Line 213 ⟶ 202:

metatable.doneIpairs = true

end

return function pairs(t, kmetaArgs)

local nk, val = next(metaArgs, k)

if val == nilArg then

val = nil

end

return nk, val

end

end

Line 227 ⟶ 210:

metatable.doneIpairs = true

end

return function ipairs(t, imetaArgs)

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