Module:Arguments: Difference between revisions
Jump to navigation
Jump to search
Content deleted Content added
fix undefined next() behaviour bug by checking for metatable.donePairs in the __index metamethod; also, format the module so it fits into 80 characters |
memoize nils using a separate nilArgs table; this fixes a bug where nil values were being iterated over with pairs() |
||
Line 7: | Line 7: | ||
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 |
||
Line 76: | Line 74: | ||
luaArgs = frame |
luaArgs = frame |
||
end |
end |
||
-- Set |
-- 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 |
local argTables = {fargs} |
||
⚫ | |||
⚫ | |||
⚫ | |||
--[[ |
--[[ |
||
Line 113: | Line 112: | ||
end |
end |
||
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 = {}, {}, {}, {} |
|||
⚫ | |||
local function mergeArgs(iterator, tables) |
local function mergeArgs(iterator, tables) |
||
Line 124: | Line 132: | ||
for _, t in ipairs(tables) do |
for _, t in ipairs(tables) do |
||
for key, val in iterator(t) do |
for key, val in iterator(t) do |
||
if metaArgs[key] == nil 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 |
||
nilArgs[key] = true |
|||
else |
else |
||
metaArgs[key] = tidiedVal |
metaArgs[key] = tidiedVal |
||
Line 136: | Line 143: | ||
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} |
|||
⚫ | |||
⚫ | |||
--[[ |
--[[ |
||
-- 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. |
-- and are only fetched from the argument tables once. Fetching arguments |
||
-- from the argument tables is the most resource-intensive step in this |
|||
-- also memoized using the nilArg variable in order to increase performance. |
|||
-- |
-- 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 |
|||
-- been called, so we do not run pairs and ipairs on fargs and pargs more |
|||
-- |
-- 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 |
|||
-- over. |
|||
-- 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. |
|||
--]] |
|||
local val = metaArgs[key] |
local val = metaArgs[key] |
||
if |
if val ~= nil then |
||
return val |
|||
elseif metatable.donePairs or nilArgs[key] then |
|||
-- We have either memoized the argument already, or pairs has been |
|||
⚫ | |||
-- 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 val |
|||
⚫ | |||
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 |
||
nilArgs[key] = true |
|||
else |
else |
||
metaArgs[key] = argTableVal |
metaArgs[key] = argTableVal |
||
Line 186: | Line 187: | ||
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 options.readOnly then |
if options.readOnly then |
||
error( |
error( |
||
Line 201: | Line 204: | ||
) |
) |
||
elseif val == nil then |
elseif val == nil then |
||
⚫ | |||
⚫ | |||
-- 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 |
|||
⚫ | |||
else |
else |
||
metaArgs[key] = val |
metaArgs[key] = val |
||
Line 208: | Line 219: | ||
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(pairs, argTables) |
||
Line 213: | Line 225: | ||
metatable.doneIpairs = true |
metatable.doneIpairs = true |
||
end |
end |
||
return |
return pairs(metaArgs) |
||
local nk, val = next(metaArgs, k) |
|||
if val == nilArg then |
|||
⚫ | |||
end |
|||
return nk, val |
|||
end |
|||
end |
end |
||
metatable.__ipairs = function () |
metatable.__ipairs = function () |
||
-- Called when ipairs is run on the args table. |
|||
if not metatable.doneIpairs then |
if not metatable.doneIpairs then |
||
mergeArgs(ipairs, argTables) |
mergeArgs(ipairs, argTables) |
||
metatable.doneIpairs = true |
metatable.doneIpairs = true |
||
end |
end |
||
return |
return ipairs(metaArgs) |
||
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 |
||