Difference between revisions of "Module:Arguments/sandbox"
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blackwiki>Mr. Stradivarius (memoize nils to a separate nilArgs table) |
blackwiki>Mr. Stradivarius (allow __newindex to overwrite values in the metaArgs table with nil) |
||
Line 190: | Line 190: | ||
) | ) | ||
elseif val == nil then | elseif val == nil then | ||
+ | metaArgs[key] = nil | ||
nilArgs[key] = true -- Memoize nils. | nilArgs[key] = true -- Memoize nils. | ||
else | else |
Revision as of 21:09, 15 April 2014
Documentation for this module may be created at Module:Arguments/sandbox/doc
-- 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.
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local arguments = {}
-- Generate four different tidyVal functions, so that we don't have to check the
-- options every time we call it.
local function tidyValDefault(key, val)
if type(val) == 'string' then
val = val:match('^%s*(.-)%s*$')
if val == '' then
return nil
else
return val
end
else
return val
end
end
local function tidyValTrimOnly(key, val)
if type(val) == 'string' then
return val:match('^%s*(.-)%s*$')
else
return val
end
end
local function tidyValRemoveBlanksOnly(key, val)
if type(val) == 'string' then
if val:find('%S') then
return val
else
return nil
end
else
return val
end
end
local function tidyValNoChange(key, val)
return val
end
function arguments.getArgs(frame, options)
checkType('getArgs', 1, frame, 'table', true)
checkType('getArgs', 2, options, 'table', true)
frame = frame or {}
options = options or {}
--[[
-- Get the arguments from the frame object if available. If the frame object
-- 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
-- differentiate them.
--]]
local fargs, pargs, luaArgs
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
if not options.parentOnly then
fargs = frame.args
end
if not options.frameOnly then
pargs = frame:getParent().args
end
if options.parentFirst then
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.
local argTables = {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.
--]]
local tidyVal = options.valueFunc
if tidyVal then
if type(tidyVal) ~= 'function' then
error(
"bad value assigned to option 'valueFunc'"
.. '(function expected, got '
.. type(tidyVal)
.. ')',
2
)
end
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 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)
--[[
-- Accepts multiple tables as input and merges their keys and values
-- into one table using the specified iterator. If a value is already
-- present it is not overwritten; tables listed earlier have precedence.
-- We are also memoizing nil values, but those values can be
-- overwritten.
--]]
for _, t in ipairs(tables) do
for key, val in iterator(t) do
if metaArgs[key] == nil then
local tidiedVal = tidyVal(key, val)
if tidiedVal == nil then
nilArgs[key] = true
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. Nil arguments are
-- also memoized using the nilArgs table 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
-- 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)
local val = metaArgs[key]
if val ~= nil then
return val
elseif nilArgs[key] then
return nil
end
for _, argTable in ipairs(argTables) do
local argTableVal = tidyVal(key, argTable[key])
if argTableVal == nil then
nilArgs[key] = true
else
metaArgs[key] = argTableVal
return argTableVal
end
end
return nil
end
metatable.__newindex = function (t, key, val)
if options.readOnly then
error(
'could not write to argument table key "'
.. tostring(key)
.. '"; the table is read-only',
2
)
elseif options.noOverwrite and args[key] ~= nil then
error(
'could not write to argument table key "'
.. tostring(key)
.. '"; overwriting existing arguments is not permitted',
2
)
elseif val == nil then
metaArgs[key] = nil
nilArgs[key] = true -- Memoize nils.
else
metaArgs[key] = val
end
end
metatable.__pairs = function ()
if not metatable.donePairs then
mergeArgs(pairs, argTables)
metatable.donePairs = true
metatable.doneIpairs = true
end
return pairs(metaArgs)
end
metatable.__ipairs = function ()
if not metatable.doneIpairs then
mergeArgs(ipairs, argTables)
metatable.doneIpairs = true
end
return ipairs(metaArgs)
end
return args
end
return arguments