Module:Arguments/sandbox
< Module:Arguments
Jump to navigation
Jump to search
Revision as of 07:27, 11 December 2013 by blackwiki>Mr. Stradivarius (start at replacing argTables - still need to convert mergeArgs though)
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 = {}
local nilArg = {} -- Used for memoizing nil arguments in metaArgs.
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 put the args in a special table 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 = type(frame) == 'table' and frame or {}
end
-- Set up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments.
-- The metatable connects the two together.
local args, metaArgs, metatable = {}, {}, {}
setmetatable(args, metatable)
local function tidyVal(key, val)
-- Processes a value according to the options given to getArguments. Can trim whitespace and remove blanks.
-- Keys are not used here, but they can be used by user-generated functions, so defining it here to avoid breakage.
if type(val) == 'string' then
if options.trim ~= false then
val = val:match('^%s*(.-)%s*$')
end
if options.removeBlanks == false or val:find('%S') then
return val
end
else
return val
end
return nil
end
-- Use a user-generated function to tidy the values if specified.
local valueFunc = options.valueFunc
if valueFunc then
local valueFuncType = type(valueFunc)
if valueFuncType == 'function' then
tidyVal = valueFunc
else
error('type error in option "valueFunc": expected function, got ' .. valueFuncType, 2)
end
end
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 precendence.
for _, t in ipairs(tables) do
for key, val in iterator(t) do
local metaArgsVal = metaArgs[key]
if metaArgsVal == nil or metaArgsVal == nilArg then
local tidiedVal = tidyVal(key, val)
if tidiedVal == nil then
metaArgs[key] = nilArg
else
metaArgs[key] = tidiedVal
end
end
end
end
end
local function getValAndMemoize(t, key)
-- Gets a value from an argument table and memoizes it in metaArgs.
if t then
local tidiedVal = tidyVal(key, t[key])
if tidiedVal == nil then
metaArgs[key] = nilArg
else
metaArgs[key] = tidiedVal
return tidiedVal
end
end
return nil
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 nilArg variable 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
if val == nilArg then
return nil
else
return val
end
end
local fargsVal = getValAndMemoize(fargs, key)
if fargsVal ~= nil then
return fargsVal
end
local pargsVal = getValAndMemoize(pargs, key)
if pargsVal ~= nil then
return pargsVal
end
local luaArgsVal = getValAndMemoize(luaArgs, key)
if luaArgsVal ~= nil then
return luaArgsVal
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] = nilArg -- 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