Difference between revisions of "Module:Arguments/sandbox"

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blackwiki>Mr. Stradivarius
(return an explicit nil from tidyVal)
blackwiki>Mr. Stradivarius
(memoize nil args)
Line 6: Line 6:
  
 
local arguments = {}
 
local arguments = {}
 +
 +
local nilArg = {} -- Used for memoizing nil arguments in metaArgs.
  
 
function arguments.getArgs(frame, options)
 
function arguments.getArgs(frame, options)
Line 60: Line 62:
 
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
+
local metaArgsVal = metaArgs[key]
metaArgs[key] = tidyVal(key, val)
+
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
Line 84: Line 92:
  
 
--[[
 
--[[
-- Define metatable behaviour. Arguments are stored in the metaArgs table, and are only fetched from the
+
-- Define metatable behaviour. Arguments are memoized in the metaArgs table, and are only fetched from the
-- argument tables once. Also, we keep a record in the metatable of when pairs and ipairs have been called,
+
-- argument tables once. Nil arguments are also memoized using the nilArg variable in order to increase
-- so we do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs
+
-- performance. Also, we keep a record in the metatable of when pairs and ipairs have been called, so we
-- and pargs if pairs has already been run, as all the arguments will already have been copied over.
+
-- 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)
 
metatable.__index = function (t, key)
 
local val = metaArgs[key]
 
local val = metaArgs[key]
 
if val ~= nil then
 
if val ~= nil then
return val
+
if val == nilArg then
 +
return nil
 +
else
 +
return val
 +
end
 
else
 
else
 
for i, argTable in ipairs(argTables) do
 
for i, 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
 +
return nil
 
end
 
end
 
end
 
end
Line 109: Line 125:
 
elseif options.noOverwrite and args[key] ~= nil then
 
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)
 
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
 
else
 
metaArgs[key] = val
 
metaArgs[key] = val

Revision as of 06:44, 11 December 2013

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
		fargs = frame.args
		pargs = frame:getParent().args
	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

	-- 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 = {}
	if options.frameOnly then
		table.insert(argTables, fargs)
	elseif options.parentOnly then
		table.insert(argTables, pargs)
	elseif options.parentFirst then
		table.insert(argTables, pargs)
		table.insert(argTables, fargs)
	else
		table.insert(argTables, fargs)
		table.insert(argTables, pargs)
	end
	table.insert(argTables, 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 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
		else
			for i, argTable in ipairs(argTables) do
				local argTableVal = tidyVal(key, argTable[key])
				if argTableVal == nil then
					metaArgs[key] = nilArg
				else
					metaArgs[key] = argTableVal
					return argTableVal
				end
			end
			return nil
		end
	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