Difference between revisions of "Module:Arguments/sandbox"

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blackwiki>Mr. Stradivarius
(make the code fit within 80 characters)
blackwiki>Jackmcbarn
(memoize nils in a different way (unfortunately an edit conflict kept me from saving the line length changes))
Line 1: Line 1:
-- This module provides easy processing of arguments passed to Scribunto from
+
-- This module provides easy processing of arguments passed to Scribunto from #invoke.
-- #invoke. It is intended for use by other Lua modules, and should not be
+
-- It is intended for use by other Lua modules, and should not be called from #invoke directly.
-- called from #invoke directly.
 
  
 
local libraryUtil = require('libraryUtil')
 
local libraryUtil = require('libraryUtil')
Line 8: 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 options every time we call it.
 
 
-- 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)
 
local function tidyValDefault(key, val)
Line 56: Line 52:
 
options = options or {}
 
options = options or {}
  
--[[
+
-- Get the arguments from the frame object if available. If the frame object is not available, we are being called
-- Get the arguments from the frame object if available. If the frame object
+
-- from another Lua module or from the debug console, so assign the args to a new variable so we can differentiate them.
-- 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
 
local fargs, pargs, luaArgs
 
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
 
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
Line 77: Line 69:
 
end
 
end
  
-- Set up the args and metaArgs tables. args will be the one accessed from
+
-- Set up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments.
-- functions, and metaArgs will hold the actual arguments. The metatable
+
-- nilArgs contains keys of elements established to contain nil values. The metatable connects these together.
-- connects the two together.
+
local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}
local args, metaArgs, metatable = {}, {}, {}
 
 
setmetatable(args, metatable)
 
setmetatable(args, metatable)
  
--[[
+
-- Generate the tidyVal function. If it has been specified by the user, we use that; if not, we choose one of four functions
-- Generate the tidyVal function. If it has been specified by the user, we
+
-- depending on the options chosen. This is so that we don't have to call the options table every time the function is called.
-- 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
 
local tidyVal = options.valueFunc
 
if tidyVal then
 
if tidyVal then
 
if type(tidyVal) ~= 'function' then
 
if type(tidyVal) ~= 'function' then
error(
+
error("bad value assigned to option 'valueFunc' (function expected, got " .. type(tidyVal) .. ')', 2)
"bad value assigned to option 'valueFunc'"
 
.. '(function expected, got '
 
.. type(tidyVal)
 
.. ')',
 
2
 
)
 
 
end
 
end
 
elseif options.trim ~= false then
 
elseif options.trim ~= false then
Line 115: Line 96:
  
 
local function mergeArgs(iterator, tables)
 
local function mergeArgs(iterator, tables)
--[[
+
-- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator.
-- Accepts multiple tables as input and merges their keys and values
+
-- If a value is already present it is not overwritten; tables listed earlier have precedence.
-- into one table using the specified iterator. If a value is already
+
-- We are also memoizing nil values, but those values can be overwritten.
-- 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 _, t in ipairs(tables) do
 
for key, val in iterator(t) do
 
for key, val in iterator(t) do
local metaArgsVal = metaArgs[key]
+
if not nilArgs[key] then
if metaArgsVal == nil or metaArgsVal == nilArg then
+
local metaArgsVal = metaArgs[key]
local tidiedVal = tidyVal(key, val)
+
if metaArgsVal == nil then
if tidiedVal == nil then
+
local tidiedVal = tidyVal(key, val)
metaArgs[key] = nilArg
+
if tidiedVal == nil then
else
+
nilArgs[key] = true
metaArgs[key] = tidiedVal
+
else
 +
metaArgs[key] = tidiedVal
 +
end
 
end
 
end
 
end
 
end
Line 137: Line 116:
 
end
 
end
  
-- Set the order of precedence of the argument tables. If the variables are
+
-- Set the order of precedence of the argument tables. If the variables are nil, nothing will be added to the table,
-- nil, nothing will be added to the table, which is how we avoid clashes
+
-- which is how we avoid clashes between the frame/parent args and the Lua args.
-- between the frame/parent args and the Lua args.
 
 
local argTables = {fargs}
 
local argTables = {fargs}
 
argTables[#argTables + 1] = pargs
 
argTables[#argTables + 1] = pargs
Line 145: Line 123:
  
 
--[[
 
--[[
-- 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
-- and are only fetched from the argument tables once. Nil arguments are
+
-- argument tables once. Nil arguments are also memoized using the nilArg variable in order to increase
-- also memoized using the nilArg variable in order to increase performance.
+
-- performance. Also, we keep a record in the metatable of when pairs and ipairs have been called, so we
-- Also, we keep a record in the metatable of when pairs and ipairs have
+
-- do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs and
-- been called, so we do not run pairs and ipairs on fargs and pargs more
+
-- pargs if pairs has already been run, as all the arguments will already have been copied over.
-- 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)
 +
if nilArgs[key] then
 +
return nil
 +
end
 
local val = metaArgs[key]
 
local val = metaArgs[key]
 
if val ~= nil then
 
if val ~= nil then
if val == nilArg then
+
return val
return nil
 
else
 
return val
 
end
 
 
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
if not metatable.donePairs then
+
nilArgs[key] = true
--[[
 
-- Memoize nils, but not if pairs has been used on the args
 
-- table. The pairs check is to avoid the possibility of
 
-- adding new entries to the table during the pairs
 
-- iteration, as this produces undefined behaviour in the
 
-- next() function.
 
--]]
 
metaArgs[key] = nilArg
 
end
 
 
else
 
else
 
metaArgs[key] = argTableVal
 
metaArgs[key] = argTableVal
Line 187: Line 152:
 
metatable.__newindex = function (t, key, val)
 
metatable.__newindex = function (t, key, val)
 
if options.readOnly then
 
if options.readOnly then
error(
+
error('could not write to argument table key "' .. tostring(key) .. '"; the table is read-only', 2)
'could not write to argument table key "'
+
elseif options.noOverwrite and (args[key] ~= nil or nilArgs[key]) then
.. tostring(key)
+
error('could not write to argument table key "' .. tostring(key) .. '"; overwriting existing arguments is not permitted', 2)
.. '"; 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
 
elseif val == nil then
metaArgs[key] = nilArg -- Memoize nils.
+
-- Memoize nils.
 +
nilArgs[key] = true
 +
metaArgs[key] = nil
 
else
 
else
 +
nilArgs[key] = nil
 
metaArgs[key] = val
 
metaArgs[key] = val
 
end
 
end
Line 214: Line 172:
 
end
 
end
 
return function (t, k)
 
return function (t, k)
local nk, val = next(metaArgs, k)
+
return next(metaArgs, k)
if val == nilArg then
 
val = nil
 
end
 
return nk, val
 
 
end
 
end
 
end
 
end
Line 228: Line 182:
 
end
 
end
 
return function (t, i)
 
return function (t, i)
 +
if nilArgs[i + 1] then
 +
return nil
 +
end
 
local val = metaArgs[i + 1]
 
local val = metaArgs[i + 1]
 
if val == nil then
 
if val == nil then
 
return nil
 
return nil
elseif val == nilArg then
 
val = nil
 
 
end
 
end
 
return i + 1, val
 
return i + 1, val

Revision as of 23:12, 13 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 up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments.
	-- nilArgs contains keys of elements established to contain nil values. The metatable connects these together.
	local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}
	setmetatable(args, metatable)

	-- 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

	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 not nilArgs[key] then
					local metaArgsVal = metaArgs[key]
					if metaArgsVal == nil then
						local tidiedVal = tidyVal(key, val)
						if tidiedVal == nil then
							nilArgs[key] = true
						else
							metaArgs[key] = tidiedVal
						end
					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 = {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 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)
		if nilArgs[key] then
			return nil
		end
		local val = metaArgs[key]
		if val ~= nil then
			return val
		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 or nilArgs[key]) then
			error('could not write to argument table key "' .. tostring(key) .. '"; overwriting existing arguments is not permitted', 2)
		elseif val == nil then
			-- Memoize nils.
			nilArgs[key] = true
			metaArgs[key] = nil
		else
			nilArgs[key] = nil
			metaArgs[key] = val
		end
	end

	metatable.__pairs = function ()
		if not metatable.donePairs then
			mergeArgs(pairs, argTables)
			metatable.donePairs = true
			metatable.doneIpairs = true
		end
		return function (t, k)
			return next(metaArgs, k)
		end
	end

	metatable.__ipairs = function ()
		if not metatable.doneIpairs then
			mergeArgs(ipairs, argTables)
			metatable.doneIpairs = true
		end
		return function (t, i)
			if nilArgs[i + 1] then
				return nil
			end
			local val = metaArgs[i + 1]
			if val == nil then
				return nil
			end
			return i + 1, val
		end, nil, 0
	end

	return args
end

return arguments