Difference between revisions of "Module:Arguments"

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en>Mr. Stradivarius
(add a "wrappers" option and fix bug when frame:getParent() returns nil, per protected edit request by User:Jackmcbarn)
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-- #invoke. It is intended for use by other Lua modules, and should not be
-- #invoke. 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')
local checkType = libraryUtil.checkType
local checkType = libraryUtil.checkType
 
local arguments = {}
local arguments = {}
 
-- 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
-- options every time we call it.
-- options every time we call it.
 
local function tidyValDefault(key, val)
local function tidyValDefault(key, val)
if type(val) == 'string' then
if type(val) == 'string' then
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end
end
end
end
 
local function tidyValTrimOnly(key, val)
local function tidyValTrimOnly(key, val)
if type(val) == 'string' then
if type(val) == 'string' then
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end
end
end
end
 
local function tidyValRemoveBlanksOnly(key, val)
local function tidyValRemoveBlanksOnly(key, val)
if type(val) == 'string' then
if type(val) == 'string' then
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end
end
end
end
 
local function tidyValNoChange(key, val)
local function tidyValNoChange(key, val)
return val
return val
end
end
 
function arguments.getArgs(frame, options)
function arguments.getArgs(frame, options)
checkType('getArgs', 1, frame, 'table', true)
checkType('getArgs', 1, frame, 'table', true)
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frame = frame or {}
frame = frame or {}
options = options or {}
options = options or {}
 
--[[
--[[
-- Get the arguments from the frame object if available. If the frame object
-- Get the argument tables. If we were passed a valid frame object, get the
-- is not available, we are being called from another Lua module or from the
-- frame arguments (fargs) and the parent frame arguments (pargs), depending
-- debug console, so assign the args to a new variable so we can
-- on the options set and on the parent frame's availability. If we weren't
-- differentiate them.
-- passed a valid frame object, we are being called from another Lua module
-- or from the debug console, so assume that we were passed a table of args
-- directly, and assign it to a new variable (luaArgs).
--]]
--]]
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
if not options.parentOnly then
if options.wrappers then
fargs = frame.args
--[[
end
-- The wrappers option makes Module:Arguments look up arguments in
if not options.frameOnly then
-- either the frame argument table or the parent argument table, but
pargs = frame:getParent().args
-- not both. This means that users can use either the #invoke syntax
end
-- or a wrapper template without the loss of performance associated
if options.parentFirst then
-- with looking arguments up in both the frame and the parent frame.
fargs, pargs = pargs, fargs
-- Module:Arguments will look up arguments in the parent frame
-- if it finds the parent frame's title in options.wrapper;
-- otherwise it will look up arguments in the frame object passed
-- to getArgs.
--]]
local parent = frame:getParent()
if not parent then
fargs = frame.args
else
local title = parent:getTitle():gsub('/sandbox$', '')
local found = false
if type(options.wrappers) == 'table' then
for _,v in pairs(options.wrappers) do
if v == title then
found = true
break
end
end
elseif options.wrappers == title then
found = true
end
if found then
pargs = parent.args
else
fargs = frame.args
end
end
else
-- options.wrapper isn't set, so check the other options.
if not options.parentOnly then
fargs = frame.args
end
if not options.frameOnly then
local parent = frame:getParent()
pargs = parent and parent.args or nil
end
if options.parentFirst then
fargs, pargs = pargs, fargs
end
end
end
else
else
luaArgs = frame
luaArgs = frame
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, which is how we avoid clashes
-- nil, nothing will be added to the table, which is how we avoid clashes
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argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = luaArgs
argTables[#argTables + 1] = luaArgs
 
--[[
--[[
-- Generate the tidyVal function. If it has been specified by the user, we
-- Generate the tidyVal function. If it has been specified by the user, we
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end
end
end
end
 
--[[
--[[
-- Set up the args, metaArgs and nilArgs tables. args will be the one
-- Set up the args, metaArgs and nilArgs tables. args will be the one
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local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}
local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}
setmetatable(args, metatable)
setmetatable(args, metatable)
 
local function mergeArgs(iterator, tables)
local function mergeArgs(iterator, tables)
--[[
--[[
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end
end
end
end
 
--[[
--[[
-- Define metatable behaviour. Arguments are memoized in the metaArgs table,
-- Define metatable behaviour. Arguments are memoized in the metaArgs table,
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-- the arguments will already have been copied over.
-- the arguments will already have been copied over.
--]]
--]]
 
metatable.__index = function (t, key)
metatable.__index = function (t, key)
--[[
--[[
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return nil
return nil
end
end
 
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
-- This function is called when a module tries to add a new value to the
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--]]
--]]
metaArgs[key] = nil
metaArgs[key] = nil
nilArgs[key] = true -- Memoize nils.
nilArgs[key] = true
else
else
metaArgs[key] = val
metaArgs[key] = val
end
end
end
end
 
metatable.__pairs = function ()
metatable.__pairs = function ()
-- Called when pairs is run on the args table.
-- Called when pairs is run on the args table.
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return pairs(metaArgs)
return pairs(metaArgs)
end
end
 
metatable.__ipairs = function ()
metatable.__ipairs = function ()
-- Called when ipairs is run on the args table.
-- Called when ipairs is run on the args table.
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return ipairs(metaArgs)
return ipairs(metaArgs)
end
end
 
return args
return args
end
end
 
return arguments
return arguments

Revision as of 14:24, 6 June 2014

Documentation for this module may be created at Module:Arguments/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 argument tables. If we were passed a valid frame object, get the
	-- frame arguments (fargs) and the parent frame arguments (pargs), depending
	-- on the options set and on the parent frame's availability. If we weren't
	-- passed a valid frame object, we are being called from another Lua module
	-- or from the debug console, so assume that we were passed a table of args
	-- directly, and assign it to a new variable (luaArgs).
	--]]
	local fargs, pargs, luaArgs
	if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
		if options.wrappers then
			--[[
			-- The wrappers option makes Module:Arguments look up arguments in
			-- either the frame argument table or the parent argument table, but
			-- not both. This means that users can use either the #invoke syntax
			-- or a wrapper template without the loss of performance associated
			-- with looking arguments up in both the frame and the parent frame.
			-- Module:Arguments will look up arguments in the parent frame
			-- if it finds the parent frame's title in options.wrapper;
			-- otherwise it will look up arguments in the frame object passed
			-- to getArgs.
			--]]
			local parent = frame:getParent()
			if not parent then
				fargs = frame.args
			else
				local title = parent:getTitle():gsub('/sandbox$', '')
				local found = false
				if type(options.wrappers) == 'table' then
					for _,v in pairs(options.wrappers) do
						if v == title then
							found = true
							break
						end
					end
				elseif options.wrappers == title then
					found = true
				end
				if found then
					pargs = parent.args
				else
					fargs = frame.args
				end
			end
		else
			-- options.wrapper isn't set, so check the other options.
			if not options.parentOnly then
				fargs = frame.args
			end
			if not options.frameOnly then
				local parent = frame:getParent()
				pargs = parent and parent.args or nil
			end
			if options.parentFirst then
				fargs, pargs = pargs, fargs
			end
		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. Fetching arguments
	-- from the argument tables is the most resource-intensive step in this
	-- 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
	-- 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
	-- the arguments will already have been copied over.
	--]]

	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]
		if val ~= nil then
			return val
		elseif metatable.donePairs or 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)
		-- 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
			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
			--[[
			-- 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
			nilArgs[key] = true
		else
			metaArgs[key] = val
		end
	end

	metatable.__pairs = function ()
		-- Called when pairs is run on the args table.
		if not metatable.donePairs then
			mergeArgs(pairs, argTables)
			metatable.donePairs = true
			metatable.doneIpairs = true
		end
		return pairs(metaArgs)
	end

	metatable.__ipairs = function ()
		-- Called when ipairs is run on the args table.
		if not metatable.doneIpairs then
			mergeArgs(ipairs, argTables)
			metatable.doneIpairs = true
		end
		return ipairs(metaArgs)
	end

	return args
end

return arguments