Difference between revisions of "Module:Arguments"

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(allow using both the frame and parent frame arguments with the wrappers option if specifically requested, per protected edit request by User:Jackmcbarn)
 
m (1 revision)
 
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-- 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
 
 
-- We test for false specifically here so that nil (the default) acts like true.
 
if found or options.frameOnly == false then
 
pargs = parent.args
 
end
 
if not found or options.parentOnly == false then
 
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
 
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. 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
 

Latest revision as of 13:01, 17 July 2014

Documentation for this module may be created at Module:Arguments/doc