Module:Arguments: Difference between revisions

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Module:Arguments (view source)

Revision as of 09:35, 16 April 2014

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-- This module provides easy processing of arguments passed to Scribunto from #invoke.
-- This module provides easy processing of arguments passed to Scribunto from
-- It is intended for use by other Lua modules, and should not be called from #invoke directly.
-- #invoke. It is intended for use by other Lua modules, and should not be
-- called from #invoke directly.


local libraryUtil = require('libraryUtil')
local libraryUtil = require('libraryUtil')
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local nilArg = {} -- Used for memoizing nil arguments in metaArgs.
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)
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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
--[[
-- from another Lua module or from the debug console, so assign the args to a new variable so we can differentiate them.
-- 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
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
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end
end


-- Set up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments.
-- Set up the args and metaArgs tables. args will be the one accessed from
-- The metatable connects the two together.
-- functions, and metaArgs will hold the actual arguments. The metatable
-- connects the two together.
local args, metaArgs, 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
--[[
-- depending on the options chosen. This is so that we don't have to call the options table every time the function is called.
-- 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
local tidyVal = options.valueFunc
if tidyVal then
if tidyVal then
if type(tidyVal) ~= 'function' then
if type(tidyVal) ~= 'function' then
error("bad value assigned to option 'valueFunc' (function expected, got " .. type(tidyVal) .. ')', 2)
error(
"bad value assigned to option 'valueFunc'"
.. '(function expected, got '
.. type(tidyVal)
.. ')',
2
)
end
end
elseif options.trim ~= false then
elseif options.trim ~= false then
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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.
--[[
-- If a value is already present it is not overwritten; tables listed earlier have precedence.
-- Accepts multiple tables as input and merges their keys and values
-- We are also memoizing nil values, but those values can be overwritten.
-- 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 _, t in ipairs(tables) do
for key, val in iterator(t) do
for key, val in iterator(t) do
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end
end


-- Set the order of precedence of the argument tables. If the variables are nil, nothing will be added to the table,
-- Set the order of precedence of the argument tables. If the variables are
-- which is how we avoid clashes between the frame/parent args and the Lua args.
-- 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}
local argTables = {fargs}
argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = pargs
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--[[
--[[
-- Define metatable behaviour. Arguments are memoized in the metaArgs table, and are only fetched from the
-- Define metatable behaviour. Arguments are memoized in the metaArgs table,
-- argument tables once. Nil arguments are also memoized using the nilArg variable in order to increase
-- and are only fetched from the argument tables once. Nil arguments are
-- performance. Also, we keep a record in the metatable of when pairs and ipairs have been called, so we
-- also memoized using the nilArg variable in order to increase performance.
-- do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs and
-- Also, we keep a record in the metatable of when pairs and ipairs have
-- pargs if pairs has already been run, as all the arguments will already have been copied over.
-- 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)
metatable.__index = function (t, key)
local val = metaArgs[key]
local val = metaArgs[key]
if val ~= nil then
if metatable.donePairs or val ~= nil then
--[[
-- We have either memoized the argument already, or pairs has been
-- called, meaning that mergeArgs has already copied all of the
-- available arguments into the metaArgs table. We need to check for
-- pairs as we can't memoize nils to the metaArgs table while pairs
-- is iterating. Adding new instances of nilArg to the metaArgs
-- table while pairs is iterating over it produces undefined
-- behaviour in the next() function.
--]]
if val == nilArg then
if val == nilArg then
return nil
return nil
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metatable.__newindex = function (t, key, val)
metatable.__newindex = function (t, key, val)
if options.readOnly then
if options.readOnly then
error('could not write to argument table key "' .. tostring(key) .. '"; the table is read-only', 2)
error(
'could not write to argument table key "'
.. tostring(key)
.. '"; the table is read-only',
2
)
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
elseif val == nil then
metaArgs[key] = nilArg -- Memoize nils.
metaArgs[key] = nilArg -- Memoize nils.
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