Module:Arguments: Difference between revisions
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m (tweak one of the comments and make some beautification fixes, now that this is in the job queue) |
(fix undefined next() behaviour bug by checking for metatable.donePairs in the __index metamethod; also, format the module so it fits into 80 characters) |
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-- This module provides easy processing of arguments passed to Scribunto from |
-- This module provides easy processing of arguments passed to Scribunto from |
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-- 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 |
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-- called from #invoke directly. |
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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. |
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-- 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 |
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-- options every time we call it. |
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local function tidyValDefault(key, val) |
local function tidyValDefault(key, val) |
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options = options or {} |
options = options or {} |
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--[[ |
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-- Get the arguments from the frame object if available. If the frame object |
-- Get the arguments from the frame object if available. If the frame object |
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⚫ | |||
-- is not available, we are being called from another Lua module or from the |
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⚫ | |||
-- differentiate them. |
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--]] |
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local fargs, pargs, luaArgs |
local fargs, pargs, luaArgs |
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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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Line 71: | Line 77: | ||
end |
end |
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-- 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 |
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-- functions, and metaArgs will hold the actual arguments. The metatable |
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-- |
-- connects the two together. |
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local args, metaArgs, metatable = {}, {}, {} |
local args, metaArgs, metatable = {}, {}, {} |
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setmetatable(args, metatable) |
setmetatable(args, metatable) |
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--[[ |
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-- 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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⚫ | |||
-- use that; if not, we choose one of four functions depending on the |
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⚫ | |||
-- every time the function is called. |
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--]] |
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local tidyVal = options.valueFunc |
local tidyVal = options.valueFunc |
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if tidyVal then |
if tidyVal then |
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if type(tidyVal) ~= 'function' then |
if type(tidyVal) ~= 'function' then |
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error( |
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"bad value assigned to option 'valueFunc'" |
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.. '(function expected, got ' |
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.. type(tidyVal) |
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.. ')', |
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2 |
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) |
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end |
end |
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elseif options.trim ~= false then |
elseif options.trim ~= false then |
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local function mergeArgs(iterator, tables) |
local function mergeArgs(iterator, tables) |
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--[[ |
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-- Accepts multiple tables as input and merges their keys and values |
-- Accepts multiple tables as input and merges their keys and values |
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⚫ | |||
-- into one table using the specified iterator. If a value is already |
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⚫ | |||
⚫ | |||
⚫ | |||
-- overwritten. |
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--]] |
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for _, t in ipairs(tables) do |
for _, t in ipairs(tables) do |
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for key, val in iterator(t) do |
for key, val in iterator(t) do |
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Line 116: | Line 137: | ||
end |
end |
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-- 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 |
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-- nil, nothing will be added to the table, which is how we avoid clashes |
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-- |
-- between the frame/parent args and the Lua args. |
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local argTables = {fargs} |
local argTables = {fargs} |
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argTables[#argTables + 1] = pargs |
argTables[#argTables + 1] = pargs |
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--[[ |
--[[ |
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-- Define metatable behaviour. Arguments are memoized in the metaArgs table, |
-- Define metatable behaviour. Arguments are memoized in the metaArgs table, |
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-- and are only fetched from the argument tables once. Nil arguments are |
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-- |
-- also memoized using the nilArg variable in order to increase performance. |
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-- |
-- Also, we keep a record in the metatable of when pairs and ipairs have |
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-- do not run pairs and ipairs on fargs and pargs more |
-- been called, so we do not run pairs and ipairs on fargs and pargs more |
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⚫ | |||
-- than once. We also do not run ipairs on fargs and pargs if pairs has |
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⚫ | |||
-- over. |
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--]] |
--]] |
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metatable.__index = function (t, key) |
metatable.__index = function (t, key) |
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local val = metaArgs[key] |
local val = metaArgs[key] |
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if val ~= nil then |
if metatable.donePairs or val ~= nil then |
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--[[ |
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-- We have either memoized the argument already, or pairs has been |
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-- called, meaning that mergeArgs has already copied all of the |
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-- available arguments into the metaArgs table. We need to check for |
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-- pairs as we can't memoize nils to the metaArgs table while pairs |
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-- is iterating. Adding new instances of nilArg to the metaArgs |
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-- table while pairs is iterating over it produces undefined |
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-- behaviour in the next() function. |
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--]] |
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if val == nilArg then |
if val == nilArg then |
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return nil |
return nil |
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Line 153: | Line 187: | ||
metatable.__newindex = function (t, key, val) |
metatable.__newindex = function (t, key, val) |
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if options.readOnly then |
if options.readOnly then |
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error( |
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'could not write to argument table key "' |
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.. tostring(key) |
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.. '"; the table is read-only', |
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2 |
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) |
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elseif options.noOverwrite and args[key] ~= nil then |
elseif options.noOverwrite and args[key] ~= nil then |
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error( |
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⚫ | |||
'could not write to argument table key "' |
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.. tostring(key) |
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⚫ | |||
2 |
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) |
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elseif val == nil then |
elseif val == nil then |
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metaArgs[key] = nilArg -- Memoize nils. |
metaArgs[key] = nilArg -- Memoize nils. |