Module:Arguments: Difference between revisions

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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
    local function matchesTitle(given, title)
    local tp = type( given )
    return (tp == 'string' or tp == 'number') and mw.title.new( given ).prefixedText == title
    end
    local translate_mt = { __index = function(t, k) return k end }
    function arguments.getArgs(frame, options)
    checkType('getArgs', 1, frame, 'table', true)
    checkType('getArgs', 2, options, 'table', true)
    frame = frame or {}
    options = options or {}
    --[[
    -- Set up argument translation.
    --]]
    options.translate = options.translate or {}
    if getmetatable(options.translate) == nil then
    setmetatable(options.translate, translate_mt)
    end
    if options.backtranslate == nil then
    options.backtranslate = {}
    for k,v in pairs(options.translate) do
    options.backtranslate[v] = k
    end
    end
    if options.backtranslate and getmetatable(options.backtranslate) == nil then
    setmetatable(options.backtranslate, {
    __index = function(t, k)
    if options.translate[k] ~= k then
    return nil
    else
    return k
    end
    end
    })
    end
    --[[
    -- 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 matchesTitle(options.wrappers, title) then
    found = true
    elseif type(options.wrappers) == 'table' then
    for _,v in pairs(options.wrappers) do
    if matchesTitle(v, title) then
    found = true
    break
    end
    end
    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(tables)
    --[[
    -- Accepts multiple tables as input and merges their keys and values
    -- into one table. If a value is already present it is not overwritten;
    -- tables listed earlier have precedence. We are also memoizing nil
    -- values, which can be overwritten if they are 's' (soft).
    --]]
    for _, t in ipairs(tables) do
    for key, val in pairs(t) do
    if metaArgs[key] == nil and nilArgs[key] ~= 'h' then
    local tidiedVal = tidyVal(key, val)
    if tidiedVal == nil then
    nilArgs[key] = 's'
    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.
    --]]
    if type(key) == 'string' then
    key = options.translate[key]
    end
    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
    metaArgs[key] = argTableVal
    return argTableVal
    end
    end
    nilArgs[key] = 'h'
    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 type(key) == 'string' then
    key = options.translate[key]
    end
    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] = 'h'
    else
    metaArgs[key] = val
    end
    end
    local function translatenext(invariant)
    local k, v = next(invariant.t, invariant.k)
    invariant.k = k
    if k == nil then
    return nil
    elseif type(k) ~= 'string' or not options.backtranslate then
    return k, v
    else
    local backtranslate = options.backtranslate[k]
    if backtranslate == nil then
    -- Skip this one. This is a tail call, so this won't cause stack overflow
    return translatenext(invariant)
    else
    return backtranslate, v
    end
    end
    end
    metatable.__pairs = function ()
    -- Called when pairs is run on the args table.
    if not metatable.donePairs then
    mergeArgs(argTables)
    metatable.donePairs = true
    end
    return translatenext, { t = metaArgs }
    end
    local function inext(t, i)
    -- This uses our __index metamethod
    local v = t[i + 1]
    if v ~= nil then
    return i + 1, v
    end
    end
    metatable.__ipairs = function (t)
    -- Called when ipairs is run on the args table.
    return inext, t, 0
    end
    return args
    end
    return arguments

    Revision as of 17:13, 22 May 2016

    Documentation for this module may be created at Module:Arguments/doc
    Retrieved from "https://nonbinary.wiki/index.php?title=Module:Arguments&oldid=13081"