Module:Transclude

-- <nowiki>
--------------------------------------------------------------------------------
-- Module that allows transcluding a template with all parent arguments.
-- Useful in `/i18n` template subpages that delegate to a `/layout` subpage.
--
-- @module transclude
-- @author [[User:ExE Boss]]
--------------------------------------------------------------------------------

require('strict')
local checkType = require('libraryUtil').checkType;

local p = {}
local INVALID_TITLES = {
 ["."] = true,
 [".."] = true,
};

local function _ne(value)
 return value and value ~= ''
end

--------------------------------------------------------------------------------
-- Helper function that merges argument tables.
--
-- @function mergeArgs
-- @param {table} inArgs
-- @param {table} outArgs
--------------------------------------------------------------------------------
local function mergeArgs(inArgs, outArgs, opts)
 checkType("mergeArgs", 1, inArgs, "table");
 checkType("mergeArgs", 2, outArgs, "table");
 checkType("mergeArgs", 3, opts, "table", true);
 opts = opts or {}

 local ignoredParams = opts.ignoredParams;
 local ignoredPrefix = opts.ignoredPrefix;

 for name, value in pairs(inArgs) do
  if (type(name) == "string") then
   if not (
    (ignoredParams and ignoredParams[name] == true)
    or (ignoredPrefix and
     ignoredPrefix == name:sub(1, ignoredPrefix:len()))
   ) then
    outArgs[name] = value;
   end
  else
   outArgs[name] = value;
  end
 end

 return outArgs;
end

-- Exported for testing:
p['#mergeArgs'] = mergeArgs;

local mt = {};

function mt.__index(_, name)
 if (
  type(name) ~= "string"
  or INVALID_TITLES[name]
  or mw.ustring.find(name, "#", nil, true)
 ) then
  return nil;
 end

 local title = mw.title.new(name, "Template")
 if (not title) then
  return nil;
 end

 return function (frame)
  checkType('transclude["' .. name .. '"]', 1, frame, "table");
  local parentFrame = frame:getParent();

  local ignoredParams, ignoredPrefix;
  if _ne(frame.args["#ignoredParams"]) then
   ignoredParams = {};
            for m in mw.text.gsplit(frame.args["#ignoredParams"], '|', true) do
                ignoredParams[mw.text.trim(m)] = true;
            end
  end

  if _ne(frame.args['#ignoredPrefix']) then
   ignoredPrefix = frame.args['#ignoredPrefix'];
  end

  local args = {};
  if (parentFrame) then
   mergeArgs(parentFrame.args, args, {
    ignoredParams = ignoredParams,
    ignoredPrefix = ignoredPrefix,
   });
  end
  mergeArgs(frame.args, args, {
   ignoredPrefix = "#",
  });

  if (not title.exists) then
   return "[[:" .. title.fullText .. "]]";
  end

  return frame:expandTemplate{
   title = title,
   args = args,
  };
 end
end

return setmetatable(p, mt);