Module:Italic title

This Lua module is used on approximately 1,120,000 pages, or roughly 6048% of all pages.
To avoid major disruption and server load, any changes should be tested in the module's /sandbox or /testcases subpages, or in your own module sandbox. The tested changes can be added to this page in a single edit. Consider discussing changes on the talk page before implementing them.
File:Full-protection-shackle.svg
This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing.
This module depends on the following other modules:
This module implements {{italic title}} and {{italic dab}}. Please see the template pages for documentation.
-- This module implements {{italic title}}.

require('strict')
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkTypeForNamedArg = libraryUtil.checkTypeForNamedArg
local yesno = require('Module:Yesno')

--------------------------------------------------------------------------------
-- ItalicTitle class
--------------------------------------------------------------------------------

local ItalicTitle = {}

do
	----------------------------------------------------------------------------
	-- Class attributes and functions
	-- Things that belong to the class are here. Things that belong to each
	-- object are in the constructor.
	----------------------------------------------------------------------------

	-- Keys of title parts that can be italicized.
	local italicizableKeys = {
		namespace = true,
		title = true,
		dab = true,
	}

	----------------------------------------------------------------------------
	-- ItalicTitle constructor
	-- This contains all the dynamic attributes and methods.
	----------------------------------------------------------------------------

	function ItalicTitle.new()
		local obj = {}

		-- Function for checking self variable in methods.
		local checkSelf = libraryUtil.makeCheckSelfFunction(
			'ItalicTitle',
			'obj',
			obj,
			'ItalicTitle object'
		)

		-- Checks a key is present in a lookup table.
		-- Param: name - the function name.
		-- Param: argId - integer position of the key in the argument list.
		-- Param: key - the key.
		-- Param: lookupTable - the table to look the key up in.
		local function checkKey(name, argId, key, lookupTable)
			if not lookupTable[key] then
				error(string.format(
					"bad argument #%d to '%s' ('%s' is not a valid key)",
					argId,
					name,
					key
				), 3)
			end
		end

		-- Set up object structure.
		local parsed = false
		local categories = {}
		local italicizedKeys = {}
		local italicizedSubstrings = {}

		-- Parses a title object into its namespace text, title, and
		-- disambiguation text.
		-- Param: options - a table of options with the following keys:
		--     title - the title object to parse
		--     ignoreDab - ignore any disambiguation parentheses
		-- Returns the current object.
		function obj:parseTitle(options)
			checkSelf(self, 'parseTitle')
			checkType('parseTitle', 1, options, 'table')
			checkTypeForNamedArg('parseTitle', 'title', options.title, 'table')
			local title = options.title
		
			-- Title and dab text
			local prefix, parentheses
			if not options.ignoreDab then
				prefix, parentheses = mw.ustring.match(
					title.text,
					'^(.+) %(([^%(%)]+)%)$'
				)
			end
			if prefix and parentheses then
				self.title = prefix
				self.dab = parentheses
			else
				self.title = title.text
			end
		
			-- Namespace
			local namespace = mw.site.namespaces[title.namespace].name
			if namespace and #namespace >= 1 then
				self.namespace = namespace
			end

			-- Register the object as having parsed a title.
			parsed = true
		
			return self
		end

		-- Italicizes part of the title.
		-- Param: key - the key of the title part to be italicized. Possible
		-- keys are contained in the italicizableKeys table.
		-- Returns the current object.
		function obj:italicize(key)
			checkSelf(self, 'italicize')
			checkType('italicize', 1, key, 'string')
			checkKey('italicize', 1, key, italicizableKeys)
			italicizedKeys[key] = true
			return self
		end

		-- Un-italicizes part of the title.
		-- Param: key - the key of the title part to be un-italicized. Possible
		-- keys are contained in the italicizableKeys table.
		-- Returns the current object.
		function obj:unitalicize(key)
			checkSelf(self, 'unitalicize')
			checkType('unitalicize', 1, key, 'string')
			checkKey('unitalicize', 1, key, italicizableKeys)
			italicizedKeys[key] = nil
			return self
		end

		-- Italicizes a substring in the title. This only affects the main part
		-- of the title, not the namespace or the disambiguation text.
		-- Param: s - the substring to be italicized.
		-- Returns the current object.
		function obj:italicizeSubstring(s)
			checkSelf(self, 'italicizeSubstring')
			checkType('italicizeSubstring', 1, s, 'string')
			italicizedSubstrings[s] = true
			return self
		end

		-- Un-italicizes a substring in the title. This only affects the main
		-- part of the title, not the namespace or the disambiguation text.
		-- Param: s - the substring to be un-italicized.
		-- Returns the current object.
		function obj:unitalicizeSubstring(s)
			checkSelf(self, 'unitalicizeSubstring')
			checkType('unitalicizeSubstring', 1, s, 'string')
			italicizedSubstrings[s] = nil
			return self
		end

		-- Renders the object into a page name. If no title has yet been parsed,
		-- the current title is used.
		-- Returns string
		function obj:renderTitle()
			checkSelf(self, 'renderTitle')

			-- Italicizes a string
			-- Param: s - the string to italicize
			-- Returns string.
			local function italicize(s)
				assert(type(s) == 'string', 's was not a string')
				assert(s ~= '', 's was the empty string')
				return string.format('<i>%s</i>', s)
			end
		
			-- Escape characters in a string that are magic in Lua patterns.
			-- Param: pattern - the pattern to escape
			-- Returns string.
			local function escapeMagicCharacters(s)
				assert(type(s) == 'string', 's was not a string')
				return s:gsub('%p', '%%%0')
			end

			-- If a title hasn't been parsed yet, parse the current title.
			if not parsed then
				self:parseTitle{title = mw.title.getCurrentTitle()}
			end

			-- Italicize the different parts of the title and store them in a
			-- titleParts table to be joined together later.
			local titleParts = {}

			-- Italicize the italicizable keys.
			for key in pairs(italicizableKeys) do
				if self[key] then
					if italicizedKeys[key] then
						titleParts[key] = italicize(self[key])
					else
						titleParts[key] = self[key]
					end
				end
			end

			-- Italicize substrings. If there are any substrings to be
			-- italicized then start from the raw title, as this overrides any
			-- italicization of the main part of the title.
			if next(italicizedSubstrings) then
				titleParts.title = self.title
				for s in pairs(italicizedSubstrings) do
					local pattern = escapeMagicCharacters(s)
					local italicizedTitle, nReplacements = titleParts.title:gsub(
						pattern,
						italicize
					)
					titleParts.title = italicizedTitle

					-- If we didn't make any replacements then it means that we
					-- have been passed a bad substring or that the page has
					-- been moved to a bad title, so add a tracking category.
					if nReplacements < 1 then
						categories['Pages using italic title with no matching string'] = true
					end
				end
			end

			-- Assemble the title together from the parts.
			local ret = ''
			if titleParts.namespace then
				ret = ret .. titleParts.namespace .. ':'
			end
			ret = ret .. titleParts.title
			if titleParts.dab then
				ret = ret .. ' (' .. titleParts.dab .. ')'
			end

			return ret
		end

		-- Returns an expanded DISPLAYTITLE parser function called with the
		-- result of obj:renderTitle, plus any other optional arguments.
		-- Returns string
		function obj:renderDisplayTitle(...)
			checkSelf(self, 'renderDisplayTitle')
			return mw.getCurrentFrame():callParserFunction(
				'DISPLAYTITLE',
				self:renderTitle(),
				...
			)
		end

		-- Returns an expanded DISPLAYTITLE parser function called with the
		-- result of obj:renderTitle, plus any other optional arguments, plus
		-- any tracking categories.
		-- Returns string
		function obj:render(...)
			checkSelf(self, 'render')
			local ret = self:renderDisplayTitle(...)
			for cat in pairs(categories) do
				ret = ret .. string.format(
					'[[Category:%s]]',
					cat
				)
			end
			return ret
		end

		return obj
	end
end

--------------------------------------------------------------------------------
-- Exports
--------------------------------------------------------------------------------

local p = {}

local function getArgs(frame, wrapper)
	assert(type(wrapper) == 'string', 'wrapper was not a string')
	return require('Module:Arguments').getArgs(frame, {
		wrappers = wrapper
	})
end

-- Main function for {{italic title}}
function p._main(args)
	checkType('_main', 1, args, 'table')
	local italicTitle = ItalicTitle.new()
	italicTitle:parseTitle{
		title = mw.title.getCurrentTitle(),
		ignoreDab = yesno(args.all, false)
	}
	if args.string then
		italicTitle:italicizeSubstring(args.string)
	else
		italicTitle:italicize('title')
	end
	return italicTitle:render(args[1])
end

function p.main(frame)
	return p._main(getArgs(frame, 'Template:Italic title'))
end

function p._dabonly(args)
	return ItalicTitle.new()
		:italicize('dab')
		:render(args[1])
end

function p.dabonly(frame)
	return p._dabonly(getArgs(frame, 'Template:Italic dab'))
end


return p