Editing Module:Hatnote

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--                              Module:Hatnote                                --
--                                                                            --
-- This module produces hatnote links and links to related articles. It       --
-- implements the {{rellink}} and {{hatnote}} meta-templates, and includes    --
-- helper functions for other Lua modules to format hatnote links.            --
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local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local mArguments -- lazily initialise [[Module:Arguments]]

local p = {}

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-- Helper functions
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local function getArgs(frame)
	-- Fetches the arguments from the parent frame. Whitespace is trimmed and
	-- blanks are removed.
	mArguments = require('Module:Arguments')
	return mArguments.getArgs(frame, {parentOnly = true})
end

local function removeInitialColon(s)
	-- Removes the initial colon from a string, if present.
	return s:match('^:?(.*)')
end

function p._findNamespaceId(link, removeColon)
	-- Finds the namespace id (namespace number) of a link or a pagename. This
	-- function will not work if the link is enclosed in double brackets. Colons
	-- are trimmed from the start of the link by default. To skip colon
	-- trimming, set the removeColon parameter to true.
	checkType('_findNamespaceId', 1, link, 'string')
	checkType('_findNamespaceId', 2, removeColon, 'boolean', true)
	if removeColon ~= false then
		link = removeInitialColon(link)
	end
	local namespace = link:match('^(.-):')
	if namespace then
		local nsTable = mw.site.namespaces[namespace]
		if nsTable then
			return nsTable.id
		end
	end
	return 0
end

function p._formatPages(...)
	-- Formats a list of pages using formatLink and returns it as an array. Nil
	-- values are not allowed.
	local pages = {...}
	local ret = {}
	for i, page in ipairs(pages) do
		ret[i] = p._formatLink(page)
	end
	return ret
end

function p._formatPageTables(...)
	-- Takes a list of page/display tables and returns it as a list of
	-- formatted links. Nil values are not allowed.
	local pages = {...}
	local links = {}
	for i, t in ipairs(pages) do
		checkType('_formatPageTables', i, t, 'table')
		local link = t[1]
		local display = t[2]
		links[i] = p._formatLink(link, display)
	end
	return links
end

function p._makeWikitextError(msg)
	-- Formats an error message to be returned to wikitext.
	checkType('_makeWikitextError', 1, msg, 'string')
	local errorCategory = 'Hatnote templates with errors'
	local errorCategoryLink = errorCategory
		and string.format(
			'[[%s:%s]]',
			mw.site.namespaces[14].name,
			errorCategory
		)
		or ''
	return string.format(
		'<strong class="error">Error: %s.</strong>%s',
		msg,
		errorCategoryLink
	)
end

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-- Format link
--
-- Makes a wikilink from the given link and display values. Links are escaped
-- with colons if necessary, and links to sections are detected and displayed
-- with " § " as a separator rather than the standard MediaWiki "#".
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function p.formatLink(frame)
	local args = getArgs(frame)
	local link = args[1]
	local display = args[2]
	if not link then
		return p._makeWikitextError('no link specified')
	end
	return p._formatLink(link, display)
end

function p._formatLink(link, display)
	-- Find whether we need to use the colon trick or not. We need to use the
	-- colon trick for categories and files, as otherwise category links
	-- categorise the page and file links display the file.
	checkType('_formatLink', 1, link, 'string')
	checkType('_formatLink', 2, display, 'string', true)
	link = removeInitialColon(link)
	local namespace = p._findNamespaceId(link, false)
	local colon
	if namespace == 6 or namespace == 14 then
		colon = ':'
	else
		colon = ''
	end

	-- Find the display value.
	if not display then
		local page, section = link:match('^(.-)#(.*)$')
		if page then
			display = page .. ' § ' .. section
		end
	end

	-- Assemble the link.
	if display then
		return string.format('[[%s%s|%s]]', colon, link, display)
	else
		return string.format('[[%s%s]]', colon, link)
	end
end

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-- Hatnote
--
-- Produces standard hatnote text. Implements the {{hatnote}} template.
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function p.hatnote(frame)
	local args = getArgs(frame)
	local s = args[1]
	local options = {}
	if not s then
		return p._makeWikitextError('no text specified')
	end
	options.extraclasses = args.extraclasses
	options.selfref = args.selfref
	return p._hatnote(s, options)
end

function p._hatnote(s, options)
	checkType('_hatnote', 1, s, 'string')
	checkType('_hatnote', 2, options, 'table', true)
	local classes = {'rellink'}
	local extraclasses = options.extraclasses
	local selfref = options.selfref
	if type(extraclasses) == 'string' then
		classes[#classes + 1] = extraclasses
	end
	if selfref then
		classes[#classes + 1] = 'selfref'
	end
	return string.format(
		'<div class="%s">%s</div>',
		table.concat(classes, ' '),
		s
	)
end

return p