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This module provides many useful utility functions for creating and processing wikilinks within Wiktionary. It is used by the linking templates {{m}} and {{l}} through the functions in Module:links/templates.

full_link

full_link(data, face, allowSelfLink, dontLinkRecons)

Creates a full link, with annotations (see format_link_annotations), in the style of {{l}} or {{m}}.

The first argument, data, must be a table. It contains the various elements that can be supplied as parameters to {{l}} or {{m}}:

{
	term = entry_to_link_to,
	alt = link_text_or_displayed_text,
	lang = language_object,
	sc = script_object,
	id = sense_id,
	genders = { "gender1", "gender2", ... },
	tr = transliteration,
	gloss = gloss,
	pos = part_of_speech_tag,
	lit = literal_translation,
	accel = accelerated_creation_tags,
	interwiki = interwiki,
}

Any one of the items in the data table may be nil, but an error will be shown if neither term nor alt nor tr is present.

Thus, calling full_link{ term = term, lang = lang, sc = sc }, where term is an entry name, lang is a language object from Module:languages, and sc is a script object from Module:scripts, will give a plain link similar to the one produced by the template {{l}}, and calling full_link( { term = term, lang = lang, sc = sc }, "term" ) will give a link similar to the one produced by the template {{m}}.

The function will:

  • Try to determine the script, based on the characters found in the term or alt argument, if the script was not given.
  • Call language_link on the term or alt forms, to remove diacritics in the page name, process any embedded wikilinks and create links to Reconstruction or Appendix pages when necessary.
  • Call Module:script utilities#tag_text to add the appropriate language and script tags to the term, and to italicize terms written in the Latin script if necessary. Accelerated creation tags, as used by WT:ACCEL, are included.
  • Generate a transliteration, based on the alt or term arguments, if the script is not Latin and no transliteration was provided.
  • Add the annotations (transliteration, gender, gloss etc.) after the link.

format_link_annotations

format_link_annotations(lang, info)

Formats the annotations that are displayed with a link created by full_link. Annotations are the extra bits of information that are displayed following the linked term, and include things such as gender, transliteration, gloss and so on. The first argument is the language object, the second is a table possessing some or all of the following keys:

genders
Table containing a list of gender specifications in the style of Module:gender and number.
tr
Transliteration.
gloss
Gloss that translates the term in the link, or gives some other descriptive information.
pos
Part of speech of the linked term. If the given argument matches one of the templates in Category:Part of speech tags, then call that to show a part-of-speech tag. Otherwise, just show the given text as it is.
lit
Literal meaning of the term, if the usual meaning is figurative or idiomatic.

Any of the above values can be omitted from the info argument. If a completely empty table is given (with no annotations at all), then an empty string is returned.

language_link

language_link(data, allowSelfLink, dontLinkRecons)

Creates a basic link to the given term. It links to the language section (such as ==English==), but it does not add language and script wrappers, so any code that uses this function should call the tag_text from Module:script utilities to add such wrappers itself at some point.

The first argument, data, may contain the following items, a subset of the items used in the data argument of full_link. If any other items are included, they are ignored.

{
	term = entry_to_link_to,
	alt = link_text_or_displayed_text,
	lang = language_object,
	id = sense_id,
}
term
Text to turn into a link. This is generally the name of a page. The text can contain wikilinks already embedded in it. These are processed individually just like a single link would be. The alt argument is ignored in this case.
alt (optional)
The alternative display for the link, if different from the linked page. If this is nil, the text argument is used instead (much like regular wikilinks). If text contains wikilinks in it, this argument is ignored and has no effect. (Links in which the alt is ignored are tracked with the tracking template links/alt-ignored.)
lang
The language object for the term being linked. If this argument is defined, the function will determine the language's canonical name (see Template:language data documentation), and point the link or links in the term to the language's section of an entry, or to a language-specific senseid if the id argument is defined.
id (optional)
Sense id string. If this argument is defined, the link will point to a language-specific sense id (identifier) created by the template {{senseid}}. A sense id consists of the language's canonical name, a hyphen (-), and the string that was supplied as the id argument. This is useful when a term has more than one sense in a language. If the term argument contains wikilinks, this argument is ignored. (Links in which the sense id is ignored are tracked with the tracking template links/id-ignored.)

The second argument is as follows:

allowSelfLink
If true, the function will also generate links to the current page. The default (false) will not generate a link but generate a bolded "self link" instead.

The following special options are processed for each link (both simple text and with embedded wikilinks):

  • The target page name will be processed to generate the correct entry name. This is done by the makeEntryName function in Module:languages, using the entry_name replacements in the language's data file (see Template:language data documentation for more information). This function is generally used to automatically strip dictionary-only diacritics that are not part of the normal written form of a language.
  • If the text starts with *, then the term is considered a reconstructed term, and a link to the Reconstruction: namespace will be created. If the text contains embedded wikilinks, then * is automatically applied to each one individually, while preserving the displayed form of each link as it was given. This allows linking to phrases containing multiple reconstructed terms, while only showing the * once at the beginning.
  • If the text starts with :, then the link is treated as "raw" and the above steps are skipped. This can be used in rare cases where the page name begins with * or if diacritics should not be stripped. For example:
    • {{l|en|*nix}} links to the nonexistent page Reconstruction:English/nix (* is interpreted as a reconstruction), but {{l|en|:*nix}} links to *nix.
    • {{l|sl|Franche-Comté}} links to the nonexistent page Franche-Comte (é is converted to e by makeEntryName), but {{l|sl|:Franche-Comté}} links to Franche-Comté.

remove_links

remove_links(text)

Replaces all wikilinks with their displayed text, and removes any categories. This function can be invoked either from a template or from another module.

  • [[page|displayed text]]displayed text
  • [[page and displayed text]]page and displayed text
  • [[Category:English lemmas|WORD]](nothing)

Contents of data module

Unsupported titles
High-memory entries

local export = {}

--[=[
	[[Unsupported titles]] and pages with high
	memory usage are listed at [[Module:links/data]].
	
	Other modules used:
		[[Module:script utilities]]
		[[Module:scripts]]
		[[Module:languages]] and its submodules
		[[Module:gender and number]]
		[[Module:utilities]]
		[[Module:string]]
		[[Module:debug]]
]=]

-- These are prefixed with u to avoid confusion with the default string methods
-- of the same name.
local usub = mw.ustring.sub

local table_insert = table.insert
local table_concat = table.concat

local ignore_cap = {
	["ko"] = true,
}

local phonetic_extraction = {
	["th"] = "Module:th",
	["km"] = "Module:km",
}

local pos_tags = {
	["a"] = "adjective",
	["adv"] = "adverb",
	["int"] = "interjection",
	["n"] = "noun",
	["pron"] = "pronoun",
	["v"] = "verb",
	["vi"] = "intransitive verb",
	["vt"] = "transitive verb",
	["vti"] = "transitive and intransitive verb",
}

function export.getLinkPage(target, lang)
	if mw.loadData("Module:links/data").unsupported_titles[target] then
		return "Unsupported titles/" .. mw.loadData("Module:links/data").unsupported_titles[target]
	end
	
	-- If the link contains unexpanded template parameters, then don't create a link.
	if target:find("{{{", nil, true) then
		return nil
	end
	
	if target:sub(1, 1) == ":" or target:sub(1, 2) == "w:" or target:sub(1, 10) == "wikipedia:" then
		return target
	end
	
	-- Remove diacritics from the page name
	target = lang:makeEntryName(target)
	
	-- Link to appendix for reconstructed terms and terms in appendix-only languages
	if target:find("^*.") then
		if lang:getCode() == "und" then
			return nil
		end
		
		target = "Reconstruction:" .. lang:getCanonicalName() .. "/" .. usub(target, 2)
	elseif lang:getType() == "reconstructed" then
		error("The specified language " .. lang:getCanonicalName() .. " is unattested, while the given word is not marked with '*' to indicate that it is reconstructed")
	elseif lang:getType() == "appendix-constructed" then
		target = "Appendix:" .. lang:getCanonicalName() .. "/" .. target
	end
	
	return target
end

-- Make a language-specific link from given link's parts
local function makeLangLink(link, lang, id, allowSelfLink)
	-- Temporary tracking code
	if (lang:getCode() == "sma" or lang:getCode() == "sju" or lang:getCode() == "sje" or lang:getCode() == "smj" or lang:getCode() == "se" or lang:getCode() == "smn" or lang:getCode() == "sia" or lang:getCode() == "sjk" or lang:getCode() == "sms" or lang:getCode() == "sjd" or lang:getCode() == "sjt") then
		if link.display and string.find(link.display, "'") then
			require("Module:debug").track("links/Sami apostrophe display")
		elseif link.target and string.find(link.target, "'") then
			require("Module:debug").track("links/Sami apostrophe target")
		end
	end
	
	-- Find fragments (when link didn't come from parseLink).
	-- Prevents {{l|en|word#Etymology 2|word}} from linking to [[word#Etymology 2#English]].
	if link.fragment == nil then
		-- Replace numeric character references with the corresponding character ( → '),
		-- as they contain #, which would be misinterpreted (wa'a → waa → pagename wa&, fragment 29;a).
		link.target = link.target:gsub("&#(%d+);",
			function(number) return mw.ustring.char(tonumber(number)) end)
		local first, second = link.target:match("^([^#]+)#(.+)$")
		if first then
			link.target, link.fragment = first, second
		end
	end
	
	-- If there is no display form, then create a default one
	if not link.display then
		link.display = link.target
		
		-- Strip the prefix from the displayed form
		-- TODO: other interwiki links?
		if link.display:sub(1, 1) == ":" and not mw.loadData("Module:links/data").unsupported_titles[link.display] then
			link.display = link.display:sub(2) -- remove colon from beginning
		else
			local prefix = link.display:match("^([^:]+):")
			local prefixes = {
				w = true,
				wikipedia = true,
			}
			
			if prefixes[prefix] then
				link.display = link.display:sub(#prefix + 2) -- remove prefix plus colon
			end
		end
	end
	
	-- Process the target
	link.target = export.getLinkPage(link.target, lang)
	
	if not link.target then
		return link.display
	end
	
	-- If the target is the same as the current page, then return a "self-link" like the software does
	if not allowSelfLink and not id and (link.target == mw.title.getCurrentTitle().prefixedText or link.target == ":" .. mw.title.getCurrentTitle().prefixedText) then
		return "<strong class=\"selflink\">" .. link.display .. "</strong>"
	end
	
	--[[
		Add fragment
		Do not add a section link to "Undetermined", as such sections do not exist and are invalid.
		TabbedLanguages handles links without a section by linking to the "last visited" section,
		but adding "Undetermined" would break that feature.
		For localized prefixes that make syntax error, please use the format: ["xyz"] = true,
	]]
	local prefix = link.target:match("^:?([^:]+):")
	local prefixes = {
		w = true,
		wikipedia = true,
		Category = true,
	}
	
	if not (prefix and prefixes[prefix]) then
		if link.fragment or link.target:find("#$") then
			require("Module:debug").track {
				"links/fragment",
				"links/fragment/" .. lang:getCode()
			}
		end
		
		if not link.fragment and lang:getCode() ~= "und" then
			if id then
				link.fragment = require("Module:utilities").make_id(lang, id)
			elseif not mw.ustring.find(link.target, "^Appendix:") and not mw.ustring.find(link.target, "^Reconstruction:") then
				link.fragment = lang:getCanonicalName()
			end
		end
		
		-- This allows linking to pages like [[sms:a]] without it being treated weirdly.
		link.target = link.target:gsub(":", "&#x3a;")
	end
	
	return "[[" .. link.target .. (link.fragment and "#" .. link.fragment or "") .. "|" .. link.display .. "]]"
end


-- Split a link into its parts
local function parseLink(linktext)
	local link = { target = linktext }
	local first, second = link.target:match("^([^|]+)|(.+)$")
	
	if first then
		link.target = first
		link.display = second
	else
		link.display = link.target
	end
	
	first, second = link.target:match("^(.+)#(.+)$")
	
	if first then
		link.target = first
		link.fragment = second
	else
		-- So that makeLangLink does not look for a fragment again
		link.fragment = false
	end
	
	return link
end


-- Creates a basic wikilink to the given term. If the text already contains
-- links, these are replaced with links to the correct section.
function export.language_link(data, allowSelfLink, dontLinkRecons)
	if type(data) ~= "table" then
		error("The first argument to the function language_link must be a table. See Module:links/documentation for more information.")
	end
	
	local text = data.term
	
	if ignore_cap[data.lang:getCode()] and text then
		text = text:gsub("%^", "")
	end
	
	-- If the text begins with * and another character,
	-- then act as if each link begins with *
	local allReconstructed = false
	
	if text:find("^*.") then
		allReconstructed = true
	end
	
	-- Do we have embedded wikilinks?
	if text:find("[[", nil, true) then
		--[=[
		[[Special:WhatLinksHere/Template:tracking/links/alt-ignored]]
		[[Special:WhatLinksHere/Template:tracking/links/id-ignored]]
		]=]
		
		if data.alt then
			require("Module:debug").track("links/alt-ignored")
			mw.log("(from Module:links)", "text with embedded wikilinks:", text, "ignored alt:", data.alt, "lang:", data.lang:getCode())
		end
		
		if data.id then
			require("Module:debug").track("links/id-ignored")
			mw.log("(from Module:links)", "text with embedded wikilinks:", text, "ignored id:", data.id, "lang:", data.lang:getCode())
		end
		
		-- Begins and ends with a wikilink tag
		if text:find("^%[%[(.+)%]%]$") then
			-- There are no [ ] in between.
			-- This makes the wikilink tag redundant.
			if text:find("^%[%[[^%[%]]+%]%]$") then
				require("Module:debug").track("links/redundant wikilink")
			else
				local temp = text:gsub("^%[%[(.+)%]%]$", "%1")
				temp = temp:gsub("%]%], %[%[", "|")
				
				if not temp:find("[%[%]]") then
					require("Module:debug").track("links/list")
				end
			end
		end
		
		text = text:gsub("%[%[([^%]]+)%]%]",
			function(linktext)
				local link = parseLink(linktext)
				
				if allReconstructed then
					link.target = "*" .. link.target
				end
				
				return makeLangLink(link, data.lang, data.id, allowSelfLink, dontLinkRecons)
			end)
		
		-- Remove the extra * at the beginning if it's immediately followed
		-- by a link whose display begins with * too
		if allReconstructed then
			text = text:gsub("^%*%[%[([^|%]]+)|%*", "[[%1|*")
		end
	else
		-- There is no embedded wikilink, make a link using the parameters.
		text = makeLangLink({ target = text, display = data.alt }, data.lang, data.id, allowSelfLink, dontLinkRecons)
	end
	
	return text
end

function export.mark(text, itemType, face, lang)
	local tag = { "", "" }
	
	if itemType == "gloss" then
		tag = { '<span class="mention-gloss-double-quote">“</span><span class="mention-gloss">', '</span><span class="mention-gloss-double-quote">”</span>' }
	elseif itemType == "tr" then
		if face == "term" then
			tag = { '<span lang="' .. lang:getCode() .. '" class="tr mention-tr Latn">', '</span>' }
		else
			tag = { '<span lang="' .. lang:getCode() .. '" class="tr Latn">', '</span>' }
		end
	elseif itemType == "ts" then
		tag = { '<span class="ts mention-ts Latn">/', '/</span>' }
	elseif itemType == "annotations" then
		tag = { '<span class="mention-gloss-paren annotation-paren">(</span>', '<span class="mention-gloss-paren annotation-paren">)</span>' }
	end
	
	if type(text) == "string" then
		return tag[1] .. text .. tag[2]
	else
		return ""
	end
end

-- Format the annotations (things following the linked term)
function export.format_link_annotations(data, face)
	local output = {}
	
	-- Interwiki link
	if data.interwiki then
		table_insert(output, data.interwiki)
	end
	
	-- Genders
	if type(data.genders) ~= "table" then
		data.genders = { data.genders }
	end
	
	if data.genders and #data.genders > 0 then
		local m_gen = require("Module:gender and number")
		table_insert(output, "&nbsp;" .. m_gen.format_list(data.genders, data.lang))
	end
	
	local annotations = {}
	
	-- Transliteration and transcription
	if data.tr or data.ts then
		local kind
		if face == "term" then
			kind = face
		else
			kind = "default"
		end
		
		if data.tr and data.ts then
			table_insert(annotations, require("Module:script utilities").tag_translit(data.tr, data.lang, kind) .. " " .. export.mark(data.ts, "ts"))
		elseif data.ts then
			table_insert(annotations, export.mark(data.ts, "ts"))
		else
			table_insert(annotations, require("Module:script utilities").tag_translit(data.tr, data.lang, kind))
		end
	end
	
	-- Gloss/translation
	if data.gloss then
		table_insert(annotations, export.mark(data.gloss, "gloss"))
	end
	
	-- Part of speech
	if data.pos then
		-- debug category for pos= containing transcriptions
		if mw.ustring.match(data.pos, "/[^><]*/") ~= nil then
			data.pos = data.pos .. "[[Category:links likely containing transcriptions in pos]]"
		end

		table_insert(annotations, pos_tags[data.pos] or data.pos)
	end
	
	-- Literal/sum-of-parts meaning
	if data.lit then
		table_insert(annotations, "literally " .. export.mark(data.lit, "gloss"))
	end
	
	if #annotations > 0 then
		table_insert(output, " " .. export.mark(table_concat(annotations, ", "), "annotations"))
	end
	
	return table_concat(output)
end

-- A version of {{l}} or {{m}} that can be called from other modules too
function export.full_link(data, face, allowSelfLink, dontLinkRecons)
	if type(data) ~= "table" then
		error("The first argument to the function full_link must be a table. See Module:links/documentation for more information.")
	end
	
	-- Create the link
	local output = {}
	local categories = {}
	local link = ""
	local annotations
	
	--local m_utilities = require("Module:utilities")
	
	-- Is there any text to show?
	if (data.term or data.alt) then
		-- Try to detect the script if it was not provided
		if not data.sc then
			data.sc = require("Module:scripts").findBestScript(data.alt or data.term, data.lang)
		else
			-- Track uses of sc parameter
			local best = require("Module:scripts").findBestScript(data.alt or data.term, data.lang)
			require("Module:debug").track("links/sc")
			
			if data.sc:getCode() == best:getCode() then
				require("Module:debug").track("links/sc/redundant")
				require("Module:debug").track("links/sc/redundant/" .. data.sc:getCode())
			else
				require("Module:debug").track("links/sc/needed")
				require("Module:debug").track("links/sc/needed/" .. data.sc:getCode())
			end
		end
		
		local class = ""
		
		if data.accel then
			if type(data.accel) == "table" then
				data.accel.form = data.accel.form and data.accel.form .. "-form-of" or ""
				data.accel.gender = data.accel.gender and "gender-" .. data.accel.gender or ""
				data.accel.translit = data.accel.translit and "transliteration-" .. data.accel.translit or ""
				data.accel.lemma = data.accel.lemma and "origin-" .. data.accel.lemma:gsub("%%", "."):gsub(" ", "_") or ""  -- This is decoded again by [[WT:ACCEL]].
				data.accel.lemma_translit = data.accel.lemma_translit and "origin-transliteration-" .. data.accel.lemma_translit or ""
				data.accel.no_store = data.accel.no_store and "form-of-nostore" or ""
				
				data.accel =
					data.accel.form .. " " ..
					data.accel.gender .. " " ..
					data.accel.translit .. " " ..
					data.accel.lemma .. " " ..
					data.accel.lemma_translit .. " " ..
					data.accel.no_store .. " "
			else
				require("Module:debug").track("links/accel not table")
				require("Module:debug").track("links/accel not table/" .. data.lang:getCode())
			end
			
			class = "form-of lang-" .. data.lang:getCode() .. " " .. data.accel
			
			-- Tracking to find out which languages currently use acceleration but have no [[Module:accel]] submodule
			local success, lang_module = pcall(require, "Module:accel/" .. data.lang:getCode())
			
			if not success then
				require("Module:debug").track("links/no accel")
				require("Module:debug").track("links/no accel/" .. data.lang:getCode())
			end
		end
		
		-- Only make a link if the term has been given, otherwise just show the alt text without a link
		link = require("Module:script utilities").tag_text(data.term and export.language_link(data, allowSelfLink, dontLinkRecons) or data.alt, data.lang, data.sc, face, class)
	else
		--[[	No term to show.
				Is there at least a transliteration we can work from?	]]
		link = require("Module:script utilities").request_script(data.lang, data.sc)
		
		if link == "" or not data.tr or data.tr == "-" then
			-- No link to show, and no transliteration either. Show a term request.
			local category = ""
			
			if mw.title.getCurrentTitle().nsText ~= "Template" then
				table_insert(categories, "[[Category:" .. data.lang:getCanonicalName() .. " term requests]]")
			end
			
			link = "<small>[Term?]</small>"
		end
	end
	
	table_insert(output, link)
	
	if data.tr == "" or data.tr == "-" then
		data.tr = nil
	
	elseif phonetic_extraction[data.lang:getCode()] then
		local m_phonetic = require(phonetic_extraction[data.lang:getCode()])
		data.tr = data.tr or m_phonetic.getTranslit(export.remove_links(data.term))
	
	elseif (data.term or data.alt)
			and not ((data.sc:getCode():find("Latn", nil, true)) or data.sc:getCode() == "Latinx") then
		
		if not mw.loadData("Module:links/data").high_memory_entries[mw.title.getCurrentTitle().text] or not data.tr then
			-- Try to generate a transliteration if necessary
			local automated_tr = data.lang:transliterate(export.remove_links(data.alt or data.term), data.sc)
			
			if automated_tr then
				local manual_tr = data.tr
				
				if manual_tr then
					if manual_tr == automated_tr then
						table_insert(categories,
							"[[Category:Terms with redundant transliterations]]"
									.. "[[Category:Terms with redundant transliterations/" .. data.lang:getCode() .. "]]")
					else
						-- Prevents Arabic root categories from flooding the tracking categories.
						if mw.title.getCurrentTitle().nsText ~= "Category" then
							table_insert(categories,
								"[[Category:Terms with manual transliterations different from the automated ones]]"
										.. "[[Category:Terms with manual transliterations different from the automated ones/" .. data.lang:getCode() .. "]]")
						end
					end
				end
				
				if (not manual_tr) or data.lang:overrideManualTranslit() then
					data.tr = automated_tr
				end
			end
		end
	end
	
	-- Link to the transliteration entry for languages that require this
	if data.tr and data.lang:link_tr() then
		data.tr = export.language_link { lang = data.lang, term = data.tr }
	end
	
	table_insert(output, export.format_link_annotations(data, face))
	
	return table_concat(output) .. table_concat(categories)
end


--[[	Strips links: deletes category links,
		the targets of piped links,
		and all double square brackets.			]]
function export.remove_links(text)
	if type(text) == "table" then
		text = text.args[1]
	end
	
	if not text or text == "" then
		return ""
	end
	
	text = mw.ustring.gsub(text, "%[%[Category:[^|%]]-|?[^|%]]-%]%]", "")
	text = text:gsub("%[%[[^|%]]-|", "")
	text = text:gsub("%[%[", "")
	text = text:gsub("%]%]", "")
	
	return text
end

function export.english_links(text)
	local lang = require("Module:languages").getByCode("en")
	
	-- Parentheses around function call to remove second return value, the
	-- number of replacements.
	return (text:gsub("%[%[([^%]]+)%]%]",
		function(linktext)
			local link = parseLink(linktext)
			return makeLangLink(link, lang, nil, true, false)
		end))
end

function export.light_link(data)
	local language_names = mw.loadData("Module:languages/code to canonical name")
	local script_codes = mw.loadData("Module:scripts/codes")
	
	if data.langCode then
		data.langName = language_names[data.langCode] or error('The language code "' .. data.langCode .. '" is not recognized.')
	else
		error('Language code is required.')
	end
	
	if not data.term then
		error('Term to link to is required.')
	end
	
	if data.scCode then
		if not script_codes[data.scCode] then
			error('The script code "' .. data.sc .. '" is not recognized.')
		end
	else
		error("The function light_link requires a script code.")
	end
	
	local fragment
	if data.id then
		fragment = data.langName .. "-" .. mw.uri.encode(data.id, "WIKI")
	else
		fragment = data.langName
	end
	
	return table_concat {
		'<span class="', data.scCode, '" lang="', data.langCode,
		'">[[', data.term, "#", fragment, "|", (data.alt or data.term), "]]</span>"
	}
end

--[=[
	For example, Norwegian_Bokm.C3.A5l → Norwegian_Bokmål. 0xC3 and 0xA5 are the
	hexadecimal-base representation of the two bytes used to encode the character
	å in the UTF-8 encoding:
		11000011 10100101
	
	Note that the bytes used to represent a character are actually different from
	the Unicode codepoint. For å, the codepoint is 0xE5. The bits (digits) that
	actually spell the codepoint are found in the brackets: 110[00011] 10[100101].
	For further explanation, see [[w:UTF-8#Description]].
]=]

-- The character class %x should not be used, as it includes the characters a-f,
-- which do not occur in these anchor encodings.
local capitalHex = "[0-9A-F]"

local function decodeAnchor(anchor)
	return (anchor:gsub("%.(" .. capitalHex .. capitalHex .. ")",
		function(hexByte)
			return string.char(tonumber(hexByte, 16))
		end))
end

function export.section_link(link)
	if type(link) ~= "string" then
		error("The first argument to section_link was a " .. type(link) .. ", but it should be a string.")
	end
	
	link = link:gsub("_", " ")
	
	local numberSigns = require("Module:string").count(link, "#")
	
	if numberSigns > 1 then
		error("The section link should only contain one number sign (#).")
	end
	
	local page, section = link:match("^([^#]+)#(.+)$")
	
	if page and section then
		section = decodeAnchor(section)
		
		-- URI-encode (percent-encode) section to allow square brackets, [],
		-- in section name. If not percent-encoded, they prevent the parser from
		-- recognizing the link.
		return table_concat { "[[", page, "#", mw.uri.encode(section, "WIKI"), "|", page, " § ", section, "]]" }
	else
		error('The function "' .. section_link .. '" could not find a number sign marking a section name.')
	end
end

return export