Module:Unicode data

Usage

This module provides functions that access information on Unicode code points. The information is retrieved from data modules generated from the Unicode Character Database, or derived by rules given in the Unicode Specification. It and its submodules were copied from English Wiktionary and then modified; see there for more information.

Parameters and functions

code point

The code point is to be entered as hexadecimal value. For example, U+00A9 © COPYRIGHT SIGN:

|A9_hex

|0xA9_hex

|0x00A9_hex

|0x00a9_hex

{{#invoke:Unicode data|lookup|name|0x00A9}} → COPYRIGHT SIGN

Incorrect or unintended results:

169_dec: {{#invoke:Unicode data|lookup|name|169}} → LATIN SMALL LETTER U WITH TILDE File:Red x.svgN —"U+00A9" © expected; but is read as 00A9_hex (that is, 361_dec

U+00A9 {{#invoke:Unicode data|lookup|name|U+00A9}} File:Red x.svgN —do not use "U+" prefix

غ {{#invoke:Unicode data|lookup|name|غ}} File:Red x.svgN —cannot enter a character as codepoint

"lookup" and "is" functions

lookup, is

Template-invokable functions that allow access to the functions starting with lookup and is.For most of the functions, add the code point in hexadecimal base as the next parameter. For is"|Latin, is|rtl, and is|valid_pagename, add character string. HTML character references in the text are decoded by the module into code points.

For example, {{#invoke:Unicode data|is|Latin|àzàhàr̃iyyā̀}} → .

Internally, in modules, these functions are named using underscore: lookup_name|code point ← lookup_name

For &A9; ©: {{#invoke:Unicode data|lookup|name|A9}} → COPYRIGHT SIGN

Functions overview

This table:

• Code points: enter hexadecimal value, for example |0x0061 or |61; not |U+0061.

Topic	Function	Parameter type (string=by character(s); c.p. by 0xHex value)	Example	Returns	Character
Unicode character name	|lookup|name	code point	{{#invoke:Unicode data|lookup|name|0xA9}} {{#invoke:Unicode data|lookup|name|0x0007}}	COPYRIGHT SIGN <control-0007>	© &#x0007;
Scripts	|lookup|script	code point	{{#invoke:Unicode data|lookup|script|A061}}		ꁡ
Blocks	|lookup|block	code point	{{#invoke:Unicode data|lookup|block|A061}}	Yi Syllables	ꁡ
Planes	|lookup|plane	code point	{{#invoke:Unicode data|lookup|plane|0xA9}} {{#invoke:Unicode data|lookup|plane|0x1F608}}	Basic Multilingual Plane Supplementary Multilingual Plane	© 😈
General Category	|lookup|category	code point	{{#invoke:Unicode data|lookup|category|0xA9}} {{#invoke:Unicode data|lookup|category|0x002B}}	So Sm	© +
Controls	|is|control	code point	{{#invoke:Unicode data|lookup|control|A9}} {{#invoke:Unicode data|lookup|control|FFFF}}		© &#xFFFF;
Latin script	|is|Latin	string	{{#invoke:Unicode data|is|Latin|abcŁíā̀}} {{#invoke:Unicode data|is|Latin|abc文xyz}}
WP:Article title (WP:NCTR)	|is|valid_pagename	string	{{#invoke:Unicode data|is|valid_pagename|Main_page}} {{#invoke:Unicode data|is|valid_pagename|# (disambiguation)}}	false
Bidirectionality, right-to-left scripts	|is|rtl	string	{{#invoke:Unicode data|is|rtl|ش}} {{#invoke:Unicode data|is|rtl|34}}	false	ش 4
Combining character	|is|combining	code point	{{#invoke:Unicode data|is|combining|0300}} {{#invoke:Unicode data|is|combining|64}}		̀ d
Character assignation	|is|assigned	code point	{{#invoke:Unicode data|is|assigned|A061}} {{#invoke:Unicode data|is|assigned|FFEF}}		ꁡ ;
Printable	|is|printable	code point	{{#invoke:Unicode data|is|printable|0061}} {{#invoke:Unicode data|is|printable|0007}} {{#invoke:Unicode data|is|printable|FFFF}}	>< >< ><	>a< >&#x0007;< >&#xFFFF;<
Whitespace character § Unicode	|is|whitespace	code point	{{#invoke:Unicode data|is|whitespace|0x20}} {{#invoke:Unicode data|is|whitespace|0xA0}} {{#invoke:Unicode data|is|whitespace|0x64}}	>true< >true< NBSP ><	> < > < >d<
Hangul	|Hangul		[application unknown]		&#x; &#x;
Alias names	|aliases		[application unknown]		&#x; &#x;
Combining class	|		[application unknown]		&#x; &#x;
Age	|		[application unknown]
get_best_script	|get_best_script		[application unknown]

Data modules

The data used by functions in this module is found in submodules. Some are generated by AWK scripts shown at User:Kephir/Unicode on English Wiktionary, others by Lua scripts on the /make subpages of the submodules.

• Module:Unicode data/age: 'Age' of a character, that is: version introduction number.
• Module:Unicode data/aliases: the formal name aliases for characters (from NameAliases.txt)
• Module:Unicode data/blocks: the list of Unicode blocks (from Blocks.txt)
• Module:Unicode data/category: data mapping characters to their General Category (from DerivedGeneralCategory.txt)
• Module:Unicode data/combining: data mapping characters to their Combining Classes (from DerivedCombiningClass.txt)
• Module:Unicode data/control: data for identifying characters that belong to the General Categories of Separator and Other (from DerivedGeneralCategory.txt)
• Module:Unicode data/derived core properties:
• Module:Unicode data/Hangul: data used to generate the names of Hangul syllables (from Jamo.txt)
• Module:Unicode data/names/* (000hh, .., 0E0hh; eg ../names/000): names
• Module:Unicode data/scripts: data mapping characters to their Unicode script properties (from Scripts.txt).

The name data modules (Module:Unicode data/names/xxx) were compiled from UnicodeData.txt. Each one contains, at maximum, code points U+xxx000 to U+xxxFFF.

Copyright

The Unicode database is released by Unicode Inc. under the following terms:

Copyright © 1991-2018 Unicode, Inc. All rights reserved. Distributed under the Terms of Use in https://www.unicode.org/copyright.html.

Permission is hereby granted, free of charge, to any person obtaining a copy of the Unicode data files and any associated documentation (the "Data Files") or Unicode software and any associated documentation (the "Software") to deal in the Data Files or Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Data Files or Software, and to permit persons to whom the Data Files or Software are furnished to do so, provided that either (a) this copyright and permission notice appear with all copies of the Data Files or Software, or (b) this copyright and permission notice appear in associated Documentation.

THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THE DATA FILES OR SOFTWARE.

Except as contained in this notice, the name of a copyright holder shall not be used in advertising or otherwise to promote the sale, use or other dealings in these Data Files or Software without prior written authorization of the copyright holder.

Known issues

• Reading data like Module:Unicode data/aliases not provided nor documented
• Test fail: lookup_category U+FFFF (<noncharacter-FFFF>) expected: Cn.

{{#invoke:Unicode data|lookup|category|0xFFFF}} → [Nil]

See also

• Named entities: for example, U+22C1 ⋁ N-ARY LOGICAL OR: {{#invoke:LoadData|Numcr2namecr|0x22C1}} → &bigvee;, &Vee;, &xvee;

---

local p = {}

local floor = math.floor

local function errorf(level, ...)
	if type(level) == "number" then
		return error(string.format(...), level + 1)
	else -- level is actually the format string.
		return error(string.format(level, ...), 2)
	end
end

local function binary_range_search(codepoint, ranges)
	local low, mid, high
	low, high = 1, ranges.length or require "Module:TableTools".length(ranges)
	while low <= high do
		mid = floor((low + high) / 2)
		local range = ranges[mid]
		if codepoint < range[1] then
			high = mid - 1
		elseif codepoint <= range[2] then
			return range, mid
		else
			low = mid + 1
		end
	end
	return nil, mid
end
p.binary_range_search = binary_range_search

--[[
local function linear_range_search(codepoint, ranges)
	for i, range in ipairs(ranges) do
		if range[1] <= codepoint and codepoint <= range[2] then
			return range
		end
	end
end
--]]

-- Load a module by indexing "loader" with the name of the module minus the
-- "Module:Unicode data/" part. For instance, loader.blocks returns
-- [[Module:Unicode data/blocks]]. If a module cannot be loaded, false will be
-- returned.
local loader = setmetatable({}, {
	__index = function (self, key)
		local success, data = pcall(mw.loadData, "Module:Unicode data/" .. key)
		if not success then
			data = false
		end
		self[key] = data
		return data
	end
})

-- For the algorithm used to generate Hangul Syllable names,
-- see "Hangul Syllable Name Generation" in section 3.12 of the
-- Unicode Specification:
-- https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf
local name_hooks = {
	{     0x00,     0x1F, "<control-%04X>" }, -- C0 control characters
	{     0x7F,     0x9F, "<control-%04X>" }, -- DEL and C1 control characters
	{   0x3400,   0x4DBF, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension A
	{   0x4E00,   0x9FFF, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph
	{   0xAC00,   0xD7A3, function (codepoint) -- Hangul Syllables
		local Hangul_data = loader.Hangul
		local syllable_index = codepoint - 0xAC00

		return ("HANGUL SYLLABLE %s%s%s"):format(
			Hangul_data.leads[floor(syllable_index / Hangul_data.final_count)],
			Hangul_data.vowels[floor((syllable_index % Hangul_data.final_count)
				/ Hangul_data.trail_count)],
			Hangul_data.trails[syllable_index % Hangul_data.trail_count]
		)
	end },
	-- High Surrogates, High Private Use Surrogates, Low Surrogates
	{   0xD800,   0xDFFF, "<surrogate-%04X>" },
	{   0xE000,   0xF8FF, "<private-use-%04X>" }, -- Private Use
	-- CJK Compatibility Ideographs
	{   0xF900,   0xFA6D, "CJK COMPATIBILITY IDEOGRAPH-%04X" },
	{   0xFA70,   0xFAD9, "CJK COMPATIBILITY IDEOGRAPH-%04X" },
	{  0x17000,  0x187F7, "TANGUT IDEOGRAPH-%04X" }, -- Tangut Ideograph
	{  0x18800,  0x18AFF, function (codepoint)
		return ("TANGUT COMPONENT-%03d"):format(codepoint - 0x187FF)
	end },
	{  0x18D00,  0x18D08, "TANGUT IDEOGRAPH-%04X" }, -- Tangut Ideograph Supplement
	{  0x1B170,  0x1B2FB, "NUSHU CHARACTER-%04X" }, -- Nushu
	{  0x20000,  0x2A6DF, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension B
	{  0x2A700,  0x2B739, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension C
	{  0x2B740,  0x2B81D, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension D
	{  0x2B820,  0x2CEA1, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension E
	{  0x2CEB0,  0x2EBE0, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension F
	-- CJK Compatibility Ideographs Supplement (Supplementary Ideographic Plane)
	{  0x2F800,  0x2FA1D, "CJK COMPATIBILITY IDEOGRAPH-%04X" },
	{  0xE0100,  0xE01EF, function (codepoint) -- Variation Selectors Supplement
		return ("VARIATION SELECTOR-%d"):format(codepoint - 0xE0100 + 17)
	end},
	{  0x30000,  0x3134A, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension G
	{  0x31350,  0x323AF, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension H
	{  0x2EBF0,  0x2EE5D, "CJK UNIFIED IDEOGRAPH-%04X" }, -- CJK Ideograph Extension I
	{  0xF0000,  0xFFFFD, "<private-use-%04X>" }, -- Plane 15 Private Use
	{ 0x100000, 0x10FFFD, "<private-use-%04X>" }  -- Plane 16 Private Use
}
name_hooks.length = #name_hooks

local name_range_cache

local function generate_name(data, codepoint)
	if type(data) == "string" then
		return data:format(codepoint)
	else
		return data(codepoint)
	end
end

--[[
-- Checks that the code point is a number and in range.
-- Does not check whether code point is an integer.
-- Not used
local function check_codepoint(funcName, argIdx, val)
	require 'libraryUtil'.checkType(funcName, argIdx, val, 'number')
	if codepoint < 0 or 0x10FFFF < codepoint then
		errorf("Codepoint %04X out of range", codepoint)
	end
end
--]]

-- https://www.unicode.org/versions/Unicode11.0.0/ch04.pdf, section 4.8
function p.lookup_name(codepoint)
	-- U+FDD0-U+FDEF and all code points ending in FFFE or FFFF are Unassigned
	-- (Cn) and specifically noncharacters:
	-- https://www.unicode.org/faq/private_use.html#nonchar4
	if 0xFDD0 <= codepoint and (codepoint <= 0xFDEF
			or floor(codepoint % 0x10000) >= 0xFFFE) then
		return ("<noncharacter-%04X>"):format(codepoint)
	end

	if name_range_cache -- Check if previously used "name hook" applies to this code point.
			and codepoint >= name_range_cache[1]
			and codepoint <= name_range_cache[2] then
		return generate_name(name_range_cache[3], codepoint)
	end
	
	local range = binary_range_search(codepoint, name_hooks)
	if range then
		name_range_cache = range
		return generate_name(range[3], codepoint)
	end

	local data = loader[('names/%03X'):format(codepoint / 0x1000)]
	
	if data and data[codepoint] then
		return data[codepoint]
	
	-- Unassigned (Cn) consists of noncharacters and reserved characters.
	-- The character has been established not to be a noncharacter,
	-- and if it were assigned, its name would already been retrieved,
	-- so it must be reserved.
	else
		return ("<reserved-%04X>"):format(codepoint)
	end
end

function p.lookup_image(codepoint)
	local data = loader[('images/%03X'):format(codepoint / 0x1000)]
	
	if data then
		return data[codepoint]
	end
end

local planes = {
	[ 0] = "Basic Multilingual Plane";
	[ 1] = "Supplementary Multilingual Plane";
	[ 2] = "Supplementary Ideographic Plane";
	[ 3] = "Tertiary Ideographic Plane";
	[14] = "Supplementary Special-purpose Plane";
	[15] = "Supplementary Private Use Area-A";
	[16] = "Supplementary Private Use Area-B";
}

-- Load [[Module:Unicode data/blocks]] if needed and assign it to this variable.
local blocks

local function block_iter(blocks, i)
	i = i + 1
	local data = blocks[i]
	if data then
		 -- Unpack doesn't work on tables loaded with mw.loadData.
		return i, data[1], data[2], data[3]
	end
end

-- An ipairs-type iterator generator for the list of blocks.
function p.enum_blocks()
	local blocks = loader.blocks
	return block_iter, blocks, 0
end

function p.lookup_plane(codepoint)
	local i = floor(codepoint / 0x10000)
	return planes[i] or ("Plane %u"):format(i)
end

function p.lookup_block(codepoint)
	local blocks = loader.blocks
	local range = binary_range_search(codepoint, blocks)
	if range then
		return range[3]
	else
		return "No Block"
	end
end

function p.get_block_info(name)
	for i, block in ipairs(loader.blocks) do
		if block[3] == name then
			return block
		end
	end
end

function p.is_valid_pagename(pagename)
	local has_nonws = false

	for cp in mw.ustring.gcodepoint(pagename) do
		if (cp == 0x0023) -- #
		or (cp == 0x005B) -- [
		or (cp == 0x005D) -- ]
		or (cp == 0x007B) -- {
		or (cp == 0x007C) -- |
		or (cp == 0x007D) -- }
		or (cp == 0x180E) -- MONGOLIAN VOWEL SEPARATOR
		or ((cp >= 0x2000) and (cp <= 0x200A)) -- spaces in General Punctuation block
		or (cp == 0xFFFD) -- REPLACEMENT CHARACTER
		then
			return false
		end

		local printable, result = p.is_printable(cp)
		if not printable then
			return false
		end

		if result ~= "space-separator" then
			has_nonws = true
		end
	end

	return has_nonws
end

local function manual_unpack(what, from)
	if what[from + 1] == nil then
		return what[from]
	end
	
	local result = {}
	from = from or 1
	for i, item in ipairs(what) do
		if i >= from then
			table.insert(result, item)
		end
	end
	return unpack(result)
end

local function compare_ranges(range1, range2)
	return range1[1] < range2[1]
end

-- Creates a function to look up data in a module that contains "singles" (a
-- code point-to-data map) and "ranges" (an array containing arrays that contain
-- the low and high code points of a range and the data associated with that
-- range).
-- "loader" loads and returns the "singles" and "ranges" tables.
-- "match_func" is passed the code point and either the data or the "dots", and
-- generates the final result of the function.
-- The varargs ("dots") describes the default data to be returned if there wasn't
-- a match.
-- In case the function is used more than once, "cache" saves ranges that have
-- already been found to match, or a range whose data is the default if there
-- was no match.
local function memo_lookup(data_module_subpage, match_func, ...)
	local dots = { ... }
	local cache = {}
	local singles, ranges

	return function (codepoint)
		if not singles then
			local data_module = loader[data_module_subpage]
			singles, ranges = data_module.singles, data_module.ranges
		end

		if singles[codepoint] then
			return match_func(codepoint, singles[codepoint])
		end

		local range = binary_range_search(codepoint, cache)
		if range then
			return match_func(codepoint, manual_unpack(range, 3))
		end
		
		local range, index = binary_range_search(codepoint, ranges)
		if range then
			table.insert(cache, range)
			table.sort(cache, compare_ranges)
			return match_func(codepoint, manual_unpack(range, 3))
		end
		
		if ranges[index] then
			local dots_range
			if codepoint > ranges[index][2] then
				dots_range = {
					ranges[index][2] + 1,
					ranges[index + 1] and ranges[index + 1][1] - 1 or 0x10FFFF,
					unpack(dots)
				}
			else -- codepoint < range[index][1]
				dots_range = {
					ranges[index - 1] and ranges[index - 1][2] + 1 or 0,
					ranges[index][1] - 1,
					unpack(dots)
				}
			end
			table.sort(cache, compare_ranges)
		end
		
		return match_func(codepoint)
	end
end

-- Get a code point's combining class value in [[Module:Unicode data/combining]],
-- and return whether this value is not zero. Zero is assigned as the default
-- if the combining class value is not found in this data module.
-- That is, return true if character is combining, or false if it is not.
-- See https://www.unicode.org/reports/tr44/#Canonical_Combining_Class_Values for
-- more information.
p.is_combining = memo_lookup(
	"combining",
	function (codepoint, combining_class)
		return combining_class and combining_class ~= 0 or false
	end,
	0)

function p.add_dotted_circle(str)
	return (mw.ustring.gsub(str, ".",
		function(char)
			if p.is_combining(mw.ustring.codepoint(char)) then
				return '◌' .. char
			end
		end))
end

local lookup_control = memo_lookup(
	"control",
	function (codepoint, ccc)
		return ccc or "assigned"
	end,
	"assigned")
p.lookup_control = lookup_control

function p.is_assigned(codepoint)
	return lookup_control(codepoint) ~= "unassigned"
end

function p.is_printable(codepoint)
	local result = lookup_control(codepoint)
	return (result == "assigned") or (result == "space-separator"), result
end

function p.is_whitespace(codepoint)
	local result = lookup_control(codepoint)
	return (result == "space-separator"), result
end

p.lookup_category = memo_lookup(
	"category",
	function (codepoint, category)
		return category
	end,
	"Cn")

local lookup_script = memo_lookup(
	"scripts",
	function (codepoint, script_code)
		return script_code or 'Zzzz'
	end,
	"Zzzz")
p.lookup_script = lookup_script

function p.get_best_script(str)
	-- Check type of argument, because mw.text.decode coerces numbers to strings!
	require "libraryUtil".checkType("get_best_script", 1, str, "string")
	
	-- Convert HTML character references (including named character references,
	-- or character entities) to characters.
	str = mw.text.decode(str, true)
	
	local scripts = {}
	for codepoint in mw.ustring.gcodepoint(str) do
		local script = lookup_script(codepoint)
		
		-- Ignore "Inherited", "Undetermined", or "Uncoded" scripts.
		if not (script == "Zyyy" or script == "Zinh" or script == "Zzzz") then
			scripts[script] = true
		end
	end
	
	-- If scripts does not contain two or more keys,
	-- return first and only key (script code) in table.
	if not next(scripts, next(scripts)) then
		return next(scripts)
	end -- else return majority script, or else "Zzzz"?
end

function p.is_Latin(str)
	require "libraryUtil".checkType("get_best_script", 1, str, "string")
	str = mw.text.decode(str, true)
	
	-- Search for the leading bytes that introduce the UTF-8 encoding of the
	-- code points U+0340-U+10FFFF. If they are not found and there is at least
	-- one Latin-script character, the string counts as Latin, because the rest
	-- of the characters can only be Zyyy, Zinh, and Zzzz.
	-- The only scripts found below U+0370 (the first code point of the Greek
	-- and Coptic block) are Latn, Zyyy, Zinh, and Zzzz.
	-- See the codepage in the [[UTF-8]] article.
	if not str:find "[\205-\244]" then
		for codepoint in mw.ustring.gcodepoint(str) do
			if lookup_script(codepoint) == "Latn" then
				return true
			end
		end
	end
	
	local Latn = false
	
	for codepoint in mw.ustring.gcodepoint(str) do
		local script = lookup_script(codepoint)
		
		if script == "Latn" then
			Latn = true
		elseif not (script == "Zyyy" or script == "Zinh"
				or script == "Zzzz") then
			return false
		end
	end
	
	return Latn
end

-- Checks that a string contains only characters belonging to right-to-left
-- scripts, or characters of ignorable scripts.
function p.is_rtl(str)
	require "libraryUtil".checkType("get_best_script", 1, str, "string")
	str = mw.text.decode(str, true)
	
	-- Search for the leading bytes that introduce the UTF-8 encoding of the
	-- code points U+0580-U+10FFFF. If they are not found, the string can only
	-- have characters from a left-to-right script, because the first code point
	-- in a right-to-left script is U+0591, in the Hebrew block.
	if not str:find "[\214-\244]" then
		return false
	end
	
	local result = false
	local rtl = loader.scripts.rtl
	for codepoint in mw.ustring.gcodepoint(str) do
		local script = lookup_script(codepoint)
		
		if rtl[script] then
			result = true
		elseif not (script == "Zyyy" or script == "Zinh"
				or script == "Zzzz") then
			return false
		end
	end
	
	return result
end


--[[--------------------------< I S _ R T L _ F R A M E >------------------------------------------------------

external entry from an {{#invoke:}} to determine if a string of text is rtl.  Strips html and html-like tags so
that those tags don't corrupt the is-rtl-is-not-rtl determination; this added for the cases where the rtl text
has <br /> tags.

]]

function p.is_rtl_frame (frame)
	local str = frame.args[1];													-- get the string from the {{#invoke:}} frame
	str = str:gsub ('%b<>', '');												-- strip any html and html-like tags
	return p.is_rtl (str);														-- return if whatever remains rtl; false else
end


local function get_codepoint(args, arg)
	local codepoint_string = args[arg]
		or errorf(2, "Parameter %s is required", tostring(arg))
	local codepoint = tonumber(codepoint_string, 16)
		or errorf(2, "Parameter %s is not a code point in hexadecimal base",
			tostring(arg))
	if not (0 <= codepoint and codepoint <= 0x10FFFF) then
		errorf(2, "code point in parameter %s out of range", tostring(arg))
	end
	return codepoint
end

local function get_func(args, arg, prefix)
	local suffix = args[arg]
		or errorf(2, "Parameter %s is required", tostring(arg))
	suffix = mw.text.trim(suffix)
	local func_name = prefix .. suffix
	local func = p[func_name]
		or errorf(2, "There is no function '%s'", func_name)
	return func
end

-- This function allows any of the "lookup" functions to be invoked. The first
-- parameter is the word after "lookup_"; the second parameter is the code point
-- in hexadecimal base.
function p.lookup(frame)
	local func = get_func(frame.args, 1, "lookup_")
	local codepoint = get_codepoint(frame.args, 2)
	local result = func(codepoint)
	if func == p.lookup_name then
		-- Prevent code point labels such as <control-0000> from being
		-- interpreted as HTML tags.
		result = result:gsub("<", "&lt;")
	end
	return result
end

function p.is(frame)
	local func = get_func(frame.args, 1, "is_")
	
	-- is_Latin and is_valid_pagename take strings.
	if func == p.is_Latin or func == p.is_valid_pagename or func == p.is_rtl then
		return (func(frame.args[2]))
	else -- The rest take code points.
		local codepoint = get_codepoint(frame.args, 2)
		return (func(codepoint)) -- Adjust to one result.
	end
end

return p