Module:BaseConvert

Converts numbers to a specified base between 2 and 36, for use in templates such as {{binary}}, {{octal}}, {{hexadecimal}}, etc.

Usage

local BaseConvert = require('Module:BaseConvert')
BaseConvert.convert({n = 14600926, base = 16}) -- returns 'DECADE'

Arguments:

• n - (required) the number to be converted, as a string. It may be a number instead, if the input base is 10.
• base - (required) the base to which the number should be converted. May be between 2 and 36, inclusive.
• from - the base of the input. Defaults to 10 (or 16 if the input has a leading '0x'). Note that bases other than 10 are not supported if the input has a fractional part.
• precision - number of digits to be rendered after the radix point. Trailing zeros will be added if needed. If not specified, however many digits are needed will be shown, up to 10.
• width - minimum number of digits to be rendered before the radix point. Leading zeros will be added if needed.
• default - Value to return if n is empty or non-numeric. Defaults to the value of n.
• prefix / suffix - wikitext to add before/after the returned result. Will not be added if n is empty or non-numeric. For example, you might use a prefix of 0x when converting to hex, or a suffix of <sub>8</sub> when converting to octal.

From templates

In wikimarkup, this module may be called with a function name ntom, e.g.:

Markup	Renders as
{{#invoke:BaseConvert|16to10| FF }}	255
{{#invoke:BaseConvert|10to36|500}}	DW
{{#invoke:BaseConvert|10to16|Foo|default=0}}	0

All options above are supported, excluding |base=, |from= and |n= which are set by the mandatory options. You may also call convert which is near-identical to the Lua form above.

---

local p = {}

local digits = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'

local function normalizeFullWidthChars(s)
	return mw.ustring.gsub(s, '[！-～]', function(s)
		return mw.ustring.char(mw.ustring.codepoint(s, 1) - 0xFEE0)
	end)
end

local function _convert(n, base, from, precision, width, default, prefix, suffix)
	n = tostring(n)

	-- strip off any leading '0x' (unless x is a valid digit in the input base)
	from = tonumber(from)
	if not from or from < 34 then
		local c
		n, c = n:gsub('^(-?)0[Xx]', '%1')
		if c > 0 and not from then from = 16 end
	end

	-- check for a negative sign. Do this while the input is still in string form,
	-- because tonumber doesn't support negative numbers in non-10 bases.
	local sign = ''
	local c
	n, c = n:gsub('^-', '')
	if c > 0 then sign = '-' end

	-- replace any full-width Unicode characters in the string with their ASCII equivalents
	n = normalizeFullWidthChars(n)

	-- handle scientific notation with whitespace around the 'e' e.g. '5 e7'
	n = n:gsub('%s*[eE]%s*', 'e')

	from = from or 10
	local num = tonumber(n, from)
	base = tonumber(base)
	precision = tonumber(precision)
	width = tonumber(width)

	if not num or not base then return default or n end

	local i, f = math.modf(num)

	local t = {}
	repeat
		local d = (i % base) + 1
		i = math.floor(i / base)
		table.insert(t, 1, digits:sub(d, d))
	until i == 0
	while #t < (width or 0) do
		table.insert(t, 1, '0')
	end
	local intPart = table.concat(t, '')

	-- compute the fractional part
	local tf = {}
	while f > 0 and #tf < (precision or 10) do
		f = f * base
		i, f = math.modf(f)
		table.insert(tf, digits:sub(i + 1, i + 1))
	end

	-- add trailing zeros if needed
	if precision and #tf < precision then
		for i = 1, precision - #tf do
			table.insert(tf, '0')
		end
	end

	local fracPart = table.concat(tf, '')

	-- remove trailing zeros if not needed
	if not precision then
		fracPart = fracPart:gsub('0*$', '')
	end

	-- add the radix point if needed
	if #fracPart > 0 then
		fracPart = '.' .. fracPart
	end

	return (prefix or '') .. sign .. intPart .. fracPart .. (suffix or '')
end

function p.convert(frame)
	-- Allow for invocation via #invoke or directly from another module
	local args
	if frame == mw.getCurrentFrame() then
		args = frame.args
	else
		args = frame
	end

	local n = args.n
	local base = args.base
	local from = args.from
	local precision = args.precision
	local width = args.width
	local default = args.default
	local prefix = args.prefix
	local suffix = args.suffix
	return _convert(n, base, from, precision, width, default, prefix, suffix)
end

setmetatable(p, {
	__index = function(t, k)
		local from, base = k:match('^([0-9]+)to([0-9]+)$')
		if not from then return nil end
		return function(frame)
			local args = frame.args
			return _convert(mw.text.trim(args[1]), base, from, args.precision, args.width,
				args.default, args.prefix, args.suffix)
		end
	end
})

return p