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Revision as of 17:03, 22 October 2019

This is the module sandbox page for Module:Formatnum (diff). See also the companion subpage for test cases (run).

This module provides a number formatting function. This function can be used from #invoke or from other Lua modules.

This module is used by Module:Complex date

Use from other Lua modules

To use the module from normal wiki pages, no special preparation is needed. If you are using the module from another Lua module, first you need to load it, like this:

local mf = require('Module:Formatnum')

(The mf variable stands for Module Formatnum; you can choose something more descriptive if you prefer.)

Most functions in the module have a version for Lua and a version for #invoke. It is possible to use the #invoke functions from other Lua modules, but using the Lua functions has the advantage that you do not need to access a Lua frame object. Lua functions are preceded by _, whereas #invoke functions are not.

main

{{#invoke:Formatnum|main|x|lang=|prec=|sep=}}

mf.formatNum(x, lang, prec, sep)

See also

-- This module is intended to replace the functionality of Template:Formatnum and related templates. 
local p = {}

function p.main(frame)
	local args = frame:getParent().args
	if not args and not args.number then
		args = frame.args
	end
	local prec    = args.prec or ''
	local sep     = args.sep or ''
	local number  = args or args.number or ''
	local lang    = args or args.lang or ''
	-- validate the language parameter within MediaWiki's caller frame
	if lang:lower() == "none" then
		-- no language, so do nothing
	elseif lang == "arabic-indic" then -- only for back-compatibility ("arabic-indic" is not a SupportedLanguage)
		lang = "fa" -- better support than "ks"
	elseif lang == '' or not mw.language.isSupportedLanguage(lang) then
		-- Note that 'SupportedLanguages' are not necessarily 'BuiltinValidCodes', and so they are not necessarily
		-- 'KnownLanguages' (with a language name defined at least in the default localisation of the local wiki).
		-- But they all are ValidLanguageCodes (suitable as Wiki subpages or identifiers: no slash, colon, HTML tags, or entities)
		-- In addition, they do not contain any capital letter in order to be unique in page titles (restriction inexistant in BCP47),
		-- but they may violate the standard format of BCP47 language tags for specific needs in MediaWiki.
		-- Empty/unspecified and unsupported languages are treated here in Commons using the user's language,
		-- instead of the local 'ContentLanguage' of the Wiki.
		lang = frame:callParserFunction( "int", "lang" ) -- get user's chosen language
		if not mw.language.isSupportedLanguage(lang) then
			lang = mw.language.getContentLanguage()
		end
	end
	return p.formatNum(number, lang, prec, sep ~= '')
end

local digit = { -- substitution of decimal digits for languages not supported by mw.language:formatNum() in core Lua libraries for MediaWiki
	 = { '൦', '൧', '൨', '൩', '൪', '൫', '൬', '൭', '൮', '൯' },
	     = { '᠐', '᠑', '᠒', '᠓', '᠔', '᠕', '᠖', '᠗', '᠘', '᠙'},
	     = { '௦', '௧', '௨', '௩', '௪', '௫', '௬', '௭', '௮', '௯'},
	     = { '౦', '౧', '౨', '౩', '౪', '౫', '౬', '౭', '౮', '౯'},
	     = { '๐', '๑', '๒', '๓', '๔', '๕', '๖', '๗', '๘', '๙'}
}

function p.formatNum(number, lang, prec, compact)
	-- Do not alter the specified value when it is not a valid number, return it as is
	local value = tonumber(number)
	if value == nil then
		return number
	end
	-- Basic ASCII-only formatting (without paddings)
	number = tostring(value)

	-- Check the presence of an exponent (incorrectly managed in mw.language:FormatNum() and even forgotten due to an internal bug, e.g. in Hindi)
	local exponent
	local pos = string.find(number, '')
	if pos ~= nil then
		exponent = string.sub(number, pos + 1, string.len(number))
		number = string.sub(number, 1, pos - 1)
	else
		exponent = ''
	end

	-- Check the minimum precision requested
	prec = tonumber(prec) -- nil if not specified as a true number
	if prec ~= nil then
		prec = math.floor(prec)
		if prec < 0 then
			prec = nil -- discard an incorrect precision (not a positive integer)
		elseif prec > 14 then
			prec = 14 -- maximum precision supported by tostring(number)
		end
	end

	-- Preprocess the minimum precision in the ASCII string
	local dot
	if (prec or 0) > 0 then
		pos = string.find(number, '.', 1, true) -- plain search, no regexp
		if pos ~= nil then
			prec = pos + prec - string.len(number) -- effective number of trailing decimals to add or remove
			dot = '' -- already present
		else
			dot = '.' -- must be added
		end
	else
		dot = '' -- don't add dot
		prec = 0 -- don't alter the precision
	end
	
	if lang ~= nil and mw.language.isKnownLanguageTag(lang) == true then
	    -- Convert number to localized digits, decimal separator, and group separators
	    local language = mw.getLanguage(lang)
	    if compact then
			number = language:formatNum(tonumber(number), { noCommafy = 'y' }) -- caveat: can load localized resources for up to 20 languages
	    else
			number = language:formatNum(tonumber(number)) -- caveat: can load localized resources for up to 20 languages
	    end
	    -- Postprocessing the precision
	    if prec > 0 then
			local zero = language:formatNum(0)
			number = number .. dot .. mw.ustring.rep(zero, prec)
	    elseif prec < 0 then
			-- TODO: rounding of last decimal; here only truncate decimals in excess
			number = mw.ustring.sub(number, 1, mw.ustring.len(number) + prec)
	    end
	    -- Append the localized base-10 exponent without grouping separators (there's no reliable way to detect a localized leading symbol 'E')
	    if exponent ~= '' then
			number = number .. 'E' .. language:formatNum(tonumber(exponent),{noCommafy=true})
	    end
	else -- not localized, ASCII only
		-- Postprocessing the precision
		if prec > 0 then
			number = number .. dot .. mw.string.rep('0', prec)
		elseif prec < 0 then
			-- TODO: rounding of last decimal; here only truncate decimals in excess
			number = mw.string.sub(number, 1, mw.string.len(number) + prec)
		end
		-- Append the base-10 exponent
		if exponent ~= '' then
			number = number .. 'E' .. exponent
		end
	end

	-- Special cases for substitution of ASCII digits (missing support in Lua core libraries for some languages)
	if digit then
		for i, v in ipairs(digit) do
			number = mw.ustring.gsub(number, tostring(i - 1), v)
		end
	end

	return number
end

return p

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