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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
    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 == "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
    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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