Module:Convert

-- TODO Too many items to list, but following are some points: - Output needs  rather than space in several places. - Some conversions require two outputs: 55 nmi. - Some units have two values: 3.21 m. - Remove commas from input numbers; add to output (always?). - Use U+2212 MINUS SIGN for input + output number, not '-'. --

---BEGIN DATA TABLE- Plan to write a program to generate the conversion tables below. The input would be a text file in human-friendly format, and the output would be the following tables. When a lot of data is added, it might be useful to put this in another module. Values from http://en.wikipedia.org/wiki/Conversion_of_units Check with http://en.wikipedia.org/wiki/Template:Convert/list_of_units --

local SIprefixes = { ['Y'] = 24, ['Z'] = 21, ['E'] = 18, ['P'] = 15, ['T'] = 12, ['G'] =  9, ['M'] =  6, ['k'] =  3, ['H'] =  2, ['da'] = 1, ['D'] =  1,  -- Not an SI prefix, but allow for people typing this. ['d'] = -1, ['c'] = -2, ['m'] = -3, ['µ'] = -6, ['u'] = -6,  -- Not an SI prefix, but allow for people typing this. ['n'] = -9, ['p'] = -12, ['f'] = -15, ['a'] = -18, ['z'] = -21, ['y'] = -24 } local units = { lookup = function (self, unit) -- If unit is known, return its converter table. local t = self[unit] if t ~= nil then return t end -- This could be done in a much more exciting, Luaist, way with a metatable. for prefix,exponent in pairs(SIprefixes) do           local plen = prefix:len if #unit > plen and prefix == unit:sub(1,0+plen) then local baseunit = unit:sub(plen+1,-1) local baset = self[baseunit] if baset ~= nil and baset.prefixes == true then t = mw.clone(baset) t[2] = t[2] * 10 ^ exponent end end end local msg = 'Unit %s not known' error(msg:format(unit)) end, utype = 1, scale = 2, offset = 3, defaultunit = 4, ['g'] =  {'mass',        1000,       0,      'lb',     prefixes = true}, ['lb'] = {'mass',        0.45359237, 0,      'kg'}, ['m'] =  {'length',      1,          0,      'ft',     prefixes = true}, ['m'] =  {'length',      1,          0,      'mi',     prefixes = true}, ['m'] =  {'length',      1,          0,      'in',     prefixes = true}, ['mi'] = {'length',      1609.344,   0,      'km'}, ['ft'] = {'length',      0.3048,     0,      'm'}, ['in'] = {'length',      0.0254,     0,      'cm'}, ['K'] =  {'temperature', 1,          273.15, 'C'}, ['C'] =  {'temperature', 1,          0,      'F'}, ['F'] =  {'temperature', 5/9,        32,     'C'}, ['°K'] = {'temperature', 1,          273.15, '°C'}, ['°C'] = {'temperature', 1,          0,      '°F'}, ['°F'] = {'temperature', 5/9,        32,     '°C'}, } ---END DATA TABLE-

-- Configuration options to keep magic values in one location. local config = {}

local function get_config(frame) -- Return table of configuration options. -- Unclear if this is currently needed, but it may help if adapting -- code for a different wiki. local cfg = {} -- Following settings are defaults that can be overridden by template. cfg.numdot = '.'       -- decimal mark before fractional digits cfg.numsep = ','       -- thousands separator for numbers (',', '.', or nil) for k,v in frame:argumentPairs do       cfg[k] = v          -- arguments from template's     end -- Following settings are mandatory (to limit abuse). cfg.maxsigfig = 20     -- maximum number of significant figures return cfg end

local function withseparator(text) -- Return string for a number with thousand separators inserted. -- Parameter text is a string like "-12345" or "12345.6789". -- Separator is inserted only in the integer part (not in fraction). -- Four-digit integer parts have a separator (like "1,234"). local numsep = config.numsep if #numsep == 0 then return text end local function insert(text, first, last) local result = '' while last >= first do           if last >= first + 3 then result = numsep .. text:sub(last-2, last) .. result last = last - 3 else return text:sub(first, last) .. result end end return result end local first = 1 local sign = text:sub(first, 1) if sign == '+' or sign == '-' then -- To handle Unicode minus (multibyte), perhaps use following: -- first = text:find('%d') first = 2 else sign = '' end local last = text:find(config.numdot, first, true) if last == nil then last = #text else last = last - 1 end return sign .. insert(text, first, last) .. text:sub(last+1) end

local function formatnumber(value, sigfig) -- Return result of converting number 'value' to a string, -- rounded to 'sigfig' significant figures. local format = string.format local rep = string.rep local sign = '' local numdot = config.numdot local function zeropad(text, dot) count = sigfig - #text if count <= 0 then return text end return text .. dot .. rep('0', count) end if sigfig <= 0 then sigfig = 1 elseif sigfig > config.maxsigfig then sigfig = config.maxsigfig end if value == 0 then return zeropad('0', numdot) end if value < 0 then sign = '-' -- need proper Unicode minus value = -value end local digits local exp, frac = math.modf(math.log10(value)) if frac == 0 then -- Value 1 gives frac = 0, and 0.1 gives frac = -0 (negative zero). digits = zeropad('1', '') exp = exp + 1 -- adjust so dot is before digits else local prec = sigfig if value > 1 then prec = prec - 1 -- will be one sig fig before dot end digits = format(format('%%.%df', prec), 10^frac) if value < 1 then -- Is MediaWiki run in a locale where following might be '0,'? assert(digits:sub(1, 2) == '0.', 'Bug: rounded number not 0.xxx') digits = digits:sub(3) else if prec == 0 then assert(digits:find(numdot, 1, true) == nil, 'Bug: unexpected dot') else assert(digits:sub(2, 2) == numdot, 'Bug: rounded number not x.xxx') digits = digits:sub(1, 1) .. digits:sub(3) end exp = exp + 1 -- adjust so dot is before digits end end if exp >= #digits then digits = digits .. rep('0', exp - #digits) -- result has no dot elseif exp <= 0 then digits = '0' .. numdot .. rep('0', -exp) .. digits else digits = digits:sub(1, exp) .. numdot .. digits:sub(exp+1) end return sign .. digits end

local function require_number(value, missing, invalid) -- If value is missing or not a number, throw an error. -- Thousand separators (valid or not) are first removed. -- Return value as a number if valid. if value == nil then error(missing) end if type(value) == 'number' then return value end local numsep = config.numsep if #numsep > 0 then value = string.gsub(value, numsep, '') end local number = tonumber(value) if number == nil then error(invalid:format(value)) end return number end

local function require_integer(value, missing, invalid) -- If value is missing or not an integer, throw an error. -- Return value as a number if valid. local number = require_number(value, missing, invalid) if number ~= math.floor(number) then error(invalid:format(value)) end return number end

local function get_parms(pframe) -- Return table with all arguments passed by template converted to   -- named arguments. The numeric args are used to add named args: --  in_text, in_text2 (strings given for value, value2) --  value, in_unit, out_unit, value2, range, round_to -- (except for range, which is nil or a table, the named args that are   -- added here could be provided by the user of the template). local range_types = { -- text to separate input, output ranges ['and'] = {' and ', ' and '}, ['by'] = {' by ', ' by '}, ['to'] = {' to ', ' to '}, ['-'] = {'–', '–'},       ['to(-)'] = {' to ', '–'}, ['x'] = {' by ', ' × '}, ['+/-'] = {' ± ', ' ± '},   }    local args = {}                         -- arguments passed to template for k,v in pframe:argumentPairs do       args[k] = v    end args.in_text = args[1] args.value = require_number(args.in_text, 'Need value', 'Value "%s" must be a number') local in_unit = args[2] local i = 3 local range = range_types[in_unit] if range ~= nil then args.in_text2 = args[3] args.value2 = require_number(args.in_text2, 'Need second value', 'Second value "%s" must be a number') in_unit = args[4] i = 5 end local out_unit = args[i] local round_to = args[i+1] if in_unit == nil then error('Need input unit') end args.in_unit = in_unit args.out_unit = out_unit args.range = range args.round_to = args.round_to or round_to -- allow named parameter return args end

local function default_roundto(intext, factor) -- Return a default value for round_to (an integer like 2, 0, -2). -- prec = (precision implied in intext) --     = (#digits after dot, or negative of #zeroes before dot) -- If conversion is multiplication by a factor, and -- if factor >= 0.02, compensate prec by adding N where: --    N    factor is in range --    1     .02  :   .2   =    .1/5 :   .1*2    --     0     .2   :   2    =    1/5  :   1*2    --    -1     2    :  20    =   10/5  :  10*2    --    -2    20    : 200    =  100/5  : 100*2  etc. -- TODO Exception required for temperature. prec = 0 dot = intext:find('.', 1, true) if dot ~= nil then prec = intext:sub(dot+1):len if prec == 0 then intext = intext:sub(1, -2) end end if prec == 0 then prec = -intext:match('0*$'):len end if factor ~= nil and factor >= 0.02 then prec = prec - math.floor(math.log10(factor*5)) end return prec end

local function scaled(value, in_unit, out_unit) -- Return scaled value for a simple convert. return (value - in_unit[units.offset]) * (in_unit[units.scale] / out_unit[units.scale]) + out_unit[units.offset] end

local function cvtround(invalue, intext, parms) -- Convert given invalue using parms (return '' if invalue == nil). -- Return rounded, formatted string for result, using rounding -- specified in parms. -- This code combines convert/round because some rounding requires -- knowledge of what we are converting. -- TODO Lots of checking required. Will need tweaks for special cases -- handled by old Template:Convert. -- TODO Limit values to avoid abuse (for example, can currently set   -- round_to to very large values like 999). local text = '' if invalue == nil then return text end local outvalue = scaled(invalue, parms.in_unit_table, parms.out_unit_table) local round_to = parms.round_to local sigfig = parms.sigfig local disp = parms.disp local auto = false if round_to then -- Ignore sigfig, disp. round_to = require_integer(round_to, 'Need value', 'round_to "%s" must be an integer') elseif sigfig then -- Ignore disp. sigfig = require_integer(sigfig, 'Need value', 'sigfig "%s" must be an integer') if sigfig <= 0 then msg = 'sigfig "%s" must be positive' error(msg:format(parms.sigfig)) end text = formatnumber(outvalue, sigfig) elseif disp == '5' then local negative = false if outvalue < 0 then negative = true outvalue = -outvalue end outvalue = math.floor((outvalue / 5) + 0.5) * 5 if negative then outvalue = -outvalue end text = string.format('%.0f', outvalue) else auto = true -- using default rounding -- TODO If conversion is not multiplication by a number, need factor = nil. local factor = outvalue / invalue round_to = default_roundto(intext, factor) end if round_to then if round_to >= 0 then if auto then -- TODO No less than two significant figures. end local fmt = '%.' .. string.format('%.0f', round_to) .. 'f'           text = string.format(fmt, outvalue) else -- This always keeps two sig figs. Should that be done if not auto? round_to = -round_to -- #digits that want to zero local maxzeroes = 0 -- maximum #digits that should be zeroed if outvalue > 100 then maxzeroes = math.log10(outvalue) - 1 end if round_to > maxzeroes then round_to = maxzeroes end if round_to > 0 then local scaled = string.format('%.0f', outvalue/(10^round_to)) text = scaled .. string.rep('0', round_to) else -- TODO Not satisfactory? Should limit sigfigs? text = string.format('%f', outvalue) end end end return withseparator(text) end

local disp_single = { ['or'] = '%s %s or %s %s', ['sqbr'] = '%s %s [%s %s]', ['comma'] = '%s %s, %s %s', ['b'] = '%s %s (%s %s)', }

local disp_double = { ['or'] = '%s%s%s %s or %s%s%s %s', ['sqbr'] = '%s%s%s %s [%s%s%s %s]', ['comma'] = '%s%s%s %s, %s%s%s %s', ['b'] = '%s%s%s %s (%s%s%s %s)', }

local function process(parms) -- If we can convert from given in to out unit, return the table values for the two given unit types. parms.in_unit_table = units:lookup(parms.in_unit) if parms.out_unit == nil then          -- need to catch empty string also? parms.out_unit = parms.in_unit_table[units.defaultunit] end parms.out_unit_table = units:lookup(parms.out_unit) if parms.in_unit_table[units.utype] ~= parms.out_unit_table[units.utype] then local msg = 'Cannot convert %s to %s' error(msg:format(parms.in_unit_table[units.utype], parms.out_unit_table[units.utype])) end local intext = parms.in_text local intext2 = parms.in_text2 local outext = cvtround(parms.value, intext, parms) local outext2 = cvtround(parms.value2, intext2, parms) local range = parms.range local disp = parms.disp local wikitext intext = withseparator(intext) -- TODO what if intext already has commas? if range == nil then wikitext = disp_single[disp] or disp_single['b'] wikitext = wikitext:format(intext, parms.in_unit, outext, parms.out_unit) else wikitext = disp_double[disp] or disp_double['b'] wikitext = wikitext:format(intext, range[1], intext2, parms.in_unit, outext, range[2], outext2, parms.out_unit) end return wikitext end

-- Used by template. -- We will have to keep old undefined undefined for a long time, and run -- in parallel with undefined undefined while testing/developing. local p = {} local bodge = require "Module:mw" -- This fixes up mw.text.tag for us.

function p.convert(frame) config = get_config(frame) local pframe = frame:getParent local parms = get_parms(pframe) local state,text = pcall(process, parms) if not state then local params = {style="color:black; background-color:orange;"} text=mw.text.tag({name="span", contents="Conversion error: " .. text, params=params}) end return text end

return p