Module:Convert/makeunits
The purpose of this module is to prepare the data used by Module:Convert to allow conversion between units of measurement.
Usage: Put one of the following lines (with nothing else) in a sandbox:
{{#invoke:convert/makeunits|makeunits}}{{subst:#invoke:convert/makeunits|makeunits}}
Previewing the sandbox should display the wikitext that needs to be copied and pasted into Module:Convert/data. If a problem occurs, warning messages will be displayed to indicate that the unit definitions need to be fixed.
By default, the module reads the unit definitions from Module:Convert/documentation/conversion data. For testing purposes, it is possible to specify that the definitions are read from another page, for example, User:Johnuniq/sandbox2, by specifying the wanted title:
{{#invoke:convert/makeunits|makeunits|User:Johnuniq/sandbox2}}{{subst:#invoke:convert/makeunits|makeunits|User:Johnuniq/sandbox2}}
The module contains table specials which is used to insert a small amount of "built-in" data that is not currently defined in the input wikitext.
The module reads data from Module:Convert/text to allow localization of the table of units for use on another wiki.
--[==[ makeunits.lua
This script can be run on a stand-alone computer to generate the table
of units that specifies how conversions are performed by Module:Convert.
LATER:
If support additional currencies, need to update table:
local currency = { ['$'] = true, ['£'] = true }
Procedure:
* Copy the Lua script of [[Module:Convert/makeunits]] to a local file
(say file makeunits.lua).
* Copy the Lua script of [[Module:Convert/text]] to a local file
(say file converttext.lua).
* Copy the wikitext of the units specification to a local file
(say file wikitable.tmp which is the default name for the input).
* Run this script with command-line arguments:
makeunits.lua converttext.lua wikitable.tmp
* Output is written to a file (default name is makeunits.tmp).
* Copy the output into Module:Convert/data to replace the previous table.
Script method:
* Read lines, ignoring everything before "== Conversions ==".
* Process the following lines:
* Find next level-3 heading like "=== Length ===".
* Parse each following line starting with "|"
(but ignore lines starting with "|-" or "|}".
* Split such lines into fields (delimiter "||") and trim
leading/trailing whitespace from each field.
Remove any "colspan" at front of second field (symbol).
* Remove thousand separators (commas) from the scale field.
If the scale is a number, do not change it.
Otherwise, it should be an expression like "5/9", in
which case it is replaced by the value of the expression.
* Remove wiki formatting '[[...]]' from the link field.
* Remove redundant fields from the unit to reduce size of data file.
* Create alternative forms of a unit such as an alias or a combination.
* Stop processing when encounter end of file or a line starting
with a level-2 heading ("==" but not "===").
* Repeat above for each heading listed at prepare_data().
* Output Lua source for the units table.
-- Output has the following form.
local all_units = {
["unitcode"] = { -- standard format
name1 = "singular name", -- omitted if redundant
name1_us = "singular name sp=us", -- omitted if redundant
name2 = "plural name", -- omitted if redundant
name2_us = "plural name sp=us", -- omitted if redundant
symbol = "symbol",
sym_us = "symbol sp=us", -- omitted if redundant
usename = 1, -- omitted if empty
utype = "unit type", -- from level-3 heading
scale = 1, -- a value, if necessary from evaluating an expression
subdivs = { ["ft"] = { 5280, default = "km" }, ["yd"] = { 1760 } } -- composite input; omitted if empty
link = "title of article for wikilink", -- omitted if empty or redundant
... -- other values
},
["unitcode"] = { -- alternative format to generate an alias
target = "unit code",
... -- optional values to override those of target
},
["unitcode"] = { -- alternative format to generate a "per" unit like $/acre or BTU/h
per = {u1, u2}, -- numbered table of unitcodes (u1 may be a currency symbol)
... -- optional values
},
["unitcode"] = { -- alternative format to generate an error message
shouldbe = "message that some other unit code should be used",
},
["unitcode"] = { -- alternative format for combination outputs (like 'm ft')
combination = {u1, u2, ...}, -- numbered table of unitcodes
utype = "unit type", -- as for standard format
},
["unitcode"] = { -- alternative format for output multiples (like 'ftin')
combination = {u1, u2, ...}, -- numbered table of unitcodes
multiple = {f1, f2, ...}, -- numbered table of integer factors
utype = "unit type", -- as for standard format
},
...
}
]==]
-- To make updating Module:Convert/data easier, this script inserts a preamble and
-- a postamble so the result is what needs to be uploaded.
local file_preamble = [==[
--[[ Conversion data used by Module:Convert.
Use mw.loadData() to obtain read-only access to this module so that
it is loaded only once per page.
These data tables follow:
all_units all properties for a unit, including default output
default_exceptions exceptions for default output ('kg' and 'g' have different defaults)
link_exceptions exceptions for links ('kg' and 'g' have different links)
These tables are generated by a script which reads the wikitext of a page
that documents the required properties of each unit.
The wiki page is currently:
http://en.wikipedia.org/wiki/User:Johnuniq/Conversion_data
]]
]==]
local file_postamble = [==[
return {
all_units = all_units,
default_exceptions = default_exceptions,
link_exceptions = link_exceptions,
}
]==]
local specials = {
-- This table is used to add extra fields when defining some units which
-- require exceptions to normal processing.
-- Each key is in the local language, while each value is fixed text,
-- however, this script is NOT edited to localize the keys. Instead,
-- [[Module:Convert/text]] is edited, and this script replaces sections
-- of the following with localized definitions, if given.
-- LATER: It would be better if this was defined in the conversions table.
utype = {
-- ["unit type in local language"] = "name_used_in_this_script"
["fuel efficiency"] = "type_fuel_efficiency",
["length"] = "type_length",
["temperature"] = "type_temperature",
["volume"] = "type_volume",
},
ucode = {
exception = {
-- ["unit code in local language"] = "name_used_in_module_convert"
["ft"] = "integer_more_precision",
["in"] = "subunit_more_precision",
},
istemperature = {
-- Common temperature scales (not keVT or MK).
-- ["unit code in local language"] = 1
["C"] = true,
["F"] = true,
["K"] = true,
["R"] = true,
},
usesymbol = {
-- Use unit symbol not name if abbr not specified.
-- ["unit code in local language"] = 1
["C"] = 1,
["F"] = 1,
["K"] = 1,
["R"] = 1,
["C-change"] = 1,
["F-change"] = 1,
["K-change"] = 1,
},
alttype = {
-- Unit has an alternate type that is valid conversion.
-- ["unit code in local language"] = "alternate type in local language"
["Nm"] = "energy",
["ftlb"] = "torque",
["ftlb-f"] = "torque",
["ftlbf"] = "torque",
["inlb"] = "torque",
["inlb-f"] = "torque",
["inlbf"] = "torque",
["inoz-f"] = "torque",
["inozf"] = "torque",
},
},
}
---Begin code from Convert----------------------------------------------
-- Following is adapted from Module:Convert.
local SIprefixes, eng_scales
local plural_suffix = 's'
local function shallow_copy(t)
-- Return a shallow copy of t.
-- Do not need the features and overhead of mw.clone() provided by Scribunto.
local result = {}
for k, v in pairs(t) do
result[k] = v
end
return result
end
local unit_mt = {
-- Metatable to get missing values for a unit that does not accept SI prefixes,
-- or a for a unit that accepts prefixes but where no prefix was used.
-- In the latter case, and before use, fields symbol, name1, name1_us
-- must be set from _symbol, _name1, _name1_us respectively.
__index = function (self, key)
local value
if key == 'name1' or key == 'sym_us' then
value = self.symbol
elseif key == 'name2' then
value = self.name1 .. plural_suffix
elseif key == 'name1_us' then
value = self.name1
if not rawget(self, 'name2_us') then
-- If name1_us is 'foot', do not make name2_us by appending plural_suffix.
self.name2_us = self.name2
end
elseif key == 'name2_us' then
local raw1_us = rawget(self, 'name1_us')
if raw1_us then
value = raw1_us .. plural_suffix
else
value = self.name2
end
elseif key == 'link' then
value = self.name1
else
return nil
end
rawset(self, key, value)
return value
end
}
local unit_prefixed_mt = {
-- Metatable to get missing values for a unit that accepts SI prefixes,
-- and where a prefix has been used.
-- Before use, fields si_name, si_prefix must be defined.
__index = function (self, key)
local value
if key == 'symbol' then
value = self.si_prefix .. self._symbol
elseif key == 'sym_us' then
value = self.symbol -- always the same as sym_us for prefixed units
elseif key == 'name1' then
local pos = rawget(self, 'prefix_position') or 1
value = self._name1
value = value:sub(1, pos - 1) .. self.si_name .. value:sub(pos)
elseif key == 'name2' then
value = self.name1 .. plural_suffix
elseif key == 'name1_us' then
value = rawget(self, '_name1_us')
if value then
local pos = rawget(self, 'prefix_position') or 1
value = value:sub(1, pos - 1) .. self.si_name .. value:sub(pos)
else
value = self.name1
end
elseif key == 'name2_us' then
if rawget(self, '_name1_us') then
value = self.name1_us .. plural_suffix
else
value = self.name2
end
elseif key == 'link' then
value = self.name1
else
return nil
end
rawset(self, key, value)
return value
end
}
local function lookup(units, unitcode, sp, what)
-- Return a copy of the unit if found, or return nil.
-- In this cut-down code, sp is always nil, and what is ignored.
local t = units[unitcode]
if t then
if t.shouldbe then
return nil
end
local result = shallow_copy(t)
if result.prefixes then
result.symbol = result._symbol
result.name1 = result._name1
result.name1_us = result._name1_us
end
return setmetatable(result, unit_mt)
end
for plen = 2, 1, -1 do
-- Look for an SI prefix; should never occur with an alias.
-- Check for longer prefix first ('dam' is decametre).
-- Micro (µ) is two bytes in utf-8, so is found with plen = 2.
local prefix = string.sub(unitcode, 1, plen)
local si = SIprefixes[prefix]
if si then
local t = units[unitcode:sub(plen+1)]
if t and t.prefixes then
local result = shallow_copy(t)
if (sp == 'us' or t.sp_us) and si.name_us then
result.si_name = si.name_us
else
result.si_name = si.name
end
result.si_prefix = si.prefix or prefix
-- In this script, each scale is a string.
result.scale = tostring(tonumber(t.scale) * 10 ^ (si.exponent * t.prefixes))
result.prefixes = nil -- a prefixed unit does not take more prefixes (in this script, the returned unit may be added to the list of units)
return setmetatable(result, unit_prefixed_mt)
end
end
end
local exponent, baseunit = unitcode:match('^e(%d+)(.*)')
if exponent then
local engscale = eng_scales[exponent]
if engscale then
local result = lookup(units, baseunit, sp, 'no_combination')
if not result then return nil end
if result.engscale == nil then
result.defkey = unitcode -- key to lookup default exception
engscale.exponent = exponent
result.engscale = engscale
-- Do not set result.scale as this code is called for units where that is not set.
return result
end
end
end
return nil
end
local function evaluate_condition(value, condition)
-- Return true or false from applying a conditional expression to value,
-- or throw an error if invalid.
-- A very limited set of expressions is supported:
-- v < 9
-- v * 9 < 9
-- where
-- 'v' is replaced with value
-- 9 is any number (as defined by Lua tonumber)
-- '<' can also be '<=' or '>' or '>='
-- In addition, the following form is supported:
-- LHS and RHS
-- where
-- LHS, RHS = any of above expressions.
local function compare(value, text)
local arithop, factor, compop, limit = text:match('^%s*v%s*([*]?)(.-)([<>]=?)(.*)$')
if arithop == nil then
error('Invalid default expression', 0)
elseif arithop == '*' then
factor = tonumber(factor)
if factor == nil then
error('Invalid default expression', 0)
end
value = value * factor
end
limit = tonumber(limit)
if limit == nil then
error('Invalid default expression', 0)
end
if compop == '<' then
return value < limit
elseif compop == '<=' then
return value <= limit
elseif compop == '>' then
return value > limit
elseif compop == '>=' then
return value >= limit
end
error('Invalid default expression', 0) -- should not occur
end
local lhs, rhs = condition:match('^(.-%W)and(%W.*)')
if lhs == nil then
return compare(value, condition)
end
return compare(value, lhs) and compare(value, rhs)
end
---End code from Convert------------------------------------------------
local function strip(text)
-- Return text with no leading/trailing whitespace.
return text:match("^%s*(.-)%s*$")
end
local function empty(text)
-- Return true if text is nil or empty (assuming a string).
return text == nil or text == ''
end
local function readlines(filename, trim)
-- Return a table of lines read from a file (line endings removed).
-- Trim trailing whitespace from each line (if trim = 1), or
-- trim leading and trailing whitespace (if trim = 2).
-- Throw an error if a problem occurs.
local pattern
if trim == 1 then
pattern = '^(.-)%s*$'
elseif trim == 2 then
pattern = '^%s*(.-)%s*$'
end
local f = io.open(filename, 'r')
if f == nil then
error('Could not open file ' .. filename, 0)
end
local lines = {}
for line in f:lines() do
if pattern then
line = line:match(pattern)
end
table.insert(lines, line)
end
f:close()
return lines
end
-- Tables of units: k = unit code, v = unit table.
local units_index = {} -- all units: normal, alias, per, combination, or multiple
local alias_index = {} -- all aliases (to detect attempts to define more than once)
local per_index = {} -- all "per" units (to detect attempts to define more than once)
local function get_unit(ucode)
-- Look up unit code in our cache of units.
if empty(ucode) then
return nil
end
return lookup(units_index, ucode)
end
local overrides = {} -- read from input file for unit codes that should not be checked for a duplicate
local function insert_unique_unit(data, unit, index)
-- After inserting any required built-in data, insert the unit into the
-- data table and (if index not nil) add to index,
-- but not if the unit code is already defined.
local ucode = unit.unitcode
local known = get_unit(ucode)
if known and not overrides[ucode] then
error('Unit code "' .. ucode .. '" has already been defined', 0)
end
for item, t in pairs(specials.ucode) do
unit[item] = t[ucode]
end
if index then
index[ucode] = unit
end
table.insert(data, unit)
end
local function check_condition(condition)
-- Return true if condition appears to be valid; otherwise return false.
for _, value in ipairs({ 0, 0.1, 1, 1.1, 10, 100, 1000, 1e4, 1e5 }) do
local success, result = pcall(evaluate_condition, value, condition)
if not success then
return false
end
end
return true
end
local function check_default_expression(default, ucode)
-- Return a numbered table of names present in param default
-- (two names if an expression, or one name (param default) otherwise).
-- Throw an error if a problem occurs.
-- An expression uses pipe-delimited fields with 'v' representing
-- the input value for the conversion.
-- Example (suffix is optional): 'v < 120 ! small ! big ! suffix'
-- returns { 'smallsuffix', 'bigsuffix' }.
if default:find('!', 1, true) == nil then
return { default }
end
local t = {}
for item in (default .. '!'):gmatch('%s*(.-)%s*!') do
t[#t+1] = item -- split on '!', removing leading/trailing whitespace
end
if not (#t == 3 or #t == 4) then
error('Default output "' .. default .. '" for unit "' .. ucode .. '" should have 2 or 3 "!"', 0)
end
local condition, default1, default2 = t[1], t[2], t[3]
if #t == 4 then
default1 = default1 .. t[4]
default2 = default2 .. t[4]
end
if not check_condition(condition) then
error('Invalid condition in default "' .. default .. '" for unit "' .. ucode .. '"', 0)
end
return { default1, default2 }
end
local function check_default(default, ucode, utype, unit_table)
-- Check the given name (or expression) of a default output.
-- Throw an error if a problem occurs.
for _, default in ipairs(check_default_expression(default, ucode)) do
local default_table = get_unit(default)
if default_table == nil then
error('Default output "' .. default .. '" for unit "' .. ucode .. '" is not defined', 0)
end
if not (utype == unit_table.utype and utype == default_table.utype) then
error('Default output "' .. default .. '" for unit "' .. ucode .. '" has wrong type', 0)
end
end
end
local function check_all_defaults(units, maxerrors)
-- Check each default in units and warn if needed.
-- This is done after all input data has been processed.
-- Throw an error if a problem occurs.
local errors = {}
local missing = {} -- unitcodes with missing defaults
for _, unit in ipairs(units) do
if unit.shouldbe == nil and unit.combination == nil then
-- This is a standard unit or an alias/per (not shouldbe, combo).
-- An alias may have a default defined, but it is optional.
local default = unit.default
local ucode = unit.unitcode
if empty(default) then
if unit.target == nil then -- unit should have a default
table.insert(missing, ucode)
end
else
local ok, msg = pcall(check_default, default, ucode, unit.utype, unit)
if not ok then
table.insert(errors, msg)
if #errors >= maxerrors then
break
end
end
end
end
end
if #errors > 0 then
error(table.concat(errors, '\n'), 0)
end
if #missing > 0 then
print('Warning: Units with the following unit codes have no default output.')
local limit = maxerrors
for _, v in ipairs(missing) do
limit = limit - 1
if limit < 0 then
print(' (and more not shown)')
break
end
print(' ' .. v)
end
end
end
local function check_all_pers(units, maxerrors)
-- Check each component of each "per" unit and warn if needed.
-- In addition, add any required extra fields for some types of units.
-- This is done after all input data has been processed.
-- Throw an error if a problem occurs.
local currency = { ['$'] = true, ['£'] = true }
local errors = {}
local function errmsg(text)
table.insert(errors, text)
end
for _, unit in ipairs(units) do
local per = unit.per
if per then
local ucode = unit.unitcode
if #per ~= 2 then
errmsg('Unit "' .. ucode .. '" does not have exactly 2 fields in the "per"')
else
local types = {}
for i, v in ipairs(per) do
if empty(v) then
errmsg('Unit "' .. ucode .. '" has an empty field in the "per"')
end
if not currency[v] then
local t = get_unit(v)
if t then
types[i] = t.utype
else
errmsg('Unit "' .. ucode .. '" has undefined unit code "' .. v .. '" in the "per"')
end
end
end
if specials.utype[unit.utype] == 'type_fuel_efficiency' then
local expected = { type_volume = 1, type_length = 2 }
local top_type = expected[specials.utype[types[1]]]
local bot_type = expected[specials.utype[types[2]]]
if top_type and bot_type and top_type ~= bot_type then
unit.iscomplex = true
if top_type == 1 then
unit.invert = 1
else
unit.invert = -1
end
else
errmsg('Unit "' .. ucode .. '" has invalid unit types for fuel efficiency')
end
end
end
end
if #errors >= maxerrors then
break
end
end
if #errors > 0 then
error(table.concat(errors, '\n'), 0)
end
end
local function update_units(units, composites)
-- Update some unit definitions with extra data defined in other sections.
-- This is done after all input data has been processed.
for _, unit in ipairs(units) do
local comp = composites[unit.unitcode]
if comp then
unit.subdivs = '{ ' .. table.concat(comp.subdivs, ', ') .. ' }'
end
end
end
local function make_override(data)
-- Return a function which, when called, stores a unit code is not to be
-- checked for a duplicate. The table is stored in data (also a table).
return function (utype, fields)
local ucode = fields[1]
if ucode == nil then
error('Missing unit code for an override', 0)
end
if data[ucode] then
error('Override "' .. ucode .. '" is already defined', 0)
end
data[ucode] = true
end
end
local function make_default(data)
-- Return a function which, when called, stores a table that defines a
-- default output unit. The table is stored in data (also a table).
local defaults_index = {} -- to detect attempts to define a default twice
return function (utype, fields)
-- Store a table defining a unit.
-- This is for a unit such as 'kg' that has a default output unit
-- different from what is defined for the base unit ('g').
-- Throw an error if a problem occurs.
local ucode = fields[1]
local default = fields[2]
if empty(ucode) then
error('Defaults section: no unit code specified', 0)
end
if empty(default) then
error('Defaults section: unit "' .. ucode .. '" has no default specified', 0)
end
if #fields ~= 2 then
error('Defaults section: unit "' .. ucode .. '" should have two fields only', 0)
end
local unit_table = get_unit(ucode)
if unit_table == nil then
error('Defaults section: unit "' .. ucode .. '" is not defined', 0)
end
local symbol = unit_table.defkey or unit_table.symbol
if empty(symbol) then
error('Defaults section: unit "' .. ucode .. '" must have a symbol', 0)
end
check_default(default, ucode, utype, unit_table)
if defaults_index[ucode] then
error('Defaults section: unit "' .. ucode .. '" has already been specified', 0)
end
defaults_index[ucode] = default
table.insert(data, { symbol = symbol, default = default })
end
end
local function clean_link(link, name)
-- Return link, customary where:
-- link = given link after removing any '[[...]]' wiki formatting
-- and removing any leading '+' or '*' or '@';
-- customary = 1 if leading '+', or 2 if '*' or 3 if '@', or nil
-- (for extra "US" or "U.S." or "Imperial" customary units link).
-- Result has leading/trailing whitespace removed, and is nil if empty
-- or if link matches the name, if a name is specified.
-- If the resulting link is nil, no link field is stored, and
-- if a link is required, it will be set from the unit's name.
if empty(link) then
return nil
end
local prefixes = { ['+'] = 1, ['*'] = 2, ['@'] = 3 }
local customary = prefixes[link:sub(1, 1)]
if customary then
link = strip(link:sub(2))
end
if link:sub(1, 2) == '[[' then
link = link:sub(3)
end
if link:sub(-2) == ']]' then
link = link:sub(1, -3)
end
link = strip(link)
if link == '' then
link = nil
elseif name then
local l = link:sub(1, 1):lower() .. link:sub(2)
local n = name:sub(1, 1):lower() .. name:sub(2)
if l == n then
link = nil -- link == name, ignoring case of first letter
end
end
return link, customary
end
local function make_link(data)
-- Return a function which, when called, stores a table that defines a
-- link exception. The table is stored in data (also a table).
local links_index = {} -- to detect attempts to define a link twice
return function (utype, fields)
-- Store a table defining a unit.
-- This is for a unit such as 'kg' that has a linked article
-- different from what is defined for the base unit ('g').
-- Throw an error if a problem occurs.
local ucode = fields[1]
local link = clean_link(fields[2])
if empty(ucode) then
error('Missing unit code for a link', 0)
end
if empty(link) then
error('No link defined for unit "' .. ucode .. '"', 0)
end
if #fields ~= 2 then
error('Row for unit "' .. ucode .. '" link should have two fields only', 0)
end
local unit_table = get_unit(ucode)
if unit_table == nil then
error('Unit code "' .. ucode .. '" for a link is not defined', 0)
end
local symbol = unit_table.symbol
if empty(symbol) then
error('Unit code "' .. ucode .. '" for a link must have a symbol', 0)
end
if links_index[ucode] then
error('Link exception "' .. ucode .. '" is already defined', 0)
end
links_index[ucode] = link
table.insert(data, { symbol = symbol, link = link })
end
end
local function clean_scale(scale)
-- Return cleaned scale as a string, after evaluating any expression.
-- It would be better to retain scale expressions like "5/9" so that
-- the expression is evaluated on the server and maintains the full
-- resolution of the server. However, there are many such expressions
-- in the table of all units, and it seems pointless to require the
-- server to evaluate all of them just to do one convert.
if empty(scale) then
error('Missing scale', 0)
end
assert(type(scale) == 'string', 'Bug: scale has an unexpected type')
scale = string.gsub(scale, ',', '') -- remove comma separators
if tonumber(scale) then -- not an expression
return scale
end
-- Do some simple sanity checks to avoid executing rubbish.
if #scale > 50 then
error('Scale is too long: "' .. scale .. '"', 0)
end
if string.len(scale:gsub('[ %d%-*/+()^eE.]+', '')) > 0 then
error('Scale expression contains invalid characters: "' .. scale .. '"', 0)
end
local status, value = pcall(loadstring('return (' .. scale .. ')'))
if not (status and type(value) == 'number') then
error('Scale expression is invalid: "' .. scale .. '"', 0)
end
local result = string.format('%.30g', value)
if result:find('#', 1, true) then
-- Overflow or similar (scale = '1/0' gives result = '1.#INF').
error('Scale expression gives an invalid value: "' .. scale .. '"', 0)
end
-- Omit redundant zeros from results like '1.2e-005'.
-- Do not bother looking for results like '1.2e+005' as none occur in practice.
local lhs, zeros, rhs = result:match('^(.-e%-)(0+)(.*)')
if zeros then
result = lhs .. rhs
end
return result
end
local function add_alias_optional_fields(unit, start, fields, target)
-- Inspect fields[i] for i = start, start+1 ..., and extract any
-- definitions appropriate for an alias or "per", and add them to unit.
-- For an alias, target is a valid unit; for a "per", target is nil.
-- Throw error if encounter an invalid entry.
for i = start, #fields do
local field = fields[i]
if not empty(field) then
local lhs, rhs = field:match('^%s*(.-)%s*=%s*(.-)%s*$')
local good
if not empty(rhs) then
for _, item in ipairs({ 'sp', 'default', 'link', 'multiplier', 'symbol', 'symlink' }) do
if lhs == item then
if item == 'sp' then
if rhs == 'us' then
unit.sp_us = true
good = true
end
elseif item == 'link' then
local tlink
if target then
tlink = target[item]
end
local link, customary = clean_link(rhs, tlink)
if link then
unit[item] = link
end
if customary then
unit.customary = customary
end
good = true
elseif item == 'symlink' then
local pos1 = rhs:find('[[', 1, true)
local pos2 = rhs:find(']]', 1, true)
if not (pos1 and pos2 and (pos1 < pos2)) then
error('Alias "' .. unit.unitcode .. '" must include a wikilink ("[[...]]") in the symlink text', 0)
end
unit.symlink = rhs
good = true
elseif item == 'multiplier' then
if not tonumber(rhs) then
error('Alias "' .. unit.unitcode .. '" has multiplier "' .. rhs .. '" which is not a number', 0)
end
unit[item] = rhs
good = true
else
if target and rhs == target[item] then
error('Should omit "' .. item .. '" for alias "' .. unit.unitcode .. '" because it is the same as its target', 0)
end
unit[item] = rhs
good = true
end
break
end
end
end
if not good then
error('Alias has invalid text in field "' .. field .. '"', 0)
end
end
end
end
local function make_alias(fields, ucode, utype, symbol)
-- Return a new alias unit, or return nil if symbol is not already
-- defined as the unit code of the target unit.
-- Throw an error if invalid.
local target = get_unit(symbol)
if not target then
return nil
end
local unit = { unitcode = ucode, utype = utype, target = symbol }
add_alias_optional_fields(unit, 3, fields, target)
if alias_index[ucode] then
error('Alias "' .. ucode .. '" already defined', 0)
else
alias_index[ucode] = unit
end
if target.utype ~= utype then
error('Target of alias "' .. ucode .. '" has wrong type', 0)
end
return unit
end
local function make_per(fields, ucode, utype, symbol)
-- Return a new "per" unit, or return nil if symbol is not of form "x/y".
-- Throw an error if invalid.
-- The top, bottom unit codes are checked later, after all units are defined.
local top, bottom = symbol:match('^(.-)/(.*)$')
if not top then
return nil
end
local unit = { unitcode = ucode, utype = utype, per = { strip(top), strip(bottom) } }
add_alias_optional_fields(unit, 3, fields)
if per_index[ucode] then
error('Per unit "' .. ucode .. '" already defined', 0)
else
per_index[ucode] = unit
end
return unit
end
local function make_unit(data)
-- Return a function which, when called, stores a table that defines a
-- single unit. The table is stored in data (also a table).
local fieldnames = {
-- Fields in the Conversions section are assumed to be in the following order.
'unitcode',
'symbol',
'sym_us',
'scale',
'extra',
'name1',
'name2',
'name1_us',
'name2_us',
'prefixes',
'default',
'link',
}
return function (utype, fields)
-- Store a table defining a unit.
-- Throw an error if a problem occurs.
local ucode, symbol = fields[1], fields[2]
if empty(utype) then
error('Missing unit type', 0)
end
if empty(ucode) then
error('Missing unit code', 0)
end
if empty(symbol) then
error('Missing symbol', 0)
end
local prefix = symbol:sub(1, 1)
if prefix == '~' or prefix == '=' or prefix == '!' then
if symbol:sub(1, 2) == '==' then
prefix = symbol:sub(1, 2)
end
symbol = strip(symbol:sub(#prefix + 1)) -- omit prefix and any following whitespace
fields[2] = symbol
else
prefix = nil -- not a valid prefix
end
if prefix == '=' or prefix == '==' then
-- ucode is an alias (a fake unit code used in a convert template), or
-- defines a "per" unit like "$/acre" or "BTU/h".
-- For an alias, symbol is the unit code of the actual unit.
-- For a "per", symbol is of form "x/y" where x and y are unit codes,
-- or x is a recognized currency symbol and y is a unit code.
-- Checking that x and y are valid is deferred until all units have
-- been defined so, for example, "BTU/h" can be defined before "h".
local unit
if prefix == '=' then
unit = make_alias(fields, ucode, utype, symbol)
else
unit = make_per(fields, ucode, utype, symbol)
end
if not unit then
-- Do not define an alias in terms of another alias.
error('Primary unit must be defined before alias =' .. symbol, 0)
end
insert_unique_unit(data, unit, units_index)
return
elseif prefix == '!' then
-- ucode may be incorrectly entered as a unit code.
-- symbol is a message saying what unit code should be used.
local unit = { unitcode = ucode, shouldbe = symbol }
insert_unique_unit(data, unit, nil)
return
end
-- Make the unit.
local unit = { utype = utype }
for i, name in ipairs(fieldnames) do
if not empty(fields[i]) then
unit[name] = fields[i]
end
end
-- Remove redundancy from unit.
if unit.sym_us == symbol then
unit.sym_us = nil
end
local prefixes = unit.prefixes
if empty(prefixes) then
prefixes = nil
end
local name1, name2 = unit.name1, unit.name2
if name1 then
if name1 == symbol and not prefixes then
-- A unit which takes an SI prefix must not have a nil name because,
-- for example, the name for "kW" = "kilo" .. "watt" (name for "W").
-- The "not prefixes" test is needed for bn.wikipedia where the
-- watt unit has the same name and symbol.
unit.name1 = nil
end
else
name1 = symbol
end
if name2 then
if plural_suffix ~= '' and name2 == name1 .. plural_suffix then
unit.name2 = nil
end
end
local name1_us, name2_us = unit.name1_us, unit.name2_us
if name1_us then
if name1_us == name1 then
unit.name1_us = nil
end
else
name1_us = name1
end
if name2_us then
if plural_suffix ~= '' and name2_us == name1_us .. plural_suffix then
unit.name2_us = nil
end
end
-- Other changes to unit.
unit.scale = clean_scale(unit.scale)
local extra = unit.extra
if not empty(extra) then
-- Set appropriate fields for a unit that needs more than a simple
-- multiplication by a ratio of unit scales to convert values.
unit.iscomplex = true
if extra == 'volume/length' then
unit.invert = 1
elseif extra == 'length/volume' then
unit.invert = -1
elseif specials.utype[utype] == 'type_temperature' then
unit.offset = extra
else
unit.builtin = extra
end
end
if prefix == '~' then
-- Magic code for units like "acre" where the symbol is not really a
-- symbol, and output should use the singular or plural name instead.
unit.usename = 1
end
local name_for_link
if prefixes then
-- If set name_for_link = name1 for a prefixed unit like g, then the
-- link is "kilogram" for kg, and "yottagram" for Yg, and so on for all
-- prefixes. That might be good for some units, but not all.
if prefixes == 'SI' then
unit.prefixes = 1
elseif prefixes == 'SI2' then
unit.prefixes = 2
elseif prefixes == 'SI3' then
unit.prefixes = 3
else
error('Unknown prefix: "' .. prefixes .. '"', 0)
end
else
name_for_link = name1
end
unit.link, unit.customary = clean_link(unit.link, name_for_link)
if prefixes then
local name1, name1_us = unit.name1, unit.name1_us -- after redundancy removed
if name1 == nil then
error('Unit with Prefix set must include Name', 0)
end
if unit.name2 or unit.name2_us then
error('Unit with Prefix set must have plural name that is Name + "s"', 0)
end
if unit.sym_us then
error('Unit with Prefix set must have same Symbol and US symbol', 0)
end
local pos = name1:find('%s', 1, true)
local pos_us
if name1_us then
pos_us = name1_us:find('%s', 1, true)
else
pos_us = pos
end
if pos ~= pos_us then
-- The only cases with "%s" are "square %smetre" and "cubic %smetre" (or "meter" for US),
-- so do not bother having a procedure to handle different positions of "%s".
error('Unit with Prefix set and "%s" in Name and US name, must have the "%s" at the same position', 0)
end
if pos then
if pos == 1 then
-- Omit leading "%s"; convert will assume position = 1 since not stored.
unit.name1 = name1:sub(3)
if name1_us then
unit.name1_us = name1_us:sub(3)
end
else
-- Omit "%s" and store its position.
unit.name1 = name1:sub(1, pos - 1) .. name1:sub(pos + 2)
if name1_us then
unit.name1_us = name1_us:sub(1, pos - 1) .. name1_us:sub(pos + 2)
end
unit.prefix_position = pos
end
end
for _, name in ipairs({ 'symbol', 'name1', 'name1_us' }) do
unit['_' .. name] = unit[name]
unit[name] = nil -- force call to __index metamethod so any SI prefix can be handled
end
end
for name, v in pairs(unit) do
-- Reject if a string field includes "%s" (should never occur after above).
if type(v) == 'string' and v:find('%s', 1, true) then
error('Field "' .. name .. '" must not contain "%s"', 0)
end
end
insert_unique_unit(data, unit, units_index)
end
end
local function make_combination(data)
-- Return a function which, when called, stores a table that defines a
-- single combination unit. The table is stored in data (also a table).
return function (utype, fields)
-- Store a table defining a unit.
-- This is for a combination unit that specifies more than one output.
-- The target units must be defined first.
-- Throw an error if a problem occurs.
local unit = { utype = utype, combination = {} }
for i, v in ipairs(fields) do
if i == 1 then -- unitcode
if v == '' then
error('Missing unit code for a combination', 0)
end
unit.unitcode = v
elseif v == '' then
-- Ignore empty fields.
else
local target = get_unit(v)
if target == nil then
error('Unit "' .. v .. '" in combination "' .. unit.unitcode .. '" not defined', 0)
end
if target.utype ~= utype then
error('Unit "' .. v .. '" in combination "' .. unit.unitcode .. '" has wrong type', 0)
end
table.insert(unit.combination, v)
end
end
if #unit.combination < 2 then
local msg
if #unit.combination == 0 then
msg = 'No units specified for combination "' .. unit.unitcode .. '"'
else
msg = 'Only one unit specified for combination "' .. unit.unitcode .. '"'
end
error(msg, 0)
end
insert_unique_unit(data, unit, units_index)
end
end
local function reversed(t)
-- Return a numbered table in reverse order.
local reversed, count = {}, #t
for i = 1, count do
reversed[i] = t[count + 1 - i]
end
return reversed
end
local function make_inputmultiple(data)
-- Return a function which, when called, stores a table that defines a
-- single composite (multiple input) unit. The table is stored in data (also a table).
return function (utype, fields)
-- Set or update an entry in the data table to record that a unit
-- accepts subdivisions to make a composite input unit like '|2|ft|6|in'.
-- The target units must be defined first.
-- Throw an error if a problem occurs.
local unitcode -- dummy code required for simplicity, but which is not used in output
local alternate_code -- an alternative unit code can be specified to replace convert input
local fixed_name -- a fixed name can be specified to replace the unit's normal symbol/name
local default_code
local ucodes, scales = {}, {}
for i, v in ipairs(fields) do
-- 1=composite, 2=ucode1, 3=ucode2, 4=default, 5=alternate, 6=name
if i == 1 then
if v == '' then
error('Missing unit code for a composite', 0)
end
unitcode = v
elseif 2 <= i and i <= 5 then
if not (i == 5 and v == '') then
local target = get_unit(v)
if target == nil then
error('Unit "' .. v .. '" in composite "' .. unitcode .. '" not defined', 0)
end
if target.utype ~= utype then
error('Unit "' .. v .. '" in composite "' .. unitcode .. '" has wrong type', 0)
end
if i < 4 then
table.insert(ucodes, v)
table.insert(scales, target.scale)
elseif i == 4 then
default_code = v
else
if scales[#scales] ~= target.scale then
error('Alternate unit "' .. v .. '" in composite "' .. unitcode .. '" has wrong scale', 0)
end
alternate_code = v
end
end
elseif i == 6 then
if v ~= '' then
fixed_name = v
end
else
error('Composite "' .. unitcode .. '" has too many fields', 0)
end
end
if #ucodes ~= 2 then
error('Composite "' .. unitcode .. '" must specify exactly two unit codes', 0)
end
if default_code == nil then
error('Composite "' .. unitcode .. '" must specify a default unit code', 0)
end
-- Component units must be specified from most-significant to least-significant,
-- and each ratio of a pair of scales must be very close to an integer.
-- Currently, there will be exactly two scales and one ratio.
local ratios, count = {}, #scales
for i = 1, count do
local scale = tonumber(scales[i])
if scale == nil or scale <= 0 then
error('Composite "' .. unitcode .. '" has a component with an invalid scale, "' .. scales[i] .. '"', 0)
end
scales[i] = scale
end
for i = 1, count - 1 do
local ratio = scales[i] / scales[i + 1]
local rounded = math.floor(ratio + 0.5)
if rounded < 2 then
error('Composite "' .. unitcode .. '" has components in wrong order or with invalid scales', 0)
end
if math.abs(ratio - rounded)/ratio > 1e-6 then
error('Composite "' .. unitcode .. '" has components where scale ratios are not integers', 0)
end
ratios[i] = rounded
end
local text = { tostring(ratios[1]) }
local function add_text(key, value)
table.insert(text, string.format('%s = %q', key, value))
end
if default_code then
add_text('default', default_code)
end
if alternate_code then
add_text('unit', alternate_code)
end
if fixed_name then
add_text('name', fixed_name)
end
local subdiv = string.format('["%s"] = { %s }', ucodes[2], table.concat(text, ', '))
local main_code = ucodes[1]
local item = data[main_code]
if item then
table.insert(item.subdivs, subdiv)
else
data[main_code] = { subdivs = { subdiv } }
end
end
end
local function make_outputmultiple(data)
-- Return a function which, when called, stores a table that defines a
-- single multiple output unit. The table is stored in data (also a table).
return function (utype, fields)
-- Store a table defining a unit.
-- This is for a multiple unit like 'ydftin' (result in yards, feet, inches).
-- The target units must be defined first.
-- Throw an error if a problem occurs.
local unit = { utype = utype }
local ucodes, scales = {}, {}
for i, v in ipairs(fields) do
if i == 1 then -- unitcode
if v == '' then
error('Missing unit code for a multiple', 0)
end
unit.unitcode = v
elseif v == '' then
-- Ignore empty fields.
else
local target = get_unit(v)
if target == nil then
error('Unit "' .. v .. '" in multiple "' .. unit.unitcode .. '" not defined', 0)
end
if target.utype ~= utype then
error('Unit "' .. v .. '" in multiple "' .. unit.unitcode .. '" has wrong type', 0)
end
table.insert(ucodes, v)
table.insert(scales, target.scale)
end
end
if #ucodes < 2 then
local msg
if #ucodes == 0 then
msg = 'No units specified for multiple "' .. unit.unitcode .. '"'
else
msg = 'Only one unit specified for multiple "' .. unit.unitcode .. '"'
end
error(msg, 0)
end
-- Component units must be specified from most-significant to least-significant
-- (so scale values will be in descending order),
-- and each ratio of a pair of scales must be very close to an integer.
-- The componenets and ratios are stored in reverse order (least significant first).
-- This script stores a unit scale as a string (might be an expression like "5/9"),
-- but scales in a multiple are handled as numbers (should never be expressions).
local ratios, count = {}, #scales
for i = 1, count do
local scale = tonumber(scales[i])
if scale == nil or scale <= 0 then
error('Multiple "' .. unit.unitcode .. '" has a component with an invalid scale, "' .. scales[i] .. '"', 0)
end
scales[i] = scale
end
for i = 1, count - 1 do
local ratio = scales[i] / scales[i + 1]
local rounded = math.floor(ratio + 0.5)
if rounded < 2 then
error('Multiple "' .. unit.unitcode .. '" has components in wrong order or with invalid scales', 0)
end
if math.abs(ratio - rounded)/ratio > 1e-6 then
error('Multiple "' .. unit.unitcode .. '" has components where scale ratios are not integers', 0)
end
ratios[i] = rounded
end
unit.combination = reversed(ucodes)
unit.multiple = reversed(ratios)
insert_unique_unit(data, unit, units_index)
end
end
local out_unit_prefix = [[
---------------------------------------------------------------------------
-- Do not change the data in this table because it is created by running --
-- a script that reads the wikitext from a wiki page (see note above). --
---------------------------------------------------------------------------
local all_units = {
]]
local out_unit_suffix = [[
}
]]
local out_default_prefix = [[
---------------------------------------------------------------------------
-- Do not change the data in this table because it is created by running --
-- a script that reads the wikitext from a wiki page (see note above). --
---------------------------------------------------------------------------
local default_exceptions = {
-- Prefixed units with a default different from that of the base unit.
-- Each key item is a prefixed symbol (unitcode for engineering notation).
]]
local out_default_suffix = [[
}
]]
local out_default_item = [[
["{symbol}"] = "{default}",
]]
local out_link_prefix = [[
---------------------------------------------------------------------------
-- Do not change the data in this table because it is created by running --
-- a script that reads the wikitext from a wiki page (see note above). --
---------------------------------------------------------------------------
local link_exceptions = {
-- Prefixed units with a linked article different from that of the base unit.
-- Each key item is a prefixed symbol (not unitcode).
]]
local out_link_suffix = [[
}
]]
local out_link_item = [[
["{symbol}"] = "{link}",
]]
local combination_specification = { -- pure combination like 'm ft', or a multiple like 'ftin'
'combination',
'multiple',
'utype',
}
local alias_specification = {
'target',
'symbol',
'sp_us',
'default',
'link',
'symlink',
'customary',
'multiplier',
}
local per_specification = {
'per',
'symbol',
'sp_us',
'utype',
'invert',
'iscomplex',
'default',
'link',
'symlink',
'customary',
}
local shouldbe_specification = {
'shouldbe',
}
local unit_specification = {
'_name1',
'_name1_us',
'_symbol',
'prefix_position',
'name1',
'name1_us',
'name2',
'name2_us',
'symbol',
'sym_us',
'usename',
'usesymbol',
'utype',
'alttype',
'builtin',
'scale',
'offset',
'invert',
'iscomplex',
'istemperature',
'exception',
'prefixes',
'default',
'subdivs',
'link',
'customary',
'sp_us',
}
local no_quotes = {
combination = true,
customary = true,
multiple = true,
multiplier = true,
offset = true,
per = true,
prefix_position = true,
scale = true,
subdivs = true,
}
local function unit_lines(unit, spec)
-- Return string of lines of Lua source that defines a unit.
local first_item = ' ["' .. unit.unitcode .. '"] = {'
local last_item = ' },'
local t = { first_item }
for _, k in ipairs(spec) do
local v = unit[k]
if v then
local want_quotes = (type(v) == 'string' and not no_quotes[k])
if type(v) == 'boolean' then
v = tostring(v)
elseif type(v) == 'number' or k == 'scale' then
-- Replace results like '1e-006' with '1e-6'.
v = string.gsub(tostring(v), '(e[+-])0+([1-9].*)', '%1%2', 1)
elseif type(v) ~= 'string' then
error('Fatal error: unknown data type for ' .. unit.unitcode)
end
local fmt = string.format('\t%%s%s = %%%s,',
(#k < 8) and '\t' or '',
want_quotes and 'q' or 's')
t[#t+1] = fmt:format(k, v)
end
end
t[#t+1] = last_item
t[#t+1] = '' -- so last_item gets '\n'
return table.concat(t, '\n')
end
local function numbered_table_as_string(data, unit)
local t = {}
for _, v in ipairs(data) do
if type(v) == 'string' then
table.insert(t, '"' .. v .. '"')
elseif type(v) == 'number' then
table.insert(t, tostring(v))
else
error('Fatal error: unknown data type for ' .. unit.unitcode)
end
end
return '{ ' .. table.concat(t, ', ') .. ' }'
end
local function write_results(outfile, units, defaults, links)
io.output(outfile)
io.write(file_preamble)
io.write(out_unit_prefix)
for _, unit in ipairs(units) do
local spec
if unit.target then
spec = alias_specification
elseif unit.per then
spec = per_specification
unit.per = numbered_table_as_string(unit.per, unit)
elseif unit.shouldbe then
spec = shouldbe_specification
elseif unit.combination then
spec = combination_specification
unit.combination = numbered_table_as_string(unit.combination, unit)
if unit.multiple then
unit.multiple = numbered_table_as_string(unit.multiple, unit)
end
else
spec = unit_specification
end
io.write(unit_lines(unit, spec))
end
io.write(out_unit_suffix)
io.write(out_default_prefix)
for _, unit in ipairs(defaults) do
io.write((out_default_item:gsub('{([%w_]+)}', unit)))
end
io.write(out_default_suffix)
io.write(out_link_prefix)
for _, unit in ipairs(links) do
io.write((out_link_item:gsub('{([%w_]+)}', unit)))
end
io.write(out_link_suffix)
io.write(file_postamble)
io.close()
end
local function extract_heading(line)
-- Return n, s where n = heading level number (nil if none), and
-- s = heading text (with leading/trailing whitespace removed).
local pattern = '^(==+)%s*(.-)%s*(==+)%s*$'
local before, heading, after = line:match(pattern)
if heading and #heading > 0 then
-- Don't bother checking if before == after.
return #before, heading
end
end
local function fields(line)
-- Return a numbered table of fields split from line.
-- Items are delimited by "||".
-- Each item has leading/trailing whitespace removed, and any encoded pipe
-- characters are decoded.
-- The second field (for symbol when processing units) is adjusted to
-- remove any "colspan" at the front of lines like:
-- "| unitcode || colspan="11" | !Text to display for an error message".
local t = {}
line = line .. "||" -- to get last field
for item in line:gmatch("%s*(.-)%s*||") do
table.insert(t, (item:gsub('|', '|')))
end
local cleaned = t[2]:match('^%s*colspan%s*=.-|%s*(.*)$')
if cleaned then
t[2] = cleaned
end
return t
end
local function prepare_section(maker, lines, section, maxerrors)
-- Process the first level-two section with the given section name
-- in the given table of lines of wikitext.
-- If successful, maker inserts each item into a table.
-- Otherwise, an error is thrown.
local skip = true
local errors = {}
local utype -- unit type (from level-three heading)
local nbsp = '\160' -- nonbreaking space is utf-8 encoded as hex c2 a0
for linenumber, line in ipairs(lines) do
if skip then
-- Skip down to and including the starting heading.
local level, heading = extract_heading(line)
if level == 2 and heading == section then
skip = false
end
else
-- Accummulate unit definitions.
local c1 = line:sub(1, 1)
local c2 = line:sub(2, 2)
if c1 == '|' and not (c2 == '-' or c2 == '}') then
if empty(utype) then
error('No level 3 heading before: ' .. line, 0)
end
if line:find(nbsp, 1, true) then
-- For example, "acre ft" does not work if it contains nbsp.
print('Warning: line ' .. linenumber .. ' contains a nonbreaking space')
end
local ok, msg = pcall(maker, utype, fields(line:sub(2)))
if not ok then
table.insert(errors, msg .. ' (line ' .. linenumber .. ')')
if #errors >= maxerrors then
break
end
end
else
local level, heading = extract_heading(line)
if level == 3 then
utype = heading:lower()
elseif level == 2 then
break
end
end
end
end
if #errors > 0 then
error(table.concat(errors, '\n'), 0)
end
end
local function prepare_data(filename, maxerrors)
-- Read the file with the given name, and process the wikitext
-- in the sections with wanted level-two headings.
-- Return units, defaults, links (three tables).
-- Throw an error if a problem occurs.
if filename == nil then
error('Need name of file with unit definitions', 0)
end
print('Reading wikitext from file ' .. filename)
local composites, defaults, links, units = {}, {}, {}, {}
local sections = {
-- LATER: Section names must be in English to match following text.
{ 'Overrides' , make_override , overrides },
{ 'Conversions' , make_unit , units },
{ 'Output multiples', make_outputmultiple, units },
{ 'Combinations' , make_combination , units },
{ 'Input multiples' , make_inputmultiple , composites }, -- after all units defined so default will be defined
{ 'Defaults' , make_default , defaults },
{ 'Links' , make_link , links },
}
local lines = readlines(filename, 2)
for _, section in ipairs(sections) do
local heading = section[1]
local maker = section[2](section[3])
prepare_section(maker, lines, heading, maxerrors)
end
check_all_defaults(units, maxerrors)
check_all_pers(units, maxerrors)
update_units(units, composites)
return units, defaults, links
end
local function main(text_module, infile, outfile)
if not text_module then
print('Must specify text_module in first argument.')
print('Error, output not created.')
os.exit(1)
end
local text_code = require(text_module)
SIprefixes = text_code.SIprefixes
eng_scales = text_code.eng_scales
local translation = text_code.translation_table
if translation then
if translation.plural_suffix then
plural_suffix = translation.plural_suffix
end
local ts = translation.specials
if ts then
if ts.utype then
specials.utype = ts.utype
end
if ts.ucode then
specials.ucode = ts.ucode
end
end
end
local ok, units, defaults, links = pcall(prepare_data, infile, 20)
if ok then
write_results(outfile, units, defaults, links)
print('Results written to file ' .. outfile)
else
print('Error, output not created.')
print(units)
os.exit(1)
end
end
main(arg[1], arg[2] or 'wikitable.tmp', arg[3] or 'makeunits.tmp')