Module:Format ISBN
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Documentation for this module may be created at Module:Format ISBN/doc
require ('strict');
local data = mw.loadData ('Module:Format ISBN/data'); -- fetch separator positioning data
local hyphen_pos_t = data.hyphen_pos_t; -- the hyphen positioning data k/v table
local index_t = data.index_t; -- an index sequence into the hyphen positioning data table; used by binary_search()
local idx_count = data.count; -- from count = #index_t; in ~/data; used by binary_search()
--[[--------------------------< B I N A R Y _ S E A R C H >----------------------------------------------------
do a binary search for the hyphen positioning data for <target_isbn> in <hyphen_pos_t> using its index sequence
<index_t>.
accepts one input <target_isbn> (a string) which it converts to a number
returns index into <hyphen_pos_t> as a number when proper formatting is found; nil else
]]
local function binary_search (target_isbn)
target_isbn = tonumber (target_isbn); -- convert to number because index_t[x] values are numbers
if (index_t[1] >= target_isbn) or (index_t[idx_count] < target_isbn) then -- invalid; out of range; 9780000000000 to whatever the last value is
return; -- TODO: return something meaningful?
end
local idx_bot = 1; -- initialize to index 1 (first element in <index_t>)
local idx_top = idx_count; -- initialize to index of last element in <index_t>
while idx_bot ~= idx_top do
local idx_mid = math.ceil ((idx_bot + idx_top) / 2); -- get the mid-point in the index sequence
if index_t[idx_mid] >= target_isbn then -- when mid-point index value is greater than or equal to the target isbn
if index_t[idx_mid-1] < target_isbn then -- and when the preceding <index_t> value is less than the target isbn
return index_t[idx_mid]; -- we found the correct mapping for <target> isbn; return index into <hyphen_pos_t>
end
idx_top = idx_mid - 1; -- adjust <idx_top>
else
idx_bot = idx_mid; -- adjust <idx_bot>
end
end
mw.logObject ('didn\'t find formatting for isbn: ' .. target_isbn); -- just in case for the nonce
end
--[[--------------------------< C O N V E R T _ T O _ I S B N 1 0 >--------------------------------------------
convert 13-digit isbn to 10-digit isbn; removes 978 GS1 prefix and recalculates the check digit
takes a single input; the 13-digit isbn as a string without separators
assumes that the GS1 prefix is 978; there is no mapping between isbn10 and 979-prefixed isbn13. calling functions
are required to ensure that <isbn13> is a properly formed string of 13 digits (no separators) that begins with 978.
]]
local function convert_to_isbn10 (isbn13)
local isbn9 = isbn13:sub (4, 12); -- get the 9 digits of <isbn13> that follow the '978' GS1 prefix (drop the check digit)
local check = 0; -- initialize the check digit calculation
local i = 1; -- index
for j=10, 2, -1 do -- <j> is weighting for each of the 9 digits; counting down, left to right
check = check + tonumber (isbn9:sub (i, i)) * j; -- accumulate the sum the weighted-digit-products
i = i + 1; -- bump the index
end
check = check % 11; -- remainder of the weighted-digit-products divided by 11
if 0 == check then
return isbn9 .. '0'; -- special case
else
check = 11 - check; -- calculate the check digit
return isbn9 .. ((10 == check) and 'X' or check); -- when <check> is ten, use 'X'; <check> else
end
end
--[[--------------------------< C O N V E R T _ T O _ I S B N 1 3 >--------------------------------------------
convert 10-digit isbn to 13-digit isbn; adds 978 GS1 prefix and recalculates the check digit
takes a single input; the 10-digit isbn as a string (no separators)
]]
local function convert_to_isbn13 (isbn10)
local isbn12 = '978'.. isbn10:sub(1, 9); -- concatenate '978' with first 9 digits of <isbn10> (drop the check digit)
local check = 0; -- initialize the check digit calculation
for i=1, 12 do -- for the first 12 digits ('978' and 9 others)
check = check + tonumber (isbn12:sub (i, i)) * (3 - (i % 2) * 2); -- accumulate checksum
end
return isbn12 .. ((10 - (check % 10)) %10); -- extract check digit from checksum; append and done
end
--[[--------------------------< _ F O R M A T _ I S B N >------------------------------------------------------
Module entry point when require()'d into another module
takes five inputs:
<isbn_str> – isbn as a string
<show_err_msg>: boolean: when true, shows error message returned from check_isbn(); no message else
<separator>: boolean: when true, use space character as separator; hyphen else
<template_name>: supplied by the template for use in error messaging
<output_format>: a value of 10 or 13 dictates the format of the output; other values ignored
returns formatted sbn, isbn10, or isbn13 (whichever was the input or per |out=) on success; initial <isbn_str> else
]]
local function _format_isbn (isbn_str, show_err_msg, separator, output_format, template_name)
if (not isbn_str) or ('' == isbn_str) then
return ''; -- empty or nil input? empty output
end
local isbn_str_raw = isbn_str; -- this will be the return value if unable to format
isbn_str = isbn_str:gsub ('[^%dX]', ''); -- strip all formatting (spaces and hyphens) from the isbn/sbn
local flags = {}; -- a convenient place for flag stuff
if '13' == output_format then -- set a flag for output format; ignored when <isbn_str> is an sbn
flags.out13 = true;
elseif '10' == output_format then
flags.out10 = true;
end
if 9 == #isbn_str then -- looks like an sbn?
isbn_str = '0' .. isbn_str; -- convert to isbn10
flags.sbn = true; -- set a flag
end
local err_msg = require ("Module:Check isxn").check_isbn ({args={isbn_str, template_name=template_name}}); -- does <isbn_str> 'look' like a valid isbn? does not check ranging
if '' ~= err_msg then -- when there is an error message
if show_err_msg then -- and we are showing error messages
return isbn_str_raw, err_msg; -- return our input and the message
else
return isbn_str_raw; -- not showing error messages; return our input without the message
end
end
if 13 == #isbn_str and flags.out10 then -- if isbn13 but we want an isbn10 output
flags.isbn10_check_digit = (convert_to_isbn10 (isbn_str)):sub (-1); -- calculate and extract the isbn10 check digit for later
end
if 10 == #isbn_str then -- if isbn10 or sbn
flags.isbn10_check_digit = isbn_str:sub (-1); -- extract the check digit for later
isbn_str = convert_to_isbn13 (isbn_str); -- convert isbn10 to isbn13 for formatting
end
local index = binary_search (isbn_str); -- look for the formatting that applies to <isbn_str>
if index then -- if found
local format_t = hyphen_pos_t[index]; -- get the formatting sequence
local result_t = {isbn_str:sub (1, 3)}; -- init <result_t> with prefix; the GS1 prefix element ('978' or '979')
local digit_ptr = 4; -- initialize to point at registration group element
for _, n in ipairs (format_t) do -- loop through the formatting sequence to build a sequence of isbn13 elements
table.insert (result_t, isbn_str:sub (digit_ptr, digit_ptr+n-1)); -- add the digits from <isbn_str>[<digit_ptr>] to <isbn_str>[<digit_ptr+n-1>] to <result_t> sequence
digit_ptr = digit_ptr + n; -- advance the digit pointer
end
table.insert (result_t, isbn_str:sub (13)); -- and add the check digit element to <result_t>
isbn_str = table.concat (result_t, separator and ' ' or '-'); -- assemble formatted <isbn_str> with space or hyphen (default) separators
if flags.isbn10_check_digit then -- if we saved the check digit from an sbn or isbn10
if flags.sbn then -- when input is an sbn
isbn_str = isbn_str:gsub ('^978%-0%-', ''):gsub ('%d$', flags.isbn10_check_digit); -- remove GS1 prefix element and registration group element; restore check digit
else -- when input is an isbn10
if not flags.out13 then
isbn_str = isbn_str:gsub ('^978%-', ''):gsub ('%d$', flags.isbn10_check_digit); -- remove GS1 prefix element; restore check digit
end
end
end
return isbn_str; -- return formatted <isbn_str>
end
return isbn_str_raw; -- should never actually be reached; but, if we do, return original input string
end
--[[--------------------------< F O R M A T _ P L A I N >------------------------------------------------------
plain text output:
no linking to Special:BookSources
no error message output – on error, return input; for use in cs1|2 template |isbn= params, no point in causing confusion due to multiple error messages
|separator=space – render formatted ISBN with spaces instead of hyphens
|out= – takes either of 10 or 13 to specify the output format if different from the default
{{#invoke:format isbn|format_plain}}
]]
local function format_plain (frame)
local args_t = require ('Module:Arguments').getArgs (frame); -- get template and invoke parameters
local isbn_str = args_t[1];
local separator = 'space' == args_t.separator; -- boolean: when true use space separator; hyphen else
local output_format = args_t.out; -- 10 or 13 to convert input format to the other for output
return _format_isbn (isbn_str, nil, separator, output_format); -- no error messaging
end
--[[--------------------------< F O R M A T _ L I N K >--------------------------------------------------------
linked text output:
links to Special:BookSources
|suppress-errors=yes – suppress error messages
|separator=space – render formatted ISBN with spaces instead of hyphens
|out= – takes either of 10 or 13 to specify the output format if different from the default
{{#invoke:format isbn|format_linked|template=Format ISBN link}}
]]
local function format_linked (frame)
local args_t = require ('Module:Arguments').getArgs (frame); -- get template and invoke parameters
local isbn_str = args_t[1];
local show_err_msg = 'yes' ~= args_t['suppress-errors']; -- always show errors unless |suppress-errors=yes
local separator = 'space' == args_t.separator; -- boolean: when true use space separator; hyphen else
local output_format = args_t.out; -- 10 or 13 to convert input format to the other for output
local formatted_isbn_str, err_msg = _format_isbn (isbn_str, show_err_msg, separator, output_format, args_t.template_name); -- show error messages unless suppressed
if err_msg then
return formatted_isbn_str .. ' ' .. err_msg; -- return unformatted, unlinked isbn and error message
else
return '[[Special:BookSources/' ..isbn_str .. '|' .. formatted_isbn_str ..']]'; -- return formatted and linked isbn
end
end
--[[--------------------------< E X P O R T S >----------------------------------------------------------------
]]
return {
format_plain = format_plain, -- template entry points
format_linked = format_linked,
_format_isbn = _format_isbn, -- entry point when this module require()'d into another module
}