Module:Format ISBN

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  in  using its index sequence .

accepts one input  (a string) which it converts to a number

returns index into  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 ) local idx_top = idx_count;													-- initialize to index of last element in  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  value is less than the target isbn return index_t[idx_mid];										-- we found the correct mapping for isbn; return index into  end idx_top = idx_mid - 1;												-- adjust  else idx_bot = idx_mid;													-- adjust  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 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 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															--  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 is ten, use 'X'; 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 (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 as a string : boolean: when true, shows error message returned from check_isbn; no message else : boolean: when true, use space character as separator; hyphen else : supplied by the template for use in error messaging : 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

]]

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

]]

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  .. 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 }