diff options
Diffstat (limited to 'script/3rd/lua-uri/uri/urn/issn.lua')
-rw-r--r-- | script/3rd/lua-uri/uri/urn/issn.lua | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/script/3rd/lua-uri/uri/urn/issn.lua b/script/3rd/lua-uri/uri/urn/issn.lua new file mode 100644 index 00000000..c5f37f8c --- /dev/null +++ b/script/3rd/lua-uri/uri/urn/issn.lua @@ -0,0 +1,65 @@ +local M = { _NAME = "uri.urn.issn" } +local Util = require "uri._util" +local URN = require "uri.urn" +Util.subclass_of(M, URN) + +local function _parse_issn (issn) + local _, _, nums1, nums2, checksum + = issn:find("^(%d%d%d%d)-?(%d%d%d)([%dxX])$") + if checksum == "x" then checksum = "X" end + return nums1, nums2, checksum +end + +local function _valid_issn (issn) + local nums1, nums2, actual_checksum = _parse_issn(issn) + if not nums1 then return nil, "invalid ISSN syntax" end + local nums = nums1 .. nums2 + + local expected_checksum = 0 + for i = 1, 7 do + expected_checksum = expected_checksum + tonumber(nums:sub(i, i)) * (9 - i) + end + expected_checksum = (11 - expected_checksum % 11) % 11 + expected_checksum = (expected_checksum == 10) and "X" + or tostring(expected_checksum) + if actual_checksum ~= expected_checksum then + return nil, "wrong checksum, expected " .. expected_checksum + end + + return true +end + +local function _normalize_issn (issn) + local nums1, nums2, checksum = _parse_issn(issn) + return nums1 .. "-" .. nums2 .. checksum +end + +function M.init (self) + local nss = self:nss() + local ok, msg = _valid_issn(nss) + if not ok then return nil, "bad NSS value for ISSN URI (" .. msg .. ")" end + M._SUPER.nss(self, _normalize_issn(nss)) + return self +end + +function M.nss (self, new) + local old = M._SUPER.nss(self) + + if new then + local ok, msg = _valid_issn(new) + if not ok then + error("bad ISSN value '" .. new .. "' (" .. msg .. ")") + end + M._SUPER.nss(self, _normalize_issn(new)) + end + + return old +end + +function M.issn_digits (self, new) + local old = self:nss(new) + return old:sub(1, 4) .. old:sub(6, 9) +end + +return M +-- vi:ts=4 sw=4 expandtab |