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