From d101acfb563b495c0a38037c683980b91fe43259 Mon Sep 17 00:00:00 2001
From: Arthur de Jong <arthur@arthurdejong.org>
Date: Mon, 20 Jun 2011 20:55:58 +0000
Subject: use the ean module for calculating the check digit

git-svn-id: http://arthurdejong.org/svn/python-stdnum/python-stdnum@71 9dea7c4f-944c-4273-ac1a-574ede026edc
---
 stdnum/isbn.py | 13 +++++--------
 stdnum/ismn.py | 15 ++++++---------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/stdnum/isbn.py b/stdnum/isbn.py
index 7c15541..05f311c 100644
--- a/stdnum/isbn.py
+++ b/stdnum/isbn.py
@@ -1,4 +1,4 @@
-# __init__.py - functions for handling ISBNs
+# isbn.py - functions for handling ISBNs
 #
 # Copyright (C) 2010, 2011 Arthur de Jong
 #
@@ -39,6 +39,8 @@ False
 '978-1-85798-218-3'
 """
 
+from stdnum import ean
+
 
 def compact(number, convert=False):
     """Convert the ISBN to the minimal representation. This strips the number
@@ -58,11 +60,6 @@ def _calc_isbn10_check_digit(number):
     check = sum( (i + 1) * int(n) for i, n in enumerate(number) ) % 11
     return 'X' if check == 10 else str(check)
 
-def _calc_isbn13_check_digit(number):
-    """Calculate the ISBN check digit for 13-digit numbers. The number passed
-    should not have the check bit included."""
-    return str((10 - sum( (2 * (i % 2) + 1) * int(n) for i, n in enumerate(number))) % 10)
-
 def isbn_type(number):
     """Check the passed number and returns 'ISBN13', 'ISBN10' or None (for
     invalid) for checking the type of number passed."""
@@ -79,7 +76,7 @@ def isbn_type(number):
     elif len(number) == 13:
         if not number.isdigit():
             return None
-        if _calc_isbn13_check_digit(number[:-1]) != number[-1]:
+        if ean.calc_check_digit(number[:-1]) != number[-1]:
             return None
         return 'ISBN13'
     else:
@@ -99,7 +96,7 @@ def to_isbn13(number):
     if len(min_number) == 13:
         return number # nothing to do, already ISBN-13
     # put new check digit in place
-    number = number[:-1] + _calc_isbn13_check_digit('978' + min_number[:-1])
+    number = number[:-1] + ean.calc_check_digit('978' + min_number[:-1])
     # add prefix
     if ' ' in number:
         return '978 ' + number
diff --git a/stdnum/ismn.py b/stdnum/ismn.py
index 4dc6afc..38dc059 100644
--- a/stdnum/ismn.py
+++ b/stdnum/ismn.py
@@ -1,6 +1,6 @@
-# __init__.py - functions for handling ISMNs
+# ismn.py - functions for handling ISMNs
 #
-# Copyright (C) 2010 Arthur de Jong
+# Copyright (C) 2010, 2011 Arthur de Jong
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -38,6 +38,8 @@ False
 '9790230671187'
 """
 
+from stdnum import ean
+
 
 def compact(number):
     """Convert the ISMN to the minimal representation. This strips the number
@@ -45,11 +47,6 @@ def compact(number):
     number = number.replace(' ','').replace('-','').replace('.','').strip().upper()
     return number
 
-def _calc_check_digit(number):
-    """Calculate the ISMN check digit. The number passed should not have
-    the check bit included and should be in the 13-digit form."""
-    return str((10 - sum( (2 * (i % 2) + 1) * int(n) for i, n in enumerate(number))) % 10)
-
 def is_valid(number):
     """Checks to see if the number provided is a valid ISMN (either a legacy
     10-digit one or a 13-digit one). This checks the length and the check
@@ -59,10 +56,10 @@ def is_valid(number):
     except:
         return False
     if len(number) == 10 and number[0] == 'M' and number[1:].isdigit():
-        if _calc_check_digit('9790' + number[1:-1]) == number[-1]:
+        if ean.calc_check_digit('9790' + number[1:-1]) == number[-1]:
             return True
     elif len(number) == 13 and number.isdigit():
-        if _calc_check_digit(number[:-1]) == number[-1]:
+        if ean.calc_check_digit(number[:-1]) == number[-1]:
             return True
     return False
 
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