From 919c7c1c5a2f3bd67bbb41145433c77f52a84a7e Mon Sep 17 00:00:00 2001
From: Fabien Benureau <fabien.benureau+git@gmail.com>
Date: Fri, 28 Jun 2013 14:58:27 +0200
Subject: [PATCH] method parse for algebric tags

---
 papers/commands/tag_cmd.py | 21 +++++++++++++++++++++
 tests/test_tag.py          | 15 +++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 tests/test_tag.py

diff --git a/papers/commands/tag_cmd.py b/papers/commands/tag_cmd.py
index 398d8a2..0304d84 100644
--- a/papers/commands/tag_cmd.py
+++ b/papers/commands/tag_cmd.py
@@ -30,6 +30,27 @@ def parser(subparsers, config):
     #      indistinguisable for argparse. (fabien, 201306)
     return parser
 
+
+import re
+def _parse_tags(s):
+    tags = []
+    if s[0] not in ['+', '-']:
+        s = '+' + s
+    last = 0
+    for m in re.finditer(r'[+-]', s):
+        if m.start() == last:
+            if last != 0:
+                raise ValueError, 'could not match tag expression'
+        else:
+            tags.append(s[last:(m.start())])
+        last = m.start()
+    if last == len(s):
+        raise ValueError, 'could not match tag expression'
+    else:
+        tags.append(s[last:])
+    return tags
+
+
 def command(config, ui, referenceOrTag, tags):
     """Add, remove and show tags"""
     rp = Repository.from_directory(config)
diff --git a/tests/test_tag.py b/tests/test_tag.py
new file mode 100644
index 0000000..4dc28d6
--- /dev/null
+++ b/tests/test_tag.py
@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+import unittest
+
+import testenv
+from papers.commands.tag_cmd import _parse_tags
+
+class TestCreateCitekey(unittest.TestCase):
+
+    def test_tag_parsing(self):
+
+        self.assertEqual(['+abc', '+def9'], _parse_tags( 'abc+def9'))
+        self.assertEqual(['+abc', '-def9'], _parse_tags( 'abc-def9'))
+        self.assertEqual(['-abc', '-def9'], _parse_tags('-abc-def9'))
+        self.assertEqual(['+abc', '-def9'], _parse_tags('+abc-def9'))
+