Add CowLeaf to be used by CowTree

4 files changed, 110 insertions, 0 deletions

diff --git a/obnamlib/__init__.py b/obnamlib/__init__.py
index ced359d0..9590fe7a 100644
--- a/obnamlib/__init__.py
+++ b/obnamlib/__init__.py
@@ -187,6 +187,7 @@ from .fmt_ga import (
     GAChunkStore,
     GAChunkIndexes,
     InMemoryLeafStore,
+    CowLeaf,
 )
 
 
diff --git a/obnamlib/fmt_ga/__init__.py b/obnamlib/fmt_ga/__init__.py
index a0f9039b..394d3c31 100644
--- a/obnamlib/fmt_ga/__init__.py
+++ b/obnamlib/fmt_ga/__init__.py
@@ -18,6 +18,7 @@
 from .client_list import GAClientList
 from .chunk_store import GAChunkStore
 from .leaf_store import InMemoryLeafStore
+from .leaf import CowLeaf
 from .indexes import GAChunkIndexes
 from .dirobj import GADirectory, GAImmutableError, create_gadirectory_from_dict
 from .tree import GATree
diff --git a/obnamlib/fmt_ga/leaf.py b/obnamlib/fmt_ga/leaf.py
new file mode 100644
index 00000000..6522a6a9
--- /dev/null
+++ b/obnamlib/fmt_ga/leaf.py
@@ -0,0 +1,43 @@
+# Copyright 2016  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import copy
+
+
+class CowLeaf(object):
+
+    def __init__(self):
+        self._dict = {}
+
+    def __len__(self):
+        return len(self._dict)
+
+    def keys(self):
+        return self._dict.keys()
+
+    def lookup(self, key):
+        return self._dict.get(key, None)
+
+    def insert(self, key, value):
+        self._dict[key] = value
+
+    def as_dict(self):
+        return copy.deepcopy(self._dict)
+
+    def from_dict(self, a_dict):
+        self._dict = a_dict
diff --git a/obnamlib/fmt_ga/leaf_tests.py b/obnamlib/fmt_ga/leaf_tests.py
new file mode 100644
index 00000000..6c5f2903
--- /dev/null
+++ b/obnamlib/fmt_ga/leaf_tests.py
@@ -0,0 +1,65 @@
+# Copyright 2016  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import unittest
+
+import obnamlib
+
+
+class CowLeafTests(unittest.TestCase):
+
+    def test_has_zero_length_initially(self):
+        leaf = obnamlib.CowLeaf()
+        self.assertEqual(len(leaf), 0)
+
+    def test_has_no_keys_initially(self):
+        leaf = obnamlib.CowLeaf()
+        self.assertEqual(leaf.keys(), [])
+
+    def test_lookup_returns_None_if_key_is_missing(self):
+        leaf = obnamlib.CowLeaf()
+        self.assertEqual(leaf.lookup(42), None)
+
+    def test_lookup_returns_inserted_value(self):
+        key = 'fookey'
+        value = 'barvalue'
+        leaf = obnamlib.CowLeaf()
+        leaf.insert(key, value)
+        self.assertEqual(leaf.lookup(key), value)
+
+    def test_inserting_increases_length(self):
+        leaf = obnamlib.CowLeaf()
+        leaf.insert('foo', 'bar')
+        self.assertEqual(len(leaf), 1)
+
+    def test_inserting_adds_key(self):
+        leaf = obnamlib.CowLeaf()
+        leaf.insert('foo', 'bar')
+        self.assertEqual(leaf.keys(), ['foo'])
+
+    def test_dict_round_trip(self):
+        leaf = obnamlib.CowLeaf()
+        leaf.insert('foo', 'bar')
+        some_dict = leaf.as_dict()
+
+        leaf2 = obnamlib.CowLeaf()
+        leaf2.from_dict(some_dict)
+        some_dict2 = leaf2.as_dict()
+
+        self.assertNotEqual(id(some_dict), id(some_dict2))
+        self.assertEqual(some_dict, some_dict2)