Add LeafStore class for storing CowTree nodes

CowTree will be written soon.

1 files changed, 40 insertions, 0 deletions

diff --git a/obnamlib/fmt_ga/leaf_store.py b/obnamlib/fmt_ga/leaf_store.py
new file mode 100644
index 00000000..5a3a8627
--- /dev/null
+++ b/obnamlib/fmt_ga/leaf_store.py
@@ -0,0 +1,40 @@
+# 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+ =*=
+
+
+class LeafStoreInterface(object):  # pragma: no cover
+
+    def put_leaf(self, leaf):
+        raise NotImplementedError()
+
+    def get_leaf(self, leaf_id):
+        raise NotImplementedError()
+
+
+class InMemoryLeafStore(LeafStoreInterface):
+
+    def __init__(self):
+        self._leaves = {}
+        self._counter = 0
+
+    def put_leaf(self, leaf):
+        self._counter += 1
+        self._leaves[self._counter] = leaf
+        return self._counter
+
+    def get_leaf(self, leaf_id):
+        return self._leaves.get(leaf_id, None)