Add LeafStore class for storing CowTree nodes

CowTree will be written soon.

4 files changed, 91 insertions, 1 deletions

diff --git a/obnamlib/__init__.py b/obnamlib/__init__.py
index ee5f5516..ced359d0 100644
--- a/obnamlib/__init__.py
+++ b/obnamlib/__init__.py
@@ -185,7 +185,9 @@ from .fmt_ga import (
     create_gadirectory_from_dict,
     GATree,
     GAChunkStore,
-    GAChunkIndexes)
+    GAChunkIndexes,
+    InMemoryLeafStore,
+)
 
 
 #
diff --git a/obnamlib/fmt_ga/__init__.py b/obnamlib/fmt_ga/__init__.py
index 08875782..a0f9039b 100644
--- a/obnamlib/fmt_ga/__init__.py
+++ b/obnamlib/fmt_ga/__init__.py
@@ -17,6 +17,7 @@
 
 from .client_list import GAClientList
 from .chunk_store import GAChunkStore
+from .leaf_store import InMemoryLeafStore
 from .indexes import GAChunkIndexes
 from .dirobj import GADirectory, GAImmutableError, create_gadirectory_from_dict
 from .tree import GATree
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)
diff --git a/obnamlib/fmt_ga/leaf_store_tests.py b/obnamlib/fmt_ga/leaf_store_tests.py
new file mode 100644
index 00000000..7eb3c8e4
--- /dev/null
+++ b/obnamlib/fmt_ga/leaf_store_tests.py
@@ -0,0 +1,47 @@
+# 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
+
+
+# Pylint doesn't like the LeafStoreTests class, since its methods use
+# attributes that aren't defined in the class (they're defined by the
+# subclass). However, we know they'll be defined in time and also we
+# want the test cases to be defined only once. So we silence pylint's
+# no-member warning for this file.
+#
+# pylint: disable=no-member
+
+class LeafStoreTests(object):
+
+    def test_roundtrip_works(self):
+        leaf = {'foo': 'bar'}
+        leaf_id = self.ls.put_leaf(leaf)
+        leaf2 = self.ls.get_leaf(leaf_id)
+        self.assertEqual(leaf, leaf2)
+
+    def test_returns_None_if_leaf_is_missing(self):
+        self.assertEqual(self.ls.get_leaf(42), None)
+
+
+class InMemoryLeafStoreTests(unittest.TestCase, LeafStoreTests):
+
+    def setUp(self):
+        self.ls = obnamlib.InMemoryLeafStore()