libgit2 · jdavid · May 28, 2014 · May 27, 2014 · May 27, 2014 · May 27, 2014
diff --git a/docs/working-copy.rst b/docs/working-copy.rst
@@ -26,6 +26,14 @@ Custom entries::
    >>> entry = pygit2.IndexEntry('README.md', blob_id, blob_filemode)
    >>> repo.index.add(entry)
 
+The index fulfills a dual role as the in-memory representation of the
+index file and data structure which represents a flat list of a
+tree. You can use it independently of the index file, e.g.
+
+  >>> index = pygit2.Index()
+  >>> entry = pygit2.IndexEntry('README.md', blob_id, blob_filemode)
+  >>> index.add(entry)
+
 The Index type
 ====================
 

diff --git a/src/index.c b/src/index.c
@@ -45,17 +45,18 @@ extern PyTypeObject RepositoryType;
 int
 Index_init(Index *self, PyObject *args, PyObject *kwds)
 {
-    char *path;
+    char *path = NULL;
     int err;
 
     if (kwds && PyDict_Size(kwds) > 0) {
         PyErr_SetString(PyExc_TypeError, "Index takes no keyword arguments");
         return -1;
     }
 
-    if (!PyArg_ParseTuple(args, "s", &path))
+    if (!PyArg_ParseTuple(args, "|s", &path))
         return -1;
 
+    self->repo = NULL;
     err = git_index_open(&self->index, path);
     if (err < 0) {
         Error_set_str(err, path);
@@ -425,26 +426,46 @@ Index_remove(Index *self, PyObject *args)
 PyDoc_STRVAR(Index_read_tree__doc__,
   "read_tree(tree)\n"
   "\n"
-  "Update the index file from the tree identified by the given oid.");
+  "Update the index file from the specified tree. The tree can be a Tree object or an Oid.\n"
+  "Using an Oid is only possible if this index is associated with a repository");
 
 PyObject *
 Index_read_tree(Index *self, PyObject *value)
 {
     git_oid oid;
-    git_tree *tree;
-    int err;
+    git_tree *tree = NULL;
+    int err, need_free = 0;
     size_t len;
 
     len = py_oid_to_git_oid(value, &oid);
-    if (len == 0)
-        return NULL;
+    if (len == 0) {
+        Tree *py_tree;
+        if (!PyObject_TypeCheck(value, &TreeType)) {
+            return NULL;
+        }
 
-    err = git_tree_lookup_prefix(&tree, self->repo->repo, &oid, len);
-    if (err < 0)
-        return Error_set(err);
+        PyErr_Clear();
+        py_tree = (Tree *) value;
+        tree = py_tree->tree;
+    }
+
+    /*
+     * if the user passed in an id but we're not associated with a
+     * repo, we can't do anything
+     */
+    if (tree == NULL && self->repo == NULL) {
+        PyErr_SetString(PyExc_TypeError, "id given but no associated repository");
+        return NULL;
+    } else if (tree == NULL) {
+        need_free = 1;
+        err = git_tree_lookup_prefix(&tree, self->repo->repo, &oid, len);
+        if (err < 0)
+            return Error_set(err);
+    }
 
     err = git_index_read_tree(self->index, tree);
-    git_tree_free(tree);
+    if (need_free)
+        git_tree_free(tree);
     if (err < 0)
         return Error_set(err);
 

diff --git a/test/test_index.py b/test/test_index.py
@@ -34,7 +34,7 @@
 import tempfile
 
 import pygit2
-from pygit2 import Repository
+from pygit2 import Repository, Index
 from . import utils
 
 
@@ -206,5 +206,19 @@ def test_create_entry(self):
         tree_id = index.write_tree()
         self.assertEqual('60e769e57ae1d6a2ab75d8d253139e6260e1f912', str(tree_id))
 
+class StandaloneIndexTest(utils.RepoTestCase):
+
+    def test_create_empty(self):
+        index = Index()
+
+    def test_create_empty_read_tree_as_string(self):
+        index = Index()
+        # no repo associated, so we don't know where to read from
+        self.assertRaises(TypeError, index, 'read_tree', 'fd937514cb799514d4b81bb24c5fcfeb6472b245')
+
+    def test_create_empty_read_tree(self):
+        index = Index()
+        index.read_tree(self.repo['fd937514cb799514d4b81bb24c5fcfeb6472b245'])
+
 if __name__ == '__main__':
     unittest.main()