Add 'hash' API method.

acidfs/__init__.py

@@ -257,6 +257,17 @@ def open(self, path, mode='r', buffering=-1, encoding=None, errors=None,
 
         raise ValueError("Bad mode: %s" % mode)
 
+    def hash(self, path=''):
+        """
+        Returns the sha1 hash of the object referred to by `path`.  If `path` is
+        omitted the current working directory is used.
+        """
+        session = self._session()
+        obj = session.find(self._mkpath(path))
+        if not obj:
+            raise _NoSuchFileOrDirectory(path)
+        return obj.hash()
+
     def listdir(self, path=''):
         """
         Return list of files in indicated directory.  If `path` is omitted, the
@@ -831,10 +842,12 @@ class _TreeNode(object):
     parent = None
     name = None
     dirty = False
+    oid = None
 
     @classmethod
     def read(cls, db, oid):
         node = cls(db)
+        node.oid = oid
         contents = node.contents
         with _popen(['git', 'ls-tree', oid],
                    stdout=subprocess.PIPE, cwd=db) as lstree:
@@ -902,6 +915,7 @@ def set(self, name, entry):
     def set_dirty(self):
         node = self
         while node and not node.dirty:
+            node.oid = None
             node.dirty = True
             node = node.parent
 
@@ -930,6 +944,7 @@ def save(self):
                 proc.stdin.write(b'\n')
             proc.stdin.close()
             oid = proc.stdout.read().strip()
+        self.oid = _s(oid)
         return oid
 
     def empty(self):
@@ -938,6 +953,11 @@ def empty(self):
     def __contains__(self, name):
         return name in self.contents
 
+    def hash(self):
+        if not self.oid:
+            self.save()
+        return self.oid
+
 
 class _Blob(object):
 
@@ -952,6 +972,9 @@ def find(self, path):
         if not path:
             return self
 
+    def hash(self):
+        return self.oid
+
 
 class _NewBlob(io.RawIOBase):
 
@@ -978,7 +1001,7 @@ def close(self):
             if retcode != 0:
                 raise subprocess.CalledProcessError(
                     retcode, 'git hash-object -w --stdin')
-            self.parent.contents[self.name] = (b'blob', oid, None)
+            self.parent.contents[self.name] = (b'blob', _s(oid), None)
 
     def writable(self):
         return True
@@ -988,6 +1011,11 @@ def open(self):
             return self.prev.open()
         raise _NoSuchFileOrDirectory(_object_path(self))
 
+    def hash(self):
+        if self.prev:
+            return self.prev.hash()
+        raise _NoSuchFileOrDirectory(_object_path(self))
+
     def find(self, path):
         if not path:
             return self

acidfs/tests.py

@@ -100,12 +100,20 @@ def assertDirectoryNotEmpty(self, path):
 
     def test_read_write_file(self):
         fs = self.make_one()
+        self.assertEqual(fs.hash(),
+                         '4b825dc642cb6eb9a060e54bf8d69288fbee4904')
+        with self.assertNoSuchFileOrDirectory('foo'):
+            fs.hash('foo')
         with fs.open('foo', 'wb') as f:
             self.assertTrue(f.writable())
             fprint(f, b'Hello')
             with self.assertNoSuchFileOrDirectory('foo'):
                 fs.open('foo', 'rb')
+            with self.assertNoSuchFileOrDirectory('foo'):
+                fs.hash('foo')
         self.assertEqual(fs.open('foo', 'rb').read(), b'Hello\n')
+        self.assertEqual(fs.hash('foo'),
+                         'e965047ad7c57865823c7d992b1d046ea66edf78')
         actual_file = os.path.join(self.tmp, 'foo')
         self.assertFalse(os.path.exists(actual_file))
         transaction.commit()
@@ -139,10 +147,14 @@ def test_read_write_file_in_subfolder(self):
         self.assertFalse(fs.isdir('foo'))
         fs.mkdir('foo')
         self.assertTrue(fs.isdir('foo'))
+        self.assertEqual(fs.hash('foo'),
+                         '4b825dc642cb6eb9a060e54bf8d69288fbee4904')
         with fs.open('foo/bar', 'wb') as f:
             fprint(f, b'Hello')
         with fs.open('foo/bar', 'rb') as f:
             self.assertEqual(f.read(), b'Hello\n')
+        self.assertEqual(fs.hash('foo'),
+                         'c57c02051dae8e2e4803530c217ac38121f393d3')
         actual_file = os.path.join(self.tmp, 'foo', 'bar')
         self.assertFalse(os.path.exists(actual_file))
         transaction.commit()
@@ -268,7 +280,11 @@ def test_modify_file(self):
         with fs.open('foo', 'wb') as f:
             fprint(f, b"Hello!")
             self.assertEqual(fs.open('foo', 'rb').read(), b'Howdy!\n')
+            self.assertEqual(fs.hash('foo'),
+                             'c564dac563c1974addaa0ac0ae028fc92b2370f1')
         self.assertEqual(fs.open('foo', 'rb').read(), b'Hello!\n')
+        self.assertEqual(fs.hash('foo'),
+                         '10ddd6d257e01349d514541981aeecea6b2e741d')
         self.assertEqual(open(path, 'rb').read(), b'Howdy!\n')
         transaction.commit()
 

docs/index.rst

@@ -168,6 +168,7 @@ API
      .. automethod:: empty
      .. automethod:: get_base
      .. automethod:: set_base
+     .. automethod:: hash
 
 .. toctree::
    :maxdepth: 2