Merge pull request #34 from trailofbits/21-nonetype

Adds support for null and None types

Author: ESultanik

docs/_templates/layout.html

@@ -17,6 +17,7 @@
             {% endfor %}
           {% else %}
             <dd><a href="/graphtage/latest">latest</a></dd>
+            <dd><a href="/graphtage/v0.2.1">0.2.2</a></dd>
             <dd><a href="/graphtage/v0.2.1">0.2.1</a></dd>
             <dd><a href="/graphtage/v0.2.0">0.2.0</a></dd>
             <dd><a href="/graphtage/v0.1.1">0.1.1</a></dd>

graphtage/graphtage.py

@@ -832,6 +832,37 @@ def __init__(self, bool_like: bool):
         super().__init__(bool_like)
 
 
+class NullNode(LeafNode):
+    """A node representing a null or :const:`None` type."""
+
+    def __init__(self):
+        super().__init__(None)
+
+    def calculate_total_size(self) -> int:
+        return 0
+
+    def edits(self, node: TreeNode) -> Edit:
+        if isinstance(node, NullNode):
+            return Match(self, node, 0)
+        else:
+            return Replace(self, node)
+
+    def __lt__(self, other):
+        if isinstance(other, NullNode):
+            return False
+        else:
+            return True
+
+    def __eq__(self, other):
+        return isinstance(other, NullNode)
+
+    def __hash__(self):
+        return hash(self.object)
+
+    def __repr__(self):
+        return f"{self.__class__.__name__}()"
+
+
 def string_edit_distance(s1: str, s2: str) -> EditDistance:
     """A convenience function for computing the edit distance between two strings.
 

graphtage/json.py

@@ -11,7 +11,7 @@
 from typing import Optional, Union
 
 from .graphtage import BoolNode, BuildOptions, DictNode, Filetype, FixedKeyDictNode, \
-    FloatNode, IntegerNode, KeyValuePairNode, LeafNode, ListNode, StringFormatter, StringNode
+    FloatNode, IntegerNode, KeyValuePairNode, LeafNode, ListNode, NullNode, StringFormatter, StringNode
 from .printer import Fore, Printer
 from .sequences import SequenceFormatter
 from .tree import ContainerNode, GraphtageFormatter, TreeNode
@@ -66,6 +66,8 @@ def build_tree(
             return DictNode.from_dict(dict_items)
         else:
             return FixedKeyDictNode.from_dict(dict_items)
+    elif python_obj is None:
+        return NullNode()
     else:
         raise ValueError(f"Unsupported Python object {python_obj!r} of type {type(python_obj)}")
 

graphtage/version.py

@@ -48,7 +48,7 @@ def git_branch() -> Optional[str]:
         return None
 
 
-DEV_BUILD = True
+DEV_BUILD = False
 """Sets whether this build is a development build.
 
 This should only be set to :const:`False` to coincide with a release. It should *always* be :const:`False` before
@@ -59,7 +59,7 @@ def git_branch() -> Optional[str]:
 """
 
 
-__version__: Tuple[Union[int, str], ...] = (0, 3, 0)
+__version__: Tuple[Union[int, str], ...] = (0, 2, 2)
 
 if DEV_BUILD:
     branch_name = git_branch()

test/test_graphtage.py

@@ -103,3 +103,10 @@ def test_empty_list(self):
         self.assertEqual(1, len(diff.edit_list))
         self.assertIsInstance(diff.edit_list[0], graphtage.Match)
         self.assertEqual(0, diff.edit_list[0].bounds().upper_bound)
+
+    def test_null_json(self):
+        diff = graphtage.json.build_tree([None]).diff(graphtage.json.build_tree([1]))
+        self.assertIsInstance(diff, graphtage.ListNode)
+        self.assertIsInstance(diff, graphtage.tree.EditedTreeNode)
+        self.assertEqual(1, len(diff.edit_list))
+        self.assertIsInstance(diff.edit_list[0], graphtage.FixedLengthSequenceEdit)