From 518ee5b97043d69d50d0429984fb8fdaf5058640 Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Sun, 30 Jan 2022 15:03:59 +0100
Subject: [PATCH] ravl: add ravl tree

Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 ravl.py      |  34 +++++++++++++
 test_ravl.py | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 167 insertions(+)
 create mode 100644 ravl.py
 create mode 100644 test_ravl.py

diff --git a/ravl.py b/ravl.py
new file mode 100644
index 0000000..7b15f98
--- /dev/null
+++ b/ravl.py
@@ -0,0 +1,34 @@
+from wavl import WAVLTree
+from node import Node, Comparable
+
+import logging
+from typing import TypeVar, Optional
+
+logger = logging.getLogger(__name__)
+T = TypeVar("T", bound=Comparable)
+
+
+class RAVLTree(WAVLTree[T]):
+    def is_correct_node(
+        self, node: Optional[Node[T]], recursive: bool = True
+    ) -> bool:
+        if not node:
+            return True
+
+        if not all(child_rank > 0 for child_rank in Node.differences(node)):
+            return False
+
+        return not recursive or (
+            self.is_correct_node(node.left)
+            and self.is_correct_node(node.right)
+        )
+
+    # region DeleteRebalance
+
+    def _delete_rebalance(
+        self, node: Optional[Node[T]], parent: Optional[Node[T]]
+    ) -> None:
+        # There is no rebalance after delete in rAVL tree
+        pass
+
+    # endregion DeleteRebalance
diff --git a/test_ravl.py b/test_ravl.py
new file mode 100644
index 0000000..e61f9f6
--- /dev/null
+++ b/test_ravl.py
@@ -0,0 +1,133 @@
+from ravl import RAVLTree
+
+import hypothesis
+import hypothesis.strategies as st
+import logging
+import pytest
+import random
+
+logger = logging.getLogger(__name__)
+
+
+def test_empty():
+    tree = RAVLTree()
+
+    assert tree.root is None
+    assert tree.is_correct
+
+
+def test_one_node():
+    tree = RAVLTree()
+    tree.insert(1)
+
+    assert tree.root is not None
+    assert 1 == tree.root.value
+    assert 0 == tree.root.rank
+    assert tree.root.left is None
+    assert tree.root.right is None
+
+    assert tree.is_correct
+
+
+@pytest.mark.parametrize("values", [[1, 2], [1, 2, 0]])
+def test_no_rebalance_needed(values):
+    tree = RAVLTree()
+
+    for value in values:
+        tree.insert(value)
+        assert tree.is_correct
+
+
+def test_three_nodes_rebalanced():
+    tree = RAVLTree()
+
+    for value in (1, 2, 3):
+        print(tree)
+        tree.insert(value)
+
+    assert tree.is_correct
+
+
+def test_bigger_tree():
+    tree = RAVLTree()
+
+    for i in range(50):
+        tree.insert(i)
+        assert tree.is_correct
+
+
+def test_bigger_tree_reversed():
+    tree = RAVLTree()
+
+    for i in range(50):
+        tree.insert(-i)
+        assert tree.is_correct
+
+
+def test_promote():
+    tree = RAVLTree()
+
+    for value in (0, 1, -1):
+        tree.insert(value)
+        assert tree.is_correct
+
+
+@pytest.mark.parametrize(
+    "values",
+    [
+        [0, 1, -2, -1, -3],
+        [0, 1, -2, -1, -3, -4, 4, 9, 7],
+        [0, 1, -2, -1, -3, -4, 4, 9, 7, 5, -5, 8],
+    ],
+)
+def test_rotate(values):
+    tree = RAVLTree()
+
+    for value in values:
+        tree.insert(value)
+        assert tree.is_correct
+
+
+@hypothesis.settings(max_examples=1000, deadline=None)
+@hypothesis.given(values=st.sets(st.integers()))
+def test_insert_random(values):
+    tree = RAVLTree()
+
+    for value in values:
+        tree.insert(value)
+        assert tree.is_correct
+        assert tree.search(value) is not None
+
+
+@st.composite
+def delete_strategy(draw):
+    values = list(draw(st.sets(st.integers())))
+    delete_order = values.copy()
+    random.shuffle(delete_order)
+    return (values, delete_order)
+
+
+@hypothesis.settings(max_examples=10000, deadline=None)
+@hypothesis.given(config=delete_strategy())
+def test_delete_random(config):
+    values, delete_order = config
+
+    tree = RAVLTree()
+
+    for value in values:
+        tree.insert(value)
+
+    for value in delete_order:
+        before = str(tree)
+        tree.delete(value)
+        after = str(tree)
+
+        try:
+            assert tree.is_correct
+        except AssertionError:
+            logger.info(
+                f"[FAIL] Delete {value} from {values} in order {delete_order}"
+            )
+            logger.info(f"Before:\n{before}")
+            logger.info(f"After:\n{after}")
+            raise