feat(rb): add mockup
Signed-off-by: Matej Focko <mfocko@redhat.com>
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192
rbt.py
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192
rbt.py
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@ -0,0 +1,192 @@
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from node import Node, Comparable, RotateFunction
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from ranked_tree import RankedTree
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import enum
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import logging
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from typing import Callable, Tuple, TypeVar, Optional
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logger = logging.getLogger(__name__)
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T = TypeVar("T", bound=Comparable)
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class Colour(enum.IntEnum):
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Red = 0
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Black = 1
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def colour(x: Optional[Node[T]]) -> Colour:
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if not x or not x.parent:
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return Colour.Black
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diff = Node.difference(x)
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assert diff in (0, 1)
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return Colour(diff)
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class RBTree(RankedTree[T]):
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def is_correct_node(
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self, node: Optional[Node[T]], recursive: bool = True
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) -> bool:
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if not node:
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return True
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left, right = Node.differences(node)
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if left not in (Colour.Red, Colour.Black):
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# left subtree has invalid difference
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return False
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elif right not in (Colour.Red, Colour.Black):
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# right subtree has invalid difference
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return False
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if Node.difference(node) == Colour.Red and (
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left == Colour.Red or right == Colour.Red
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):
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# two consecutive red nodes
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return False
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return not recursive or (
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self.is_correct_node(node.left)
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and self.is_correct_node(node.right)
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)
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# region InsertRebalance
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def _insert_rebalance_step(
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self,
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x: Node[T],
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d: Optional[Node[T]],
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y: Node[T],
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rotate_left: RotateFunction,
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rotate_right: RotateFunction,
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) -> Node[T]:
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p = x.parent
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pp = p.parent
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if d is not None and colour(d) == Colour.Red:
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pp.rank += 1
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x = pp
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elif x == y:
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x = p
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rotate_left(tree=self, x=p)
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else:
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rotate_right(tree=self, x=pp)
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return x
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def _insert_rebalance(self, x: Node[T]) -> None:
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while x.parent is not None and colour(x.parent) == Colour.Red:
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p = x.parent
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pp = x.parent.parent
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assert pp
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if p == pp.left:
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x = self._insert_rebalance_step(
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x, pp.right, p.right, Node.rotate_left, Node.rotate_right
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)
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else:
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x = self._insert_rebalance_step(
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x, pp.left, p.left, Node.rotate_right, Node.rotate_left
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)
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# endregion InsertRebalance
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# region DeleteRebalance
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def _delete_rebalance_step(
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self,
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x: Node[T],
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w: Node[T],
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parent: Node[T],
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left: Callable[[Node[T]], Node[T]],
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right: Callable[[Node[T]], Node[T]],
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rotate_left: RotateFunction,
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rotate_right: RotateFunction,
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) -> Tuple[Optional[Node[T]], Optional[Node[T]]]:
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if colour(w) == Colour.Red:
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logger.debug("RB-Delete: Case 1 -- x's sibling w is red")
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# w.colour = Colour.Black
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# x.parent.colour = Colour.Red
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rotate_left(tree=self, x=parent)
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w = right(parent)
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if colour(w.left) == Colour.Black and colour(w.right) == Colour.Black:
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logger.debug(
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"RB-Delete: Case 2 -- x's sibling w is black, and both of w's children are black"
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)
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# w.colour = Colour.Red
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parent.rank -= 1
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x = parent
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else:
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if colour(right(w)) == Colour.Black:
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logger.debug(
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"RB-Delete: Case 3 -- x's sibling w is black, w's left child is red, and w's right child is black"
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)
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# left(w).colour = Colour.Black
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# w.colour = Colour.Red
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rotate_right(tree=self, x=w)
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w = right(parent)
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logger.debug(
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"RB-Delete: Case 4 -- x's sibling w is black, and w's right child is red"
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)
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# w.colour = colour(x.parent)
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# x.parent.colour = Colour.Black
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# right(w).colour = Colour.Black
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rotate_left(tree=self, x=parent)
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x = self.root
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return x, (x.parent if x else None)
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def _delete_rebalance(
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self, node: Optional[Node[T]], parent: Optional[Node[T]]
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) -> None:
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if not node and not parent:
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return
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logger.debug(
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"RB-Delete: Called with node=‹%s› parent=‹%s›", node, parent
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)
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logger.debug("RB-Delete: Colour of node: %s", colour(node))
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if (node and 2 not in Node.differences(node)) or (
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2 not in Node.differences(parent)
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):
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# we haven't deleted a black node
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logger.debug(
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"RB-Delete: No black node has been deleted; node: %s; diffs: %s",
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node,
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Node.differences(node),
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)
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return
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logger.debug("RB-Delete: Tree before rebalancing:\n%s", str(self))
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while node != self.root and colour(node) == Colour.Black:
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logger.debug(
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"RB-Delete: Rebalancing node=‹%s› (%s-node) parent=‹%s› (%s-node)",
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node,
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Node.differences(node),
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parent,
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Node.differences(parent),
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)
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if node == parent.left:
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node, parent = self._delete_rebalance_step(
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node,
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parent.right,
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parent,
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lambda x: x.left,
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lambda x: x.right,
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Node.rotate_left,
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Node.rotate_right,
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)
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else:
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node, parent = self._delete_rebalance_step(
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node,
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parent.left,
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parent,
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lambda x: x.right,
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lambda x: x.left,
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Node.rotate_right,
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Node.rotate_left,
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)
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# endregion DeleteRebalance
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@ -1,6 +1,7 @@
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from avl import AVLTree
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from wavl import WAVLTree
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from ravl import RAVLTree
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from rbt import RBTree
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import logging
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import random
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@ -13,8 +14,7 @@ logger = logging.getLogger(__name__)
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@pytest.mark.parametrize(
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("RankBalancedTree"),
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[AVLTree, WAVLTree, RAVLTree]
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("RankBalancedTree"), [RBTree, AVLTree, WAVLTree, RAVLTree]
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)
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@hypothesis.settings(max_examples=10000)
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@hypothesis.given(values=st.sets(st.integers()))
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@ -44,8 +44,7 @@ def _report(t_before: str, t_after: str) -> None:
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@pytest.mark.parametrize(
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("RankBalancedTree"),
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[AVLTree, WAVLTree, RAVLTree]
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("RankBalancedTree"), [RBTree, AVLTree, WAVLTree, RAVLTree]
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)
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@hypothesis.settings(max_examples=10000)
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@hypothesis.given(config=delete_strategy())
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