Algorithms/red-black-tree-0.rs
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Redesigned balancing without explicit using stack

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This commit is contained in:
Andrew Golovashevich 2025-12-29 20:57:25 +03:00
parent 2303585d5e
commit 1dd64086db
1 changed files with 47 additions and 43 deletions
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90
src/algo/add.rs
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@ -173,43 +173,53 @@ fn _add_recursive<Ctx: AddRecContext>(
}
}
unsafe { balance(ctx, stack) }
unsafe { balance(ctx) }
}
trait BalancingContext: RedBlackTreeColorContext {
fn getLeftDirectedContext(&mut self) -> impl DirectedBalancingContext<NodeRef = Self::NodeRef>;
fn getRightDirectedContext(&mut self)
-> impl DirectedBalancingContext<NodeRef = Self::NodeRef>;
fn stackPopParentInfo(&self) -> Option<Frame<Self::NodeRef>>;
}
trait DirectedBalancingContext:
RedBlackTreeColorContext + DirectedBinaryTreeChildrenGetterContext
{
fn rotateForward_Forward(&mut self, parent: Self::NodeRef, pivot: Self::NodeRef);
fn rotateOpposite(
&mut self,
parent: Option<(Self::NodeRef, BinaryTreeDirection)>,
pivot: Self::NodeRef,
);
}
trait BalancingContext: RedBlackTreeColorContext {
fn getLeftDirectedContext(&mut self) -> impl DirectedBalancingContext<NodeRef = Self::NodeRef>;
fn getRightDirectedContext(&mut self)
-> impl DirectedBalancingContext<NodeRef = Self::NodeRef>;
fn rotateOpposite_GrandParent(&mut self, pivot: Self::NodeRef);
}
unsafe fn balance<Ctx: BalancingContext>(ctx: &mut Ctx, stack: &mut Stack<Frame<Ctx::NodeRef>>) {
fn balance<Ctx: BalancingContext>(ctx: &mut Ctx) {
loop {
if ctx.getColor(stack.getParent().node.clone()) == Color::BLACK {
break;
let parent;
match ctx.stackPopParentInfo() {
None => return,
Some(_parent) => parent = _parent,
}
if !stack.hasGrandParent() {
ctx.setColor(stack.getParent().node.clone(), Color::BLACK);
if ctx.getColor(parent.node.clone()) == Color::BLACK {
break;
}
match stack.getGrandParent().dir {
let grandparent;
match ctx.stackPopParentInfo() {
None => {
ctx.setColor(parent.node.clone(), Color::BLACK);
break;
}
Some(_grandparent) => grandparent = _grandparent,
}
match grandparent.dir {
BinaryTreeDirection::LEFT => {
if _directed(&mut ctx.getLeftDirectedContext(), stack) {
if _directed(&mut ctx.getLeftDirectedContext(), grandparent, parent) {
break;
}
}
BinaryTreeDirection::RIGHT => {
if _directed(&mut ctx.getRightDirectedContext(), stack) {
if _directed(&mut ctx.getRightDirectedContext(), grandparent, parent) {
break;
}
}
@ -217,40 +227,34 @@ unsafe fn balance<Ctx: BalancingContext>(ctx: &mut Ctx, stack: &mut Stack<Frame<
fn _directed<Ctx: DirectedBalancingContext>(
ctx: &mut Ctx,
stack: &mut Stack<Frame<Ctx::NodeRef>>,
grandparent: Frame<Ctx::NodeRef>,
parent: Frame<Ctx::NodeRef>,
) -> bool {
let uncle = ctx.getOppositeChild(stack.getGrandParent().node.clone());
let uncle = ctx.getOppositeChild(grandparent.node.clone());
if let Some(uncle) = uncle {
if ctx.getColor(uncle.clone()) == Color::RED {
ctx.setColor(stack.getParent().node.clone(), Color::BLACK);
ctx.setColor(parent.node.clone(), Color::BLACK);
ctx.setColor(uncle, Color::BLACK);
ctx.setColor(stack.getGrandParent().node.clone(), Color::RED);
ctx.setColor(grandparent.node.clone(), Color::RED);
if !stack.hasGrandGrandParent() {
return true;
}
stack.popDiscard();
stack.popDiscard();
return false;
}
}
if stack.getGrandParent().dir != stack.getParent().dir {
ctx.rotateForward_Forward(
stack.getGrandParent().node.clone(),
stack.getParent().node.clone(),
);
stack.replaceTop(Frame {
node: stack.getParent().node.clone(),
dir: stack.getGrandParent().dir,
})
let normalizedParent;
if grandparent.dir != parent.dir {
normalizedParent = Frame {
node: ctx.getOppositeChild(parent.node.clone()).unwrap(),
dir: grandparent.dir,
};
ctx.rotateForward_Forward(grandparent.node.clone(), parent.node.clone());
let _ = parent;
} else {
normalizedParent = parent;
}
ctx.setColor(stack.getParent().node.clone(), Color::BLACK);
ctx.setColor(stack.getGrandParent().node.clone(), Color::RED);
ctx.rotateOpposite(
stack.getGrandGrandParent().map(|f| (f.node.clone(), f.dir)),
stack.getGrandParent().node.clone(),
);
ctx.setColor(normalizedParent.node.clone(), Color::BLACK);
ctx.setColor(grandparent.node.clone(), Color::RED);
ctx.rotateOpposite_GrandParent(grandparent.node.clone());
return true;
}