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pub mod internal_details {
use crate::{Augment, Unit, alloc_proxy::proxy::Allocator, node::internal_details::NodeRef};
/// A policy that defines how to compute and maintain augmented statistics for a Red-Black Tree.
pub trait TreePolicy {
/// The type of keys in the tree.
type K;
/// The type of values in the tree.
type V;
/// The type of augmented statistics stored in each node.
type S;
/// The augmentation type that defines how to compute the stats.
type G: Augment<Self::K, Self::V, Stats = Self::S>;
/// The allocator type used for node allocation.
type A: Allocator;
/// Computes the augmented statistics for a node based on its key, value, and the stats of its children.
fn compute(
key: &Self::K,
value: &Self::V,
left: Option<(&Self::K, &Self::V, &Self::S)>,
right: Option<(&Self::K, &Self::V, &Self::S)>,
) -> Self::S;
/// Updates the augmented statistics for a node based on its key, value, and the stats of its children.
fn augment(node: NodeRef<Self::K, Self::V, Self::S>);
/// Updates the augmented statistics for a node and all its ancestors up to the root.
fn augment_upstream(node: NodeRef<Self::K, Self::V, Self::S>);
}
/// A strategy that performs full augmentation, computing stats for each node.
/// This is the default strategy used by `AugmentedRBTree`.
#[derive(Debug)]
pub struct FullAugmentationStrategy;
/// A strategy that performs no augmentation, leaving stats uninitialized.
/// This is the default strategy used by `RBTree`.
#[derive(Debug)]
pub struct NullAugmentationStrategy;
/// A default tree policy that uses the provided augmentation type `G` and allocator `A`.
#[derive(Debug)]
pub struct DefaultTraitPolicy<K, V, G, S, A, AS> {
_marker: core::marker::PhantomData<fn() -> (K, V, G, S, A, AS)>,
}
impl<K, V, G, S, A> TreePolicy for DefaultTraitPolicy<K, V, G, S, A, FullAugmentationStrategy>
where
K: Ord,
G: Augment<K, V, Stats = S>,
A: Allocator,
{
type K = K;
type V = V;
type S = S;
type G = G;
type A = A;
fn compute(
key: &Self::K,
value: &Self::V,
left: Option<(&Self::K, &Self::V, &Self::S)>,
right: Option<(&Self::K, &Self::V, &Self::S)>,
) -> Self::S {
G::compute(key, value, left, right)
}
fn augment(node: NodeRef<Self::K, Self::V, Self::S>) {
unsafe {
let raw_node = node.ptr.as_ptr();
let left_ptr = (*raw_node).left;
let right_ptr = (*raw_node).right;
let left_args = if let Some(l) = left_ptr {
let l_ptr = l.as_ptr();
Some((&(*l_ptr).key, &(*l_ptr).value, &(*l_ptr).stats))
} else {
None
};
let right_args = if let Some(r) = right_ptr {
let r_ptr = r.as_ptr();
Some((&(*r_ptr).key, &(*r_ptr).value, &(*r_ptr).stats))
} else {
None
};
(*raw_node).stats =
G::compute(&(*raw_node).key, &(*raw_node).value, left_args, right_args);
}
}
fn augment_upstream(node: NodeRef<Self::K, Self::V, Self::S>) {
let mut ptr = node;
while let Some(parent) = ptr.parent() {
Self::augment(parent);
ptr = parent;
}
}
}
impl<K, V, A> TreePolicy for DefaultTraitPolicy<K, V, Unit, (), A, NullAugmentationStrategy>
where
K: Ord,
A: Allocator,
{
type K = K;
type V = V;
type S = ();
type G = Unit;
type A = A;
#[cfg_attr(coverage_nightly, coverage(off))]
fn compute(
_key: &Self::K,
_value: &Self::V,
_left: Option<(&Self::K, &Self::V, &Self::S)>,
_right: Option<(&Self::K, &Self::V, &Self::S)>,
) -> Self::S {
}
fn augment(_node: NodeRef<Self::K, Self::V, Self::S>) {}
fn augment_upstream(_node: NodeRef<Self::K, Self::V, Self::S>) {}
}
}