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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package containers
type interval[K Ordered[K]] struct {
Min, Max K
}
// Compare implements Ordered.
func (a interval[K]) Compare(b interval[K]) int {
if d := a.Min.Compare(b.Min); d != 0 {
return d
}
return a.Max.Compare(b.Max)
}
// ContainsFn returns whether this interval contains the range matched
// by the given function.
func (ival interval[K]) ContainsFn(fn func(K) int) bool {
return fn(ival.Min) >= 0 && fn(ival.Max) <= 0
}
type intervalValue[K Ordered[K], V any] struct {
Val V
ValSpan interval[K]
ChildSpan interval[K]
}
// Compare implements Ordered.
func (a intervalValue[K, V]) Compare(b intervalValue[K, V]) int {
return a.ValSpan.Compare(b.ValSpan)
}
type IntervalTree[K Ordered[K], V any] struct {
MinFn func(V) K
MaxFn func(V) K
inner RBTree[intervalValue[K, V]]
}
func (*IntervalTree[K, V]) attrFn(node *RBNode[intervalValue[K, V]]) {
max := node.Value.ValSpan.Max
if node.Left != nil && node.Left.Value.ChildSpan.Max.Compare(max) > 0 {
max = node.Left.Value.ChildSpan.Max
}
if node.Right != nil && node.Right.Value.ChildSpan.Max.Compare(max) > 0 {
max = node.Right.Value.ChildSpan.Max
}
node.Value.ChildSpan.Max = max
min := node.Value.ValSpan.Min
if node.Left != nil && node.Left.Value.ChildSpan.Min.Compare(min) < 0 {
min = node.Left.Value.ChildSpan.Min
}
if node.Right != nil && node.Right.Value.ChildSpan.Min.Compare(min) < 0 {
min = node.Right.Value.ChildSpan.Min
}
node.Value.ChildSpan.Min = min
}
func (t *IntervalTree[K, V]) init() {
if t.inner.AttrFn == nil {
t.inner.AttrFn = t.attrFn
}
}
func (t *IntervalTree[K, V]) Equal(u *IntervalTree[K, V]) bool {
return t.inner.Equal(&u.inner)
}
func (t *IntervalTree[K, V]) Insert(val V) {
t.init()
t.inner.Insert(intervalValue[K, V]{
Val: val,
ValSpan: interval[K]{
Min: t.MinFn(val),
Max: t.MaxFn(val),
},
})
}
func (t *IntervalTree[K, V]) Min() (K, bool) {
if t.inner.root == nil {
var zero K
return zero, false
}
return t.inner.root.Value.ChildSpan.Min, true
}
func (t *IntervalTree[K, V]) Max() (K, bool) {
if t.inner.root == nil {
var zero K
return zero, false
}
return t.inner.root.Value.ChildSpan.Max, true
}
func (t *IntervalTree[K, V]) Search(fn func(K) int) (V, bool) {
node := t.inner.root
for node != nil {
switch {
case node.Value.ValSpan.ContainsFn(fn):
return node.Value.Val, true
case node.Left != nil && node.Left.Value.ChildSpan.ContainsFn(fn):
node = node.Left
case node.Right != nil && node.Right.Value.ChildSpan.ContainsFn(fn):
node = node.Right
default:
node = nil
}
}
var zero V
return zero, false
}
func (t *IntervalTree[K, V]) Range(fn func(V) bool) {
t.inner.Range(func(node *RBNode[intervalValue[K, V]]) bool {
return fn(node.Value.Val)
})
}
func (t *IntervalTree[K, V]) Subrange(rangeFn func(K) int, handleFn func(V) bool) {
t.subrange(t.inner.root, rangeFn, handleFn)
}
func (t *IntervalTree[K, V]) subrange(node *RBNode[intervalValue[K, V]], rangeFn func(K) int, handleFn func(V) bool) bool {
if node == nil {
return true
}
if !node.Value.ChildSpan.ContainsFn(rangeFn) {
return true
}
if !t.subrange(node.Left, rangeFn, handleFn) {
return false
}
if node.Value.ValSpan.ContainsFn(rangeFn) {
if !handleFn(node.Value.Val) {
return false
}
}
if !t.subrange(node.Right, rangeFn, handleFn) {
return false
}
return true
}
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