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interval.go
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interval.go
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package bandit
import (
"errors"
"fmt"
)
type (
// Interval is an interval
Interval struct {
Tree
array [7]node
}
// BoundType is a bound type
BoundType uint8
)
const (
UnboundBound BoundType = iota
ClosedBound
OpenBound
)
const (
empty = "(Ø)"
infinite = "(-∞, ∞)"
)
var (
ErrInvalidInterval = errors.New("invalid interval")
boundmap = map[bool]string{
true: "[)",
false: "(]",
}
)
func NewInterval(lowerBound BoundType, lower, upper uint64, upperBound BoundType) (ival Interval) {
ival.nodes = ival.array[:1] // Fix malloc later; for now we're escaping
var (
lul, rul bool
left, right uint
)
switch lowerBound {
case UnboundBound:
lul = true
case OpenBound:
left = ival.node(lower, 0, 0, 0, true, false)
case ClosedBound:
left = ival.node(lower, 0, 0, 0, true, true)
}
switch upperBound {
case UnboundBound:
rul = true
case OpenBound:
right = ival.node(upper, 0, 0, 0, true, true)
rul = true
case ClosedBound:
right = ival.node(upper, 0, 0, 0, true, false)
rul = true
}
ival.mergeRoot(&ival.Tree, &ival.Tree, left, right, lul, rul, and)
return ival
}
func (ival Interval) Span() uint64 {
lidx, _ := ival.Tree.leftmostLeaf(ival.root, ival.ul)
ridx, _ := ival.Tree.rightmostLeaf(ival.root, ival.ul)
return (&ival.nodes[ridx]).prefix - (&ival.nodes[lidx]).prefix
}
func (ival Interval) Lower() uint64 {
idx, _ := ival.Tree.leftmostLeaf(ival.root, ival.ul)
return ival.nodes[idx].prefix
}
func (ival Interval) Upper() uint64 {
idx, _ := ival.Tree.rightmostLeaf(ival.root, ival.ul)
return ival.nodes[idx].prefix
}
func (ival Interval) AsIntervalSet() *IntervalSet {
copy(ival.array[:], ival.nodes)
ival.nodes = ival.array[:len(ival.nodes)]
return &IntervalSet{
Tree: ival.Tree,
}
}
func (ival Interval) String() string {
if ival.root == 0 {
if ival.ul {
return infinite
}
return empty
}
n := ival.nodes[ival.root]
if n.level == 0 {
// Half-unbounded interval or point
if n.boundBoth() {
return fmt.Sprintf("[%d]", n.prefix)
}
bs := boundmap[n.incl]
if ival.ul {
return fmt.Sprintf("(-∞, %d%c", n.prefix, bs[1])
}
return fmt.Sprintf("%c%d, ∞)", bs[0], n.prefix)
}
l, r := ival.nodes[n.left], ival.nodes[n.right]
lb, rb := boundmap[l.incl][0], boundmap[r.incl][1]
return fmt.Sprintf("%c%d, %d%c", lb, l.prefix, r.prefix, rb)
}
func (ival Interval) Intersection(other Interval) Interval {
// Update the slice to point to the array copy
ival.nodes = ival.array[:len(ival.nodes)]
// Merge onto the copy
ival.mergeRoot(&ival.Tree, &other.Tree, ival.root, other.root, ival.ul, other.ul, and)
return ival
}
func (ival Interval) Union(other Interval) Interval {
// Update the slice to point to the array copy
ival.nodes = ival.array[:len(ival.nodes)]
// Merge onto the copy
ival.mergeRoot(&ival.Tree, &other.Tree, ival.root, other.root, ival.ul, other.ul, or)
return ival
}
func (ival Interval) IsEmpty() bool {
return ival.root == 0 && !ival.ul
}
func (ival Interval) Equals(other Interval) bool {
return ival.ul == other.ul && treeEquals(&ival.Tree, &other.Tree, ival.root, other.root)
}
func LeftOpen(lower, upper uint64) Interval {
return NewInterval(OpenBound, lower, upper, ClosedBound)
}
func RightOpen(lower, upper uint64) Interval {
return NewInterval(ClosedBound, lower, upper, OpenBound)
}
func Closed(lower, upper uint64) Interval {
return NewInterval(ClosedBound, lower, upper, ClosedBound)
}
func Point(val uint64) Interval {
return Closed(val, val)
}
func Open(lower, upper uint64) Interval {
return NewInterval(OpenBound, lower, upper, OpenBound)
}
func Above(value uint64) Interval {
return NewInterval(OpenBound, value, 0, UnboundBound)
}
func AtOrAbove(value uint64) Interval {
return NewInterval(ClosedBound, value, 0, UnboundBound)
}
func Below(value uint64) Interval {
return NewInterval(UnboundBound, 0, value, OpenBound)
}
func AtOrBelow(value uint64) Interval {
return NewInterval(UnboundBound, 0, value, ClosedBound)
}
func Empty() (ival Interval) {
return NewInterval(OpenBound, 0, 0, OpenBound)
}
func Unbounded() (ival Interval) {
return NewInterval(UnboundBound, 0, 0, UnboundBound)
}