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// Copyright ©2014 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package uid implements unique ID provision for graphs.
package uid
import (
"math"
"gonum.org/v1/gonum/graph/internal/set"
)
// Max is the maximum ID value.
const Max = math.MaxInt64
// Set implements available ID storage.
type Set struct {
maxID int64
used, free set.Ints[int64]
}
// NewSet returns a new Set.
func NewSet() *Set {
return &Set{maxID: -1, used: make(set.Ints[int64]), free: make(set.Ints[int64])}
}
// NewID returns a new unique ID. The ID returned is not considered used
// until passed in a call to use.
func (s *Set) NewID() int64 {
for id := range s.free {
return id
}
if s.maxID != math.MaxInt64 {
return s.maxID + 1
}
for id := int64(0); id <= s.maxID; id++ {
if !s.used.Has(id) {
return id
}
}
panic("unreachable")
}
// Use adds the id to the used IDs in the Set.
func (s *Set) Use(id int64) {
s.used.Add(id)
s.free.Remove(id)
if id > s.maxID {
s.maxID = id
}
}
// Release frees the id for reuse.
func (s *Set) Release(id int64) {
s.free.Add(id)
s.used.Remove(id)
}
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