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// Copyright 2015 The Go 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 ssa
// from https://research.swtch.com/sparse
// in turn, from Briggs and Torczon
type sparseSet struct {
dense []ID
sparse []int32
}
// newSparseSet returns a sparseSet that can represent
// integers between 0 and n-1.
func newSparseSet(n int) *sparseSet {
return &sparseSet{dense: nil, sparse: make([]int32, n)}
}
func (s *sparseSet) cap() int {
return len(s.sparse)
}
func (s *sparseSet) size() int {
return len(s.dense)
}
func (s *sparseSet) contains(x ID) bool {
i := s.sparse[x]
return i < int32(len(s.dense)) && s.dense[i] == x
}
func (s *sparseSet) add(x ID) {
i := s.sparse[x]
if i < int32(len(s.dense)) && s.dense[i] == x {
return
}
s.dense = append(s.dense, x)
s.sparse[x] = int32(len(s.dense)) - 1
}
func (s *sparseSet) addAll(a []ID) {
for _, x := range a {
s.add(x)
}
}
func (s *sparseSet) addAllValues(a []*Value) {
for _, v := range a {
s.add(v.ID)
}
}
func (s *sparseSet) remove(x ID) {
i := s.sparse[x]
if i < int32(len(s.dense)) && s.dense[i] == x {
y := s.dense[len(s.dense)-1]
s.dense[i] = y
s.sparse[y] = i
s.dense = s.dense[:len(s.dense)-1]
}
}
// pop removes an arbitrary element from the set.
// The set must be nonempty.
func (s *sparseSet) pop() ID {
x := s.dense[len(s.dense)-1]
s.dense = s.dense[:len(s.dense)-1]
return x
}
func (s *sparseSet) clear() {
s.dense = s.dense[:0]
}
func (s *sparseSet) contents() []ID {
return s.dense
}
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