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