go biasedsparsemap 源码
golang biasedsparsemap 代码
文件路径：/src/cmd/compile/internal/ssa/biasedsparsemap.go
// Copyright 2018 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
import (
"cmd/internal/src"
"math"
)
// A biasedSparseMap is a sparseMap for integers between J and K inclusive,
// where J might be somewhat larger than zero (and K-J is probably much smaller than J).
// (The motivating use case is the line numbers of statements for a single function.)
// Not all features of a SparseMap are exported, and it is also easy to treat a
// biasedSparseMap like a SparseSet.
type biasedSparseMap struct {
s *sparseMap
first int
}
// newBiasedSparseMap returns a new biasedSparseMap for values between first and last, inclusive.
func newBiasedSparseMap(first, last int) *biasedSparseMap {
if first > last {
return &biasedSparseMap{first: math.MaxInt32, s: nil}
}
return &biasedSparseMap{first: first, s: newSparseMap(1 + last - first)}
}
// cap returns one more than the largest key valid for s
func (s *biasedSparseMap) cap() int {
if s == nil || s.s == nil {
return 0
}
return s.s.cap() + int(s.first)
}
// size returns the number of entries stored in s
func (s *biasedSparseMap) size() int {
if s == nil || s.s == nil {
return 0
}
return s.s.size()
}
// contains reports whether x is a key in s
func (s *biasedSparseMap) contains(x uint) bool {
if s == nil || s.s == nil {
return false
}
if int(x) < s.first {
return false
}
if int(x) >= s.cap() {
return false
}
return s.s.contains(ID(int(x) - s.first))
}
// get returns the value s maps for key x, or -1 if
// x is not mapped or is out of range for s.
func (s *biasedSparseMap) get(x uint) int32 {
if s == nil || s.s == nil {
return -1
}
if int(x) < s.first {
return -1
}
if int(x) >= s.cap() {
return -1
}
return s.s.get(ID(int(x) - s.first))
}
// getEntry returns the i'th key and value stored in s,
// where 0 <= i < s.size()
func (s *biasedSparseMap) getEntry(i int) (x uint, v int32) {
e := s.s.contents()[i]
x = uint(int(e.key) + s.first)
v = e.val
return
}
// add inserts x->0 into s, provided that x is in the range of keys stored in s.
func (s *biasedSparseMap) add(x uint) {
if int(x) < s.first || int(x) >= s.cap() {
return
}
s.s.set(ID(int(x)-s.first), 0, src.NoXPos)
}
// add inserts x->v into s, provided that x is in the range of keys stored in s.
func (s *biasedSparseMap) set(x uint, v int32) {
if int(x) < s.first || int(x) >= s.cap() {
return
}
s.s.set(ID(int(x)-s.first), v, src.NoXPos)
}
// remove removes key x from s.
func (s *biasedSparseMap) remove(x uint) {
if int(x) < s.first || int(x) >= s.cap() {
return
}
s.s.remove(ID(int(x) - s.first))
}
func (s *biasedSparseMap) clear() {
if s.s != nil {
s.s.clear()
}
}
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