/usr/share/gocode/src/github.com/cockroachdb/cmux/patricia.go is in golang-github-cockroachdb-cmux-dev 0.0~git20170110.0.30d10be-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 | // Copyright 2016 The CMux Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
package cmux
import (
"bytes"
"io"
)
// patriciaTree is a simple patricia tree that handles []byte instead of string
// and cannot be changed after instantiation.
type patriciaTree struct {
root *ptNode
maxDepth int // max depth of the tree.
}
func newPatriciaTree(bs ...[]byte) *patriciaTree {
max := 0
for _, b := range bs {
if max < len(b) {
max = len(b)
}
}
return &patriciaTree{
root: newNode(bs),
maxDepth: max + 1,
}
}
func newPatriciaTreeString(strs ...string) *patriciaTree {
b := make([][]byte, len(strs))
for i, s := range strs {
b[i] = []byte(s)
}
return newPatriciaTree(b...)
}
func (t *patriciaTree) matchPrefix(r io.Reader) bool {
buf := make([]byte, t.maxDepth)
n, _ := io.ReadFull(r, buf)
return t.root.match(buf[:n], true)
}
func (t *patriciaTree) match(r io.Reader) bool {
buf := make([]byte, t.maxDepth)
n, _ := io.ReadFull(r, buf)
return t.root.match(buf[:n], false)
}
type ptNode struct {
prefix []byte
next map[byte]*ptNode
terminal bool
}
func newNode(strs [][]byte) *ptNode {
if len(strs) == 0 {
return &ptNode{
prefix: []byte{},
terminal: true,
}
}
if len(strs) == 1 {
return &ptNode{
prefix: strs[0],
terminal: true,
}
}
p, strs := splitPrefix(strs)
n := &ptNode{
prefix: p,
}
nexts := make(map[byte][][]byte)
for _, s := range strs {
if len(s) == 0 {
n.terminal = true
continue
}
nexts[s[0]] = append(nexts[s[0]], s[1:])
}
n.next = make(map[byte]*ptNode)
for first, rests := range nexts {
n.next[first] = newNode(rests)
}
return n
}
func splitPrefix(bss [][]byte) (prefix []byte, rest [][]byte) {
if len(bss) == 0 || len(bss[0]) == 0 {
return prefix, bss
}
if len(bss) == 1 {
return bss[0], [][]byte{{}}
}
for i := 0; ; i++ {
var cur byte
eq := true
for j, b := range bss {
if len(b) <= i {
eq = false
break
}
if j == 0 {
cur = b[i]
continue
}
if cur != b[i] {
eq = false
break
}
}
if !eq {
break
}
prefix = append(prefix, cur)
}
rest = make([][]byte, 0, len(bss))
for _, b := range bss {
rest = append(rest, b[len(prefix):])
}
return prefix, rest
}
func (n *ptNode) match(b []byte, prefix bool) bool {
l := len(n.prefix)
if l > 0 {
if l > len(b) {
l = len(b)
}
if !bytes.Equal(b[:l], n.prefix) {
return false
}
}
if n.terminal && (prefix || len(n.prefix) == len(b)) {
return true
}
if l >= len(b) {
return false
}
nextN, ok := n.next[b[l]]
if !ok {
return false
}
if l == len(b) {
b = b[l:l]
} else {
b = b[l+1:]
}
return nextN.match(b, prefix)
}
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