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trie.go
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trie.go
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// Copyright 2019 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 trie
import (
"fmt"
"log"
"strings"
"github.com/saltbo/gopkg/safemap"
)
const (
defaultDelimiter = "/"
defaultWildcard = ".+"
)
// Trie is a tree
type Tree struct {
delimiter string
root *Node
}
// New returns a new Trie object.
func New() *Tree {
return &Tree{
delimiter: defaultDelimiter,
root: NewNode(),
}
}
// SetDelimiter sets the delimiter of the trie object.
func (trie *Tree) SetDelimiter(delimiter string) {
trie.delimiter = delimiter
}
func (trie *Tree) splitPattern(pattern string) []string {
p := strings.TrimRight(pattern, trie.delimiter)
parts := strings.Split(p, trie.delimiter)
if parts[0] == "" {
parts[0] = string(pattern[0])
}
return parts
}
func (trie *Tree) Dump() {
log.Printf("--------- Tree Dump ------------\n")
log.Printf("-%s: %v \n", trie.root.Key, trie.root.entry)
lastNode := trie.root
lastNode.dump("")
log.Printf("--------- Tree Dump End ----------\n\n")
}
func (trie *Tree) Empty() bool {
if !trie.root.Children.Empty() {
return false
} else if trie.root.entry != nil {
return false
}
return true
}
func (trie *Tree) Exist(pattern string) (interface{}, bool) {
node := trie.root
parts := trie.splitPattern(pattern)[1:]
for _, part := range parts {
if child, ok := node.directChild(part); ok {
node = child
continue
}
return nil, false
}
if node.entry == nil {
return nil, false
}
return node.entry, true
}
func (trie *Tree) Put(pattern string, entry interface{}) {
node := trie.root
parts := trie.splitPattern(pattern)[1:]
for _, part := range parts {
node = node.insertChild(part)
}
node.entry = entry
}
func (trie *Tree) Match(pattern string) (interface{}, bool) {
node := trie.root
parts := trie.splitPattern(pattern)[1:]
for _, part := range parts {
if child, ok := node.directChild(part); ok {
node = child
} else if wildcardNode, ok := node.wildcardChild(part); ok {
return wildcardNode.entry, true
} else {
goto traverseParent
}
}
if node.entry != nil {
return node.entry, true
}
traverseParent:
if wildcardNode, ok := node.wildcardParent(); ok {
return wildcardNode.entry, true
}
return nil, false
}
func (trie *Tree) Del(pattern string) error {
node := trie.root
parts := trie.splitPattern(pattern)[1:]
for _, part := range parts {
if child, ok := node.directChild(part); ok {
node = child
} else {
return fmt.Errorf("pattern %v is in not existed", pattern)
}
}
// 删除当前节点entry
node.entry = nil
// 判断当前节点是否有子节点,如果有则直接返回,如果没有子节点则执行向上遍历清理逻辑
if !node.Children.Empty() {
return nil
}
// 向上遍历查找上游节点是否为空节点,如果是则一并清理
for node.Parent != nil {
if node.Children.Empty() && node.entry == nil {
node.delete()
}
node = node.Parent
}
return nil
}
// Node is the tree node of the Trie.
type Node struct {
Key string
Parent *Node
Children *safemap.Map //nodeKey => Node
entry interface{}
}
func NewNode() *Node {
node := &Node{
Key: "/",
Children: safemap.New(),
}
return node
}
// return a child
func (n *Node) insertChild(part string) *Node {
if v, ok := n.Children.Load(part); ok {
return v.(*Node)
}
newNode := &Node{Key: part, Parent: n, Children: safemap.New()} //创建新节点
n.Children.Store(part, newNode)
return newNode
}
func (n *Node) directChild(part string) (*Node, bool) {
if v, ok := n.Children.Load(part); ok {
return v.(*Node), true
}
return nil, false
}
func (n *Node) wildcardChild(part string) (*Node, bool) {
if wildcardNode, ok := n.Children.Load(part + defaultWildcard); ok {
return wildcardNode.(*Node), true
} else if wildcardNode, ok := n.Children.Load(defaultWildcard); ok {
return wildcardNode.(*Node), true
}
return nil, false
}
// 向上遍历父节点是否存在通配路由
func (n *Node) wildcardParent() (*Node, bool) {
parentNode := n.Parent
for parentNode != nil {
if wildcardNode, ok := parentNode.Children.Load(defaultWildcard); ok {
return wildcardNode.(*Node), true
}
parentNode = parentNode.Parent
}
return nil, false
}
// delete a child
func (n *Node) delete() {
n.Parent.Children.Delete(n.Key)
}
func (n *Node) dump(format string) {
if format == "" {
format = "|--%s: %v \n"
}
n.Children.Range(func(k string, v interface{}) bool {
node := v.(*Node)
log.Printf(format, node.Key, node.entry)
if node.Children.Empty() {
return true
}
node.dump(" " + format)
return true
})
}