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Copy pathtrie.go
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118 lines (105 loc) · 2.44 KB
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/*
* Minio Cloud Storage, (C) 2014, 2015, 2016, 2017 Minio, Inc.
*
* 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 trie implements a simple trie tree for minio server/tools borrows
// idea from - https://godoc.org/golang.org/x/text/internal/triegen.
package trie
// Node trie tree node container carries value and children.
type Node struct {
exists bool
value interface{}
child map[rune]*Node // runes as child.
}
// newNode create a new trie node.
func newNode() *Node {
return &Node{
exists: false,
value: nil,
child: make(map[rune]*Node),
}
}
// Trie is a trie container.
type Trie struct {
root *Node
size int
}
// Root returns root node.
func (t *Trie) Root() *Node {
return t.root
}
// Insert insert a key.
func (t *Trie) Insert(key string) {
curNode := t.root
for _, v := range key {
if curNode.child[v] == nil {
curNode.child[v] = newNode()
}
curNode = curNode.child[v]
}
if !curNode.exists {
// increment when new rune child is added.
t.size++
curNode.exists = true
}
// value is stored for retrieval in future.
curNode.value = key
}
// PrefixMatch - prefix match.
func (t *Trie) PrefixMatch(key string) []interface{} {
node, _ := t.findNode(key)
if node != nil {
return t.Walk(node)
}
return []interface{}{}
}
// Walk the tree.
func (t *Trie) Walk(node *Node) (ret []interface{}) {
if node.exists {
ret = append(ret, node.value)
}
for _, v := range node.child {
ret = append(ret, t.Walk(v)...)
}
return
}
// find nodes corresponding to key.
func (t *Trie) findNode(key string) (node *Node, index int) {
curNode := t.root
f := false
for k, v := range key {
if f {
index = k
f = false
}
if curNode.child[v] == nil {
return nil, index
}
curNode = curNode.child[v]
if curNode.exists {
f = true
}
}
if curNode.exists {
index = len(key)
}
return curNode, index
}
// NewTrie create a new trie.
func NewTrie() *Trie {
return &Trie{
root: newNode(),
size: 0,
}
}