minio/trie.go

112 lines
2.3 KiB
Go

/*
* Minio Cloud Storage, (C) 2015 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 main
// This package borrows idea from - https://godoc.org/golang.org/x/text/internal/triegen
// Trie trie container
type Trie struct {
root *trieNode
size int
}
// newTrie get new trie
func newTrie() *Trie {
return &Trie{
root: newTrieNode(),
size: 0,
}
}
// trieNode trie tree node container carries value and children
type trieNode struct {
exists bool
value interface{}
child map[rune]*trieNode // runes as child
}
func newTrieNode() *trieNode {
return &trieNode{
exists: false,
value: nil,
child: make(map[rune]*trieNode),
}
}
// 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] = newTrieNode()
}
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 *trieNode) (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 *trieNode, 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
}