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120 lines
2.5 KiB
Go
120 lines
2.5 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// Package trie implements a simple trie tree for minio server/tools borrows
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// idea from - https://godoc.org/golang.org/x/text/internal/triegen.
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package trie
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// Node trie tree node container carries value and children.
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type Node struct {
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exists bool
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value string
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child map[rune]*Node // runes as child.
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}
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// newNode create a new trie node.
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func newNode() *Node {
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return &Node{
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exists: false,
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value: "",
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child: make(map[rune]*Node),
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}
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}
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// Trie is a trie container.
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type Trie struct {
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root *Node
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size int
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}
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// Root returns root node.
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func (t *Trie) Root() *Node {
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return t.root
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}
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// Insert insert a key.
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func (t *Trie) Insert(key string) {
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curNode := t.root
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for _, v := range key {
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if curNode.child[v] == nil {
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curNode.child[v] = newNode()
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}
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curNode = curNode.child[v]
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}
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if !curNode.exists {
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// increment when new rune child is added.
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t.size++
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curNode.exists = true
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}
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// value is stored for retrieval in future.
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curNode.value = key
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}
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// PrefixMatch - prefix match.
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func (t *Trie) PrefixMatch(key string) []string {
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node, _ := t.findNode(key)
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if node == nil {
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return nil
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}
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return t.Walk(node)
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}
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// Walk the tree.
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func (t *Trie) Walk(node *Node) (ret []string) {
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if node.exists {
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ret = append(ret, node.value)
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}
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for _, v := range node.child {
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ret = append(ret, t.Walk(v)...)
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}
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return
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}
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// find nodes corresponding to key.
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func (t *Trie) findNode(key string) (node *Node, index int) {
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curNode := t.root
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f := false
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for k, v := range key {
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if f {
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index = k
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f = false
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}
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if curNode.child[v] == nil {
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return nil, index
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}
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curNode = curNode.child[v]
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if curNode.exists {
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f = true
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}
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}
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if curNode.exists {
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index = len(key)
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}
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return curNode, index
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}
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// NewTrie create a new trie.
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func NewTrie() *Trie {
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return &Trie{
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root: newNode(),
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size: 0,
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}
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}
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