trie.go

Documentation: k8s.io/kube-openapi/pkg/util

     1  /*
     2  Copyright 2016 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package util
    18  
    19  // A simple trie implementation with Add and HasPrefix methods only.
    20  type Trie struct {
    21  	children map[byte]*Trie
    22  	wordTail bool
    23  	word     string
    24  }
    25  
    26  // NewTrie creates a Trie and add all strings in the provided list to it.
    27  func NewTrie(list []string) Trie {
    28  	ret := Trie{
    29  		children: make(map[byte]*Trie),
    30  		wordTail: false,
    31  	}
    32  	for _, v := range list {
    33  		ret.Add(v)
    34  	}
    35  	return ret
    36  }
    37  
    38  // Add adds a word to this trie
    39  func (t *Trie) Add(v string) {
    40  	root := t
    41  	for _, b := range []byte(v) {
    42  		child, exists := root.children[b]
    43  		if !exists {
    44  			child = &Trie{
    45  				children: make(map[byte]*Trie),
    46  				wordTail: false,
    47  			}
    48  			root.children[b] = child
    49  		}
    50  		root = child
    51  	}
    52  	root.wordTail = true
    53  	root.word = v
    54  }
    55  
    56  // HasPrefix returns true of v has any of the prefixes stored in this trie.
    57  func (t *Trie) HasPrefix(v string) bool {
    58  	_, has := t.GetPrefix(v)
    59  	return has
    60  }
    61  
    62  // GetPrefix is like HasPrefix but return the prefix in case of match or empty string otherwise.
    63  func (t *Trie) GetPrefix(v string) (string, bool) {
    64  	root := t
    65  	if root.wordTail {
    66  		return root.word, true
    67  	}
    68  	for _, b := range []byte(v) {
    69  		child, exists := root.children[b]
    70  		if !exists {
    71  			return "", false
    72  		}
    73  		if child.wordTail {
    74  			return child.word, true
    75  		}
    76  		root = child
    77  	}
    78  	return "", false
    79  }
    80
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