1 /* 2 * Copyright (C) 2010 The Libphonenumber 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 com.google.i18n.phonenumbers.internal; 18 19 import java.util.LinkedHashMap; 20 import java.util.Map; 21 import java.util.regex.Pattern; 22 23 /** 24 * LRU Cache for compiled regular expressions used by the libphonenumbers libary. 25 * 26 * @author Shaopeng Jia 27 */ 28 public class RegexCache { 29 private LRUCache<String, Pattern> cache; 30 31 public RegexCache(int size) { 32 cache = new LRUCache<String, Pattern>(size); 33 } 34 35 public Pattern getPatternForRegex(String regex) { 36 Pattern pattern = cache.get(regex); 37 if (pattern == null) { 38 pattern = Pattern.compile(regex); 39 cache.put(regex, pattern); 40 } 41 return pattern; 42 } 43 44 // @VisibleForTesting 45 boolean containsRegex(String regex) { 46 return cache.containsKey(regex); 47 } 48 49 private static class LRUCache<K, V> { 50 // LinkedHashMap offers a straightforward implementation of LRU cache. 51 private LinkedHashMap<K, V> map; 52 private int size; 53 54 @SuppressWarnings("serial") 55 public LRUCache(int size) { 56 this.size = size; 57 // Using access-order instead of insertion-order. 58 map = new LinkedHashMap<K, V>(size * 4 / 3 + 1, 0.75f, true) { 59 @Override 60 protected boolean removeEldestEntry(Map.Entry<K, V> eldest) { 61 return size() > LRUCache.this.size; 62 } 63 }; 64 } 65 66 public synchronized V get(K key) { 67 return map.get(key); 68 } 69 70 public synchronized void put(K key, V value) { 71 map.put(key, value); 72 } 73 74 public synchronized boolean containsKey(K key) { 75 return map.containsKey(key); 76 } 77 } 78 } 79
