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/*
* Copyright (C) 2010 The Libphonenumber Authors
*
* 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 com.google.i18n.phonenumbers.internal;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.regex.Pattern;
/**
* LRU Cache for compiled regular expressions used by the libphonenumbers libary.
*
* @author Shaopeng Jia
*/
public class RegexCache {
private LRUCache<String, Pattern> cache;
public RegexCache(int size) {
cache = new LRUCache<String, Pattern>(size);
}
public Pattern getPatternForRegex(String regex) {
Pattern pattern = cache.get(regex);
if (pattern == null) {
pattern = Pattern.compile(regex);
cache.put(regex, pattern);
}
return pattern;
}
// @VisibleForTesting
boolean containsRegex(String regex) {
return cache.containsKey(regex);
}
private static class LRUCache<K, V> {
// LinkedHashMap offers a straightforward implementation of LRU cache.
private LinkedHashMap<K, V> map;
private int size;
@SuppressWarnings("serial")
public LRUCache(int size) {
this.size = size;
// Using access-order instead of insertion-order.
map = new LinkedHashMap<K, V>(size * 4 / 3 + 1, 0.75f, true) {
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > LRUCache.this.size;
}
};
}
public synchronized V get(K key) {
return map.get(key);
}
public synchronized void put(K key, V value) {
map.put(key, value);
}
public synchronized boolean containsKey(K key) {
return map.containsKey(key);
}
}
}
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