| package org.apache.lucene.util; |
| |
| import java.util.Comparator; |
| import java.util.StringTokenizer; |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| |
| /** |
| * Methods for manipulating strings. |
| * |
| * @lucene.internal |
| */ |
| public abstract class StringHelper { |
| |
| /** |
| * Compares two {@link BytesRef}, element by element, and returns the |
| * number of elements common to both arrays. |
| * |
| * @param left The first {@link BytesRef} to compare |
| * @param right The second {@link BytesRef} to compare |
| * @return The number of common elements. |
| */ |
| public static int bytesDifference(BytesRef left, BytesRef right) { |
| int len = left.length < right.length ? left.length : right.length; |
| final byte[] bytesLeft = left.bytes; |
| final int offLeft = left.offset; |
| byte[] bytesRight = right.bytes; |
| final int offRight = right.offset; |
| for (int i = 0; i < len; i++) |
| if (bytesLeft[i+offLeft] != bytesRight[i+offRight]) |
| return i; |
| return len; |
| } |
| |
| private StringHelper() { |
| } |
| |
| /** |
| * @return a Comparator over versioned strings such as X.YY.Z |
| * @lucene.internal |
| */ |
| public static Comparator<String> getVersionComparator() { |
| return versionComparator; |
| } |
| |
| private static Comparator<String> versionComparator = new Comparator<String>() { |
| @Override |
| public int compare(String a, String b) { |
| StringTokenizer aTokens = new StringTokenizer(a, "."); |
| StringTokenizer bTokens = new StringTokenizer(b, "."); |
| |
| while (aTokens.hasMoreTokens()) { |
| int aToken = Integer.parseInt(aTokens.nextToken()); |
| if (bTokens.hasMoreTokens()) { |
| int bToken = Integer.parseInt(bTokens.nextToken()); |
| if (aToken != bToken) { |
| return aToken < bToken ? -1 : 1; |
| } |
| } else { |
| // a has some extra trailing tokens. if these are all zeroes, thats ok. |
| if (aToken != 0) { |
| return 1; |
| } |
| } |
| } |
| |
| // b has some extra trailing tokens. if these are all zeroes, thats ok. |
| while (bTokens.hasMoreTokens()) { |
| if (Integer.parseInt(bTokens.nextToken()) != 0) |
| return -1; |
| } |
| |
| return 0; |
| } |
| }; |
| |
| public static boolean equals(String s1, String s2) { |
| if (s1 == null) { |
| return s2 == null; |
| } else { |
| return s1.equals(s2); |
| } |
| } |
| |
| /** |
| * Returns <code>true</code> iff the ref starts with the given prefix. |
| * Otherwise <code>false</code>. |
| * |
| * @param ref |
| * the {@link BytesRef} to test |
| * @param prefix |
| * the expected prefix |
| * @return Returns <code>true</code> iff the ref starts with the given prefix. |
| * Otherwise <code>false</code>. |
| */ |
| public static boolean startsWith(BytesRef ref, BytesRef prefix) { |
| return sliceEquals(ref, prefix, 0); |
| } |
| |
| /** |
| * Returns <code>true</code> iff the ref ends with the given suffix. Otherwise |
| * <code>false</code>. |
| * |
| * @param ref |
| * the {@link BytesRef} to test |
| * @param suffix |
| * the expected suffix |
| * @return Returns <code>true</code> iff the ref ends with the given suffix. |
| * Otherwise <code>false</code>. |
| */ |
| public static boolean endsWith(BytesRef ref, BytesRef suffix) { |
| return sliceEquals(ref, suffix, ref.length - suffix.length); |
| } |
| |
| private static boolean sliceEquals(BytesRef sliceToTest, BytesRef other, int pos) { |
| if (pos < 0 || sliceToTest.length - pos < other.length) { |
| return false; |
| } |
| int i = sliceToTest.offset + pos; |
| int j = other.offset; |
| final int k = other.offset + other.length; |
| |
| while (j < k) { |
| if (sliceToTest.bytes[i++] != other.bytes[j++]) { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| } |