| /* |
| * 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. |
| */ |
| package org.apache.jackrabbit.oak.spi.query.fulltext; |
| |
| /** |
| * A pattern matcher. |
| */ |
| public class LikePattern { |
| |
| // TODO LIKE: optimize condition to '=' when no patterns are used, or 'between x and x+1' |
| // TODO LIKE: what to do for invalid patterns (patterns ending with a backslash) |
| |
| private static final int MATCH = 0, ONE = 1, ANY = 2; |
| |
| private String patternString; |
| private boolean invalidPattern; |
| private char[] patternChars; |
| private int[] patternTypes; |
| private int patternLength; |
| private String lowerBounds, upperBound; |
| |
| public LikePattern(String pattern) { |
| initPattern(pattern); |
| initBounds(); |
| } |
| |
| public boolean matches(String value) { |
| return !invalidPattern && compareAt(value, 0, 0, value.length(), patternChars, patternTypes); |
| } |
| |
| private static boolean compare(char[] pattern, String s, int pi, int si) { |
| return pattern[pi] == s.charAt(si); |
| } |
| |
| private boolean compareAt(String s, int pi, int si, int sLen, char[] pattern, int[] types) { |
| for (; pi < patternLength; pi++) { |
| int type = types[pi]; |
| switch (type) { |
| case MATCH: |
| if (si >= sLen || !compare(pattern, s, pi, si++)) { |
| return false; |
| } |
| break; |
| case ONE: |
| if (si++ >= sLen) { |
| return false; |
| } |
| break; |
| case ANY: |
| if (++pi >= patternLength) { |
| return true; |
| } |
| while (si < sLen) { |
| if (compare(pattern, s, pi, si) && compareAt(s, pi, si, sLen, pattern, types)) { |
| return true; |
| } |
| si++; |
| } |
| return false; |
| default: |
| throw new IllegalArgumentException("Internal error: " + type); |
| } |
| } |
| return si == sLen; |
| } |
| |
| private void initPattern(String p) { |
| patternLength = 0; |
| if (p == null) { |
| patternTypes = null; |
| patternChars = null; |
| return; |
| } |
| int len = p.length(); |
| patternChars = new char[len]; |
| patternTypes = new int[len]; |
| boolean lastAny = false; |
| for (int i = 0; i < len; i++) { |
| char c = p.charAt(i); |
| int type; |
| if (c == '\\') { |
| if (i >= len - 1) { |
| invalidPattern = true; |
| return; |
| } |
| c = p.charAt(++i); |
| type = MATCH; |
| lastAny = false; |
| } else if (c == '%') { |
| if (lastAny) { |
| continue; |
| } |
| type = ANY; |
| lastAny = true; |
| } else if (c == '_') { |
| type = ONE; |
| } else { |
| type = MATCH; |
| lastAny = false; |
| } |
| patternTypes[patternLength] = type; |
| patternChars[patternLength++] = c; |
| } |
| for (int i = 0; i < patternLength - 1; i++) { |
| if (patternTypes[i] == ANY && patternTypes[i + 1] == ONE) { |
| patternTypes[i] = ONE; |
| patternTypes[i + 1] = ANY; |
| } |
| } |
| patternString = new String(patternChars, 0, patternLength); |
| } |
| |
| @Override |
| public String toString() { |
| return patternString; |
| } |
| |
| /** |
| * Get the lower bound if any. |
| * |
| * @return return the lower bound, or null if unbound |
| */ |
| public String getLowerBound() { |
| return lowerBounds; |
| } |
| |
| /** |
| * Get the upper bound if any. |
| * |
| * @return return the upper bound, or null if unbound |
| */ |
| public String getUpperBound() { |
| return upperBound; |
| } |
| |
| private void initBounds() { |
| if (invalidPattern) { |
| return; |
| } |
| if (patternLength <= 0 || patternTypes[0] != MATCH) { |
| // can't use an index |
| return; |
| } |
| int maxMatch = 0; |
| StringBuilder buff = new StringBuilder(); |
| while (maxMatch < patternLength && patternTypes[maxMatch] == MATCH) { |
| buff.append(patternChars[maxMatch++]); |
| } |
| String lower = buff.toString(); |
| if (lower.isEmpty()) { |
| return; |
| } |
| if (maxMatch == patternLength) { |
| lowerBounds = upperBound = lower; |
| return; |
| } |
| lowerBounds = lower; |
| char next = lower.charAt(lower.length() - 1); |
| // search the 'next' unicode character (or at least a character |
| // that is higher) |
| for (int i = 1; i < 2000; i++) { |
| String upper = lower.substring(0, lower.length() - 1) + (char) (next + i); |
| if (upper.compareTo(lower) > 0) { |
| upperBound = upper; |
| return; |
| } |
| } |
| } |
| |
| } |