| /* |
| * 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.iotdb.tsfile.utils; |
| |
| import java.util.regex.Pattern; |
| import java.util.regex.PatternSyntaxException; |
| |
| public class RegexUtils { |
| |
| private RegexUtils() { |
| // util class |
| } |
| |
| /** |
| * The main idea of this part comes from |
| * https://codereview.stackexchange.com/questions/36861/convert-sql-like-to-regex/36864 |
| */ |
| public static String parseLikePatternToRegex(String likePattern) { |
| String unescapeValue = unescapeString(likePattern); |
| String specialRegexStr = ".^$*+?{}[]|()"; |
| StringBuilder patternStrBuild = new StringBuilder(); |
| patternStrBuild.append("^"); |
| for (int i = 0; i < unescapeValue.length(); i++) { |
| String ch = String.valueOf(unescapeValue.charAt(i)); |
| if (specialRegexStr.contains(ch)) { |
| ch = "\\" + unescapeValue.charAt(i); |
| } |
| if (i == 0 |
| || !"\\".equals(String.valueOf(unescapeValue.charAt(i - 1))) |
| || i >= 2 |
| && "\\\\" |
| .equals( |
| patternStrBuild.substring( |
| patternStrBuild.length() - 2, patternStrBuild.length()))) { |
| String replaceStr = ch.replace("%", ".*?").replace("_", "."); |
| patternStrBuild.append(replaceStr); |
| } else { |
| patternStrBuild.append(ch); |
| } |
| } |
| patternStrBuild.append("$"); |
| return patternStrBuild.toString(); |
| } |
| |
| // This Method is for un-escaping strings except '\' before special string '%', '_', '\', because |
| // we need to use '\' to judge whether to replace this to regexp string |
| private static String unescapeString(String value) { |
| StringBuilder stringBuilder = new StringBuilder(); |
| int curIndex = 0; |
| while (curIndex < value.length()) { |
| String ch = String.valueOf(value.charAt(curIndex)); |
| if ("\\".equals(ch) && curIndex < value.length() - 1) { |
| String nextChar = String.valueOf(value.charAt(curIndex + 1)); |
| if ("%".equals(nextChar) || "_".equals(nextChar) || "\\".equals(nextChar)) { |
| stringBuilder.append(ch); |
| if ("\\".equals(nextChar)) { |
| curIndex++; |
| } |
| } |
| } else { |
| stringBuilder.append(ch); |
| } |
| curIndex++; |
| } |
| return stringBuilder.toString(); |
| } |
| |
| public static Pattern compileRegex(String regex) { |
| try { |
| return Pattern.compile(regex); |
| } catch (PatternSyntaxException e) { |
| throw new PatternSyntaxException("Illegal regex expression: ", regex, e.getIndex()); |
| } |
| } |
| } |