| /* |
| * 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.olingo.server.core.etag; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.Set; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| |
| /** |
| * <p>Parses the values of HTTP header fields that contain a list of entity tags or a |
| * single star character, i.e., <code>If-Match</code> and <code>If-None-Match</code>.</p> |
| * <p>See <a href="https://www.ietf.org/rfc/rfc7232.txt">RFC 7232</a> for details; |
| * there the following grammar is defined:</p> |
| * <pre> |
| * If-Match = "*" / 1#entity-tag |
| * If-None-Match = "*" / 1#entity-tag |
| * entity-tag = [ weak ] opaque-tag |
| * weak = %x57.2F ; "W/", case-sensitive |
| * opaque-tag = DQUOTE *etagc DQUOTE |
| * etagc = %x21 / %x23-7E / %x80-FF |
| * </pre> |
| * <p>Values with illegal syntax do not contribute to the result but no exception is thrown.</p> |
| */ |
| public class ETagParser { |
| |
| private static final Pattern ETAG = Pattern.compile("\\s*(,\\s*)+|((?:W/)?\"[!#-~\\x80-\\xFF]*\")"); |
| |
| private ETagParser() { |
| // Private constructor for utility classes |
| } |
| |
| protected static Collection<String> parse(final Collection<String> values) { |
| if (values == null) { |
| return Collections.<String> emptySet(); |
| } |
| |
| Set<String> result = new HashSet<>(); |
| for (final String value : values) { |
| final Collection<String> part = parse(value); |
| if (part.size() == 1 && "*".equals(part.iterator().next())) { |
| return part; |
| } else { |
| result.addAll(part); |
| } |
| } |
| return result; |
| } |
| |
| private static Collection<String> parse(final String value) { |
| if ("*".equals(value.trim())) { |
| return Collections.singleton("*"); |
| } else { |
| Set<String> result = new HashSet<>(); |
| String separator = ""; |
| int start = 0; |
| Matcher matcher = ETAG.matcher(value.trim()); |
| while (matcher.find() && matcher.start() == start) { |
| start = matcher.end(); |
| if (matcher.group(1) != null) { |
| separator = matcher.group(1); |
| } else if (separator != null) { |
| result.add(matcher.group(2)); |
| separator = null; |
| } else { |
| return Collections.<String> emptySet(); |
| } |
| } |
| return matcher.hitEnd() ? result : Collections.<String> emptySet(); |
| } |
| } |
| } |