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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *  http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17
    18  package org.apache.any23.filter;
    19
    20  import org.apache.any23.extractor.ExtractionContext;
    21  import org.apache.any23.extractor.html.TitleExtractor;
    22  import org.apache.any23.extractor.html.TitleExtractorFactory;
    23  import org.apache.any23.writer.TripleHandler;
    24  import org.apache.any23.writer.TripleHandlerException;
    25  import org.eclipse.rdf4j.model.Resource;
    26  import org.eclipse.rdf4j.model.IRI;
    27  import org.eclipse.rdf4j.model.Value;
    28
    29  /**
    30   * A {@link TripleHandler} that suppresses output of the {@link TitleExtractor} unless some other triples could be
    31   * parsed from the document. This is used when we don't want to have single-triple RDF documents around that contain
    32   * only the title triple.
    33   *
    34   * @author Richard Cyganiak (richard@cyganiak.de)
    35   */
    36  public class IgnoreTitlesOfEmptyDocuments implements TripleHandler {
    37
    38      private final ExtractionContextBlocker blocker;
    39
    40      public IgnoreTitlesOfEmptyDocuments(TripleHandler wrapped) {
    41          blocker = new ExtractionContextBlocker(wrapped);
    42      }
    43
    44      public void startDocument(IRI documentIRI) throws TripleHandlerException {
    45          blocker.startDocument(documentIRI);
    46      }
    47
    48      public void openContext(ExtractionContext context) throws TripleHandlerException {
    49          blocker.openContext(context);
    50          if (isTitleContext(context)) {
    51              blocker.blockContext(context);
    52          }
    53      }
    54
    55      public void receiveTriple(Resource s, IRI p, Value o, IRI g, ExtractionContext context)
    56              throws TripleHandlerException {
    57          if (!isTitleContext(context)) {
    58              blocker.unblockDocument();
    59          }
    60          blocker.receiveTriple(s, p, o, g, context);
    61      }
    62
    63      public void receiveNamespace(String prefix, String uri, ExtractionContext context) throws TripleHandlerException {
    64          blocker.receiveNamespace(prefix, uri, context);
    65      }
    66
    67      public void closeContext(ExtractionContext context) {
    68          blocker.closeContext(context);
    69      }
    70
    71      public void close() throws TripleHandlerException {
    72          blocker.close();
    73      }
    74
    75      private boolean isTitleContext(ExtractionContext context) {
    76          return context.getExtractorName().equals(TitleExtractorFactory.NAME);
    77      }
    78
    79      public void endDocument(IRI documentIRI) throws TripleHandlerException {
    80          blocker.endDocument(documentIRI);
    81      }
    82
    83      public void setContentLength(long contentLength) {
    84          // Ignore.
    85      }
    86  }