View Javadoc

    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.extractor.html;
    19
    20  import java.io.IOException;
    21  import java.io.InputStream;
    22
    23  /**
    24   * Extension of {@link java.io.InputStream} meant to detect and replace any occurrence of inline <i>span</i>:
    25   *
    26   * <pre>
    27   * &lt;span/&gt;
    28   * </pre>
    29   *
    30   * with an open close tag sequence:
    31   *
    32   * <pre>
    33   * &lt;span&gt;&lt;/span&gt;
    34   * </pre>
    35   *
    36   * @author Michele Mostarda (mostarda@fbk.eu)
    37   */
    38  public class SpanCloserInputStream extends InputStream {
    39
    40      private static final String TRAILING_SEQUENCE_OPEN = "<span";
    41      private static final char TRAILING_SEQUENCE_CLOSE = '>';
    42      private static final String CLOSE_SEQUENCE = "</span>";
    43
    44      private final InputStream wrapped;
    45
    46      private int trailingSequenceOpenMatch = 0;
    47      private int closeSequenceIndex = 0;
    48      private boolean trailingSequenceOpenDetected = false;
    49      private boolean trailingSequenceCloseDetected = false;
    50      private boolean inlineDetected = false;
    51      private boolean betweenQuotes = false;
    52
    53      public SpanCloserInputStream(InputStream is) {
    54          wrapped = is;
    55      }
    56
    57      @Override
    58      public int read() throws IOException {
    59          if (trailingSequenceOpenDetected && inlineDetected && trailingSequenceCloseDetected) {
    60              final int ret = CLOSE_SEQUENCE.charAt(closeSequenceIndex);
    61              closeSequenceIndex++;
    62              if (closeSequenceIndex >= CLOSE_SEQUENCE.length()) {
    63                  resetDetector();
    64              }
    65              return ret;
    66          } else if (trailingSequenceOpenDetected && trailingSequenceCloseDetected) {
    67              resetDetector();
    68          }
    69
    70          int c = wrapped.read();
    71          if (c == '"') {
    72              betweenQuotes = !betweenQuotes;
    73          } else if (c == '/' && !betweenQuotes && trailingSequenceOpenDetected && !trailingSequenceCloseDetected) {
    74              inlineDetected = true;
    75              c = wrapped.read();
    76          }
    77
    78          if (!trailingSequenceOpenDetected && checkOpenTrailingSequence(c)) {
    79              trailingSequenceOpenDetected = true;
    80              trailingSequenceCloseDetected = false;
    81          } else if (c == TRAILING_SEQUENCE_CLOSE && trailingSequenceOpenDetected) {
    82              trailingSequenceCloseDetected = true;
    83          }
    84          return c;
    85      }
    86
    87      private boolean checkOpenTrailingSequence(int c) {
    88          if (TRAILING_SEQUENCE_OPEN.charAt(trailingSequenceOpenMatch) == Character.toLowerCase(c)) {
    89              trailingSequenceOpenMatch++;
    90              if (trailingSequenceOpenMatch == TRAILING_SEQUENCE_OPEN.length()) {
    91                  trailingSequenceOpenMatch = 0;
    92                  return true;
    93              }
    94          } else {
    95              trailingSequenceOpenMatch = 0;
    96          }
    97          return false;
    98      }
    99
    100     private void resetDetector() {
    101         trailingSequenceOpenMatch = 0;
    102         closeSequenceIndex = 0;
    103         trailingSequenceOpenDetected = false;
    104         trailingSequenceCloseDetected = false;
    105         inlineDetected = false;
    106         betweenQuotes = false;
    107     }
    108
    109 }