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    1   /*
    2    * This file is part of dependency-check-core.
    3    *
    4    * Dependency-check-core is free software: you can redistribute it and/or modify it
    5    * under the terms of the GNU General Public License as published by the Free
    6    * Software Foundation, either version 3 of the License, or (at your option) any
    7    * later version.
    8    *
    9    * Dependency-check-core is distributed in the hope that it will be useful, but
    10   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11   * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
    12   * details.
    13   *
    14   * You should have received a copy of the GNU General Public License along with
    15   * dependency-check-core. If not, see http://www.gnu.org/licenses/.
    16   *
    17   * Copyright (c) 2012 Jeremy Long. All Rights Reserved.
    18   */
    19  package org.owasp.dependencycheck.data.lucene;
    20
    21  import java.io.IOException;
    22  import java.util.LinkedList;
    23  import org.apache.lucene.analysis.TokenFilter;
    24  import org.apache.lucene.analysis.TokenStream;
    25  import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
    26
    27  /**
    28   * <p>Takes a TokenStream and adds additional tokens by concatenating pairs of
    29   * words.</p>
    30   * <p><b>Example:</b> "Spring Framework Core" -> "Spring SpringFramework
    31   * Framework FrameworkCore Core".</p>
    32   *
    33   * @author Jeremy Long (jeremy.long@owasp.org)
    34   */
    35  public final class TokenPairConcatenatingFilter extends TokenFilter {
    36
    37      /**
    38       * The char term attribute.
    39       */
    40      private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    41      /**
    42       * The previous word parsed.
    43       */
    44      private String previousWord;
    45      /**
    46       * A list of words parsed.
    47       */
    48      private final LinkedList<String> words;
    49
    50      /**
    51       * Returns the previous word. This is needed in the test cases.
    52       *
    53       * @return te previous word
    54       */
    55      protected String getPreviousWord() {
    56          return previousWord;
    57      }
    58
    59      /**
    60       * Returns the words list. This is needed in the test cases.
    61       *
    62       * @return the words list
    63       */
    64      protected LinkedList<String> getWords() {
    65          return words;
    66      }
    67
    68      /**
    69       * Constructs a new TokenPairConcatenatingFilter.
    70       *
    71       * @param stream the TokenStream that this filter will process
    72       */
    73      public TokenPairConcatenatingFilter(TokenStream stream) {
    74          super(stream);
    75          words = new LinkedList<String>();
    76      }
    77
    78      /**
    79       * Increments the underlying TokenStream and sets CharTermAttributes to
    80       * construct an expanded set of tokens by concatenating tokens with the
    81       * previous token.
    82       *
    83       * @return whether or not we have hit the end of the TokenStream
    84       * @throws IOException is thrown when an IOException occurs
    85       */
    86      @Override
    87      public boolean incrementToken() throws IOException {
    88
    89          //collect all the terms into the words collection
    90          while (input.incrementToken()) {
    91              final String word = new String(termAtt.buffer(), 0, termAtt.length());
    92              words.add(word);
    93          }
    94
    95          //if we have a previousTerm - write it out as its own token concatenated
    96          // with the current word (if one is available).
    97          if (previousWord != null && words.size() > 0) {
    98              final String word = words.getFirst();
    99              clearAttributes();
    100             termAtt.append(previousWord).append(word);
    101             previousWord = null;
    102             return true;
    103         }
    104         //if we have words, write it out as a single token
    105         if (words.size() > 0) {
    106             final String word = words.removeFirst();
    107             clearAttributes();
    108             termAtt.append(word);
    109             previousWord = word;
    110             return true;
    111         }
    112         return false;
    113     }
    114
    115     /**
    116      * <p>Resets the Filter and clears any internal state data that may have
    117      * been left-over from previous uses of the Filter.</p>
    118      * <p><b>If this Filter is re-used this method must be called between
    119      * uses.</b></p>
    120      */
    121     public void clear() {
    122         previousWord = null;
    123         words.clear();
    124     }
    125 }