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Lucene example source code file (TermBuffer.java)

This example Lucene source code file (TermBuffer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

cloneable, clonenotsupportedexception, io, ioexception, lucene-510, object, override, string, string, term, term, termbuffer, termbuffer, utf8, utf8

The Lucene TermBuffer.java source code

package org.apache.lucene.index;

/**
 * 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.
 */

import java.io.IOException;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.UnicodeUtil;

final class TermBuffer implements Cloneable {

  private String field;
  private Term term;                            // cached
  private boolean preUTF8Strings;                // true if strings are stored in modified UTF8 encoding (LUCENE-510)
  private boolean dirty;                          // true if text was set externally (ie not read via UTF8 bytes)

  private UnicodeUtil.UTF16Result text = new UnicodeUtil.UTF16Result();
  private UnicodeUtil.UTF8Result bytes = new UnicodeUtil.UTF8Result();

  public final int compareTo(TermBuffer other) {
    if (field == other.field) 	  // fields are interned
      return compareChars(text.result, text.length, other.text.result, other.text.length);
    else
      return field.compareTo(other.field);
  }

  private static final int compareChars(char[] chars1, int len1,
                                        char[] chars2, int len2) {
    final int end = len1 < len2 ? len1:len2;
    for (int k = 0; k < end; k++) {
      char c1 = chars1[k];
      char c2 = chars2[k];
      if (c1 != c2) {
        return c1 - c2;
      }
    }
    return len1 - len2;
  }

  /** Call this if the IndexInput passed to {@link #read}
   *  stores terms in the "modified UTF8" (pre LUCENE-510)
   *  format. */
  void setPreUTF8Strings() {
    preUTF8Strings = true;
  }

  public final void read(IndexInput input, FieldInfos fieldInfos)
    throws IOException {
    this.term = null;                           // invalidate cache
    int start = input.readVInt();
    int length = input.readVInt();
    int totalLength = start + length;
    if (preUTF8Strings) {
      text.setLength(totalLength);
      input.readChars(text.result, start, length);
    } else {

      if (dirty) {
        // Fully convert all bytes since bytes is dirty
        UnicodeUtil.UTF16toUTF8(text.result, 0, text.length, bytes);
        bytes.setLength(totalLength);
        input.readBytes(bytes.result, start, length);
        UnicodeUtil.UTF8toUTF16(bytes.result, 0, totalLength, text);
        dirty = false;
      } else {
        // Incrementally convert only the UTF8 bytes that are new:
        bytes.setLength(totalLength);
        input.readBytes(bytes.result, start, length);
        UnicodeUtil.UTF8toUTF16(bytes.result, start, length, text);
      }
    }
    this.field = fieldInfos.fieldName(input.readVInt());
  }

  public final void set(Term term) {
    if (term == null) {
      reset();
      return;
    }
    final String termText = term.text();
    final int termLen = termText.length();
    text.setLength(termLen);
    termText.getChars(0, termLen, text.result, 0);
    dirty = true;
    field = term.field();
    this.term = term;
  }

  public final void set(TermBuffer other) {
    text.copyText(other.text);
    dirty = true;
    field = other.field;
    term = other.term;
  }

  public void reset() {
    field = null;
    text.setLength(0);
    term = null;
    dirty = true;
  }

  public Term toTerm() {
    if (field == null)                            // unset
      return null;

    if (term == null)
      term = new Term(field, new String(text.result, 0, text.length), false);

    return term;
  }

  @Override
  protected Object clone() {
    TermBuffer clone = null;
    try {
      clone = (TermBuffer)super.clone();
    } catch (CloneNotSupportedException e) {}

    clone.dirty = true;
    clone.bytes = new UnicodeUtil.UTF8Result();
    clone.text = new UnicodeUtil.UTF16Result();
    clone.text.copyText(text);
    return clone;
  }
}

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