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From "Andrew C. Oliver" <acoli...@apache.org>
Subject proposed changes to document (doug) vs AbstractDocument (pt 1/3)
Date Sat, 09 Feb 2002 13:20:13 GMT
--------------------NEW------------AbstractDocument.java

package org.apache.lucene.document;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.util.Enumeration;

/** 
 * Documents are the unit of indexing and search.
 *
 * A Document is a set of fields.  Each field has a name and a textual value.
 * A field may be stored with the document, in which case it is returned with
 * search hits on the document.  Thus each document should typically contain
 * stored fields which uniquely identify it.
 *
 * This Abstract Document provides the interface and internal field collections
 * for use in Documents.
 *
 * @author  Doug Cutting?
 * @author  Andrew C. Oliver (acoliver@users.sourceforge.net)
 */
public abstract class AbstractDocument {
    DocumentFieldList fieldList = null;    
    
    /** Creates a new instance of AbstractDocument */
    public AbstractDocument() {
    }
    
  /** Adds a field to a document.  Several fields may be added with
   * the same name.  In this case, if the fields are indexed, their text is
   * treated as though appended for the purposes of search. */    
    public void add(Field field) {
      fieldList = new DocumentFieldList(field, fieldList);
    }
    
  /** Returns a field with the given name if any exist in this document, or
    null.  If multiple fields may exist with this name, this method returns the
    last added such added. */    
  public Field getField(String name) {
    for (DocumentFieldList list = fieldList; list != null; list = list.next)
      if (list.field.name().equals(name))
	return list.field;
    return null;
  }

    
  /** Returns the string value of the field with the given name if any exist in
    this document, or null.  If multiple fields may exist with this name, this
    method returns the last added such added. */
  public String get(String name) {
    Field field = getField(name);
    if (field != null)
      return field.stringValue();
    else
      return null;
  }

    
  /** Returns an Enumeration of all the fields in a document. */    
  public Enumeration fields() {
    return new DocumentFieldEnumeration(this);
  }

  public String toString() {
    StringBuffer buffer = new StringBuffer();
    buffer.append("Document<");
    for (DocumentFieldList list = fieldList; list != null; list = list.next) {
      buffer.append(list.field.toString());
      if (list.next != null)
	buffer.append(" ");
    }
    buffer.append(">");
    return buffer.toString();
  }
  
  
    
    final class DocumentFieldList {
      DocumentFieldList(Field f, DocumentFieldList n) {
        field = f;
        next = n;
      }
      Field field;
      DocumentFieldList next;
    }

    final class DocumentFieldEnumeration implements Enumeration {
      DocumentFieldList fields;
      DocumentFieldEnumeration(AbstractDocument d) {
            fields = d.fieldList;
      }

      public final boolean hasMoreElements() {
            return fields == null ? false : true;
      }

      public final Object nextElement() {
            Field result = fields.field;
            fields = fields.next;
            return result;
        }
      }    
}

-- 
www.superlinksoftware.com
www.sourceforge.net/projects/poi - port of Excel format to java
http://developer.java.sun.com/developer/bugParade/bugs/4487555.html 
			- fix java generics!


The avalanche has already started. It is too late for the pebbles to
vote.
-Ambassador Kosh


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