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    1   package org.apache.lucene.document;
    2   
    3   /**
    4    * Licensed to the Apache Software Foundation (ASF) under one or more
    5    * contributor license agreements.  See the NOTICE file distributed with
    6    * this work for additional information regarding copyright ownership.
    7    * The ASF licenses this file to You under the Apache License, Version 2.0
    8    * (the "License"); you may not use this file except in compliance with
    9    * the License.  You may obtain a copy of the License at
   10    *
   11    *     http://www.apache.org/licenses/LICENSE-2.0
   12    *
   13    * Unless required by applicable law or agreed to in writing, software
   14    * distributed under the License is distributed on an "AS IS" BASIS,
   15    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   16    * See the License for the specific language governing permissions and
   17    * limitations under the License.
   18    */
   19   
   20   import java.util.*;             // for javadoc
   21   import org.apache.lucene.search.ScoreDoc; // for javadoc
   22   import org.apache.lucene.search.Searcher;  // for javadoc
   23   import org.apache.lucene.index.IndexReader;  // for javadoc
   24   
   25   /** Documents are the unit of indexing and search.
   26    *
   27    * A Document is a set of fields.  Each field has a name and a textual value.
   28    * A field may be {@link Fieldable#isStored() stored} with the document, in which
   29    * case it is returned with search hits on the document.  Thus each document
   30    * should typically contain one or more stored fields which uniquely identify
   31    * it.
   32    *
   33    * <p>Note that fields which are <i>not</i> {@link Fieldable#isStored() stored} are
   34    * <i>not</i> available in documents retrieved from the index, e.g. with {@link
   35    * ScoreDoc#doc}, {@link Searcher#doc(int)} or {@link
   36    * IndexReader#document(int)}.
   37    */
   38   
   39   public final class Document implements java.io.Serializable {
   40     List fields = new ArrayList();
   41     private float boost = 1.0f;
   42   
   43     /** Constructs a new document with no fields. */
   44     public Document() {}
   45   
   46   
   47     /** Sets a boost factor for hits on any field of this document.  This value
   48      * will be multiplied into the score of all hits on this document.
   49      *
   50      * <p>The default value is 1.0.
   51      * 
   52      * <p>Values are multiplied into the value of {@link Fieldable#getBoost()} of
   53      * each field in this document.  Thus, this method in effect sets a default
   54      * boost for the fields of this document.
   55      *
   56      * @see Fieldable#setBoost(float)
   57      */
   58     public void setBoost(float boost) {
   59       this.boost = boost;
   60     }
   61   
   62     /** Returns, at indexing time, the boost factor as set by {@link #setBoost(float)}. 
   63      *
   64      * <p>Note that once a document is indexed this value is no longer available
   65      * from the index.  At search time, for retrieved documents, this method always 
   66      * returns 1. This however does not mean that the boost value set at  indexing 
   67      * time was ignored - it was just combined with other indexing time factors and 
   68      * stored elsewhere, for better indexing and search performance. (For more 
   69      * information see the "norm(t,d)" part of the scoring formula in 
   70      * {@link org.apache.lucene.search.Similarity Similarity}.)
   71      *
   72      * @see #setBoost(float)
   73      */
   74     public float getBoost() {
   75       return boost;
   76     }
   77   
   78     /**
   79      * <p>Adds a field to a document.  Several fields may be added with
   80      * the same name.  In this case, if the fields are indexed, their text is
   81      * treated as though appended for the purposes of search.</p>
   82      * <p> Note that add like the removeField(s) methods only makes sense 
   83      * prior to adding a document to an index. These methods cannot
   84      * be used to change the content of an existing index! In order to achieve this,
   85      * a document has to be deleted from an index and a new changed version of that
   86      * document has to be added.</p>
   87      */
   88     public final void add(Fieldable field) {
   89       fields.add(field);
   90     }
   91     
   92     /**
   93      * <p>Removes field with the specified name from the document.
   94      * If multiple fields exist with this name, this method removes the first field that has been added.
   95      * If there is no field with the specified name, the document remains unchanged.</p>
   96      * <p> Note that the removeField(s) methods like the add method only make sense 
   97      * prior to adding a document to an index. These methods cannot
   98      * be used to change the content of an existing index! In order to achieve this,
   99      * a document has to be deleted from an index and a new changed version of that
  100      * document has to be added.</p>
  101      */
  102     public final void removeField(String name) {
  103       Iterator it = fields.iterator();
  104       while (it.hasNext()) {
  105         Fieldable field = (Fieldable)it.next();
  106         if (field.name().equals(name)) {
  107           it.remove();
  108           return;
  109         }
  110       }
  111     }
  112     
  113     /**
  114      * <p>Removes all fields with the given name from the document.
  115      * If there is no field with the specified name, the document remains unchanged.</p>
  116      * <p> Note that the removeField(s) methods like the add method only make sense 
  117      * prior to adding a document to an index. These methods cannot
  118      * be used to change the content of an existing index! In order to achieve this,
  119      * a document has to be deleted from an index and a new changed version of that
  120      * document has to be added.</p>
  121      */
  122     public final void removeFields(String name) {
  123       Iterator it = fields.iterator();
  124       while (it.hasNext()) {
  125         Fieldable field = (Fieldable)it.next();
  126         if (field.name().equals(name)) {
  127           it.remove();
  128         }
  129       }
  130     }
  131   
  132     /** Returns a field with the given name if any exist in this document, or
  133      * null.  If multiple fields exists with this name, this method returns the
  134      * first value added.
  135      * Do not use this method with lazy loaded fields.
  136      */
  137     public final Field getField(String name) {
  138       for (int i = 0; i < fields.size(); i++) {
  139         Field field = (Field)fields.get(i);
  140         if (field.name().equals(name))
  141           return field;
  142       }
  143       return null;
  144     }
  145   
  146   
  147    /** Returns a field with the given name if any exist in this document, or
  148      * null.  If multiple fields exists with this name, this method returns the
  149      * first value added.
  150      */
  151    public Fieldable getFieldable(String name) {
  152      for (int i = 0; i < fields.size(); i++) {
  153        Fieldable field = (Fieldable)fields.get(i);
  154        if (field.name().equals(name))
  155          return field;
  156      }
  157      return null;
  158    }
  159   
  160     /** Returns the string value of the field with the given name if any exist in
  161      * this document, or null.  If multiple fields exist with this name, this
  162      * method returns the first value added. If only binary fields with this name
  163      * exist, returns null.
  164      */
  165     public final String get(String name) {
  166       for (int i = 0; i < fields.size(); i++) {
  167         Fieldable field = (Fieldable)fields.get(i);
  168         if (field.name().equals(name) && (!field.isBinary()))
  169           return field.stringValue();
  170       }
  171       return null;
  172     }
  173   
  174     /** Returns an Enumeration of all the fields in a document.
  175      * @deprecated use {@link #getFields()} instead
  176      */
  177     public final Enumeration fields() {
  178       return new Enumeration() {
  179         final Iterator iter = fields.iterator();
  180         public boolean hasMoreElements() {
  181           return iter.hasNext();
  182         }
  183         public Object nextElement() {
  184           return iter.next();
  185         }
  186       };
  187     }
  188   
  189     /** Returns a List of all the fields in a document.
  190      * <p>Note that fields which are <i>not</i> {@link Fieldable#isStored() stored} are
  191      * <i>not</i> available in documents retrieved from the
  192      * index, e.g. {@link Searcher#doc(int)} or {@link
  193      * IndexReader#document(int)}.
  194      */
  195     public final List getFields() {
  196       return fields;
  197     }
  198   
  199     private final static Field[] NO_FIELDS = new Field[0];
  200     
  201     /**
  202      * Returns an array of {@link Field}s with the given name.
  203      * Do not use with lazy loaded fields.
  204      * This method returns an empty array when there are no
  205      * matching fields.  It never returns null.
  206      *
  207      * @param name the name of the field
  208      * @return a <code>Field[]</code> array
  209      */
  210      public final Field[] getFields(String name) {
  211        List result = new ArrayList();
  212        for (int i = 0; i < fields.size(); i++) {
  213          Field field = (Field)fields.get(i);
  214          if (field.name().equals(name)) {
  215            result.add(field);
  216          }
  217        }
  218   
  219        if (result.size() == 0)
  220          return NO_FIELDS;
  221   
  222        return (Field[])result.toArray(new Field[result.size()]);
  223      }
  224   
  225   
  226      private final static Fieldable[] NO_FIELDABLES = new Fieldable[0];
  227   
  228      /**
  229      * Returns an array of {@link Fieldable}s with the given name.
  230      * This method returns an empty array when there are no
  231      * matching fields.  It never returns null.
  232      *
  233      * @param name the name of the field
  234      * @return a <code>Fieldable[]</code> array
  235      */
  236      public Fieldable[] getFieldables(String name) {
  237        List result = new ArrayList();
  238        for (int i = 0; i < fields.size(); i++) {
  239          Fieldable field = (Fieldable)fields.get(i);
  240          if (field.name().equals(name)) {
  241            result.add(field);
  242          }
  243        }
  244   
  245        if (result.size() == 0)
  246          return NO_FIELDABLES;
  247   
  248        return (Fieldable[])result.toArray(new Fieldable[result.size()]);
  249      }
  250   
  251   
  252      private final static String[] NO_STRINGS = new String[0];
  253   
  254     /**
  255      * Returns an array of values of the field specified as the method parameter.
  256      * This method returns an empty array when there are no
  257      * matching fields.  It never returns null.
  258      * @param name the name of the field
  259      * @return a <code>String[]</code> of field values
  260      */
  261     public final String[] getValues(String name) {
  262       List result = new ArrayList();
  263       for (int i = 0; i < fields.size(); i++) {
  264         Fieldable field = (Fieldable)fields.get(i);
  265         if (field.name().equals(name) && (!field.isBinary()))
  266           result.add(field.stringValue());
  267       }
  268       
  269       if (result.size() == 0)
  270         return NO_STRINGS;
  271       
  272       return (String[])result.toArray(new String[result.size()]);
  273     }
  274   
  275     private final static byte[][] NO_BYTES = new byte[0][];
  276   
  277     /**
  278     * Returns an array of byte arrays for of the fields that have the name specified
  279     * as the method parameter.  This method returns an empty
  280     * array when there are no matching fields.  It never
  281     * returns null.
  282     *
  283     * @param name the name of the field
  284     * @return a <code>byte[][]</code> of binary field values
  285     */
  286     public final byte[][] getBinaryValues(String name) {
  287       List result = new ArrayList();
  288       for (int i = 0; i < fields.size(); i++) {
  289         Fieldable field = (Fieldable)fields.get(i);
  290         if (field.name().equals(name) && (field.isBinary()))
  291           result.add(field.binaryValue());
  292       }
  293     
  294       if (result.size() == 0)
  295         return NO_BYTES;
  296     
  297       return (byte[][])result.toArray(new byte[result.size()][]);
  298     }
  299     
  300     /**
  301     * Returns an array of bytes for the first (or only) field that has the name
  302     * specified as the method parameter. This method will return <code>null</code>
  303     * if no binary fields with the specified name are available.
  304     * There may be non-binary fields with the same name.
  305     *
  306     * @param name the name of the field.
  307     * @return a <code>byte[]</code> containing the binary field value or <code>null</code>
  308     */
  309     public final byte[] getBinaryValue(String name) {
  310       for (int i=0; i < fields.size(); i++) {
  311         Fieldable field = (Fieldable)fields.get(i);
  312         if (field.name().equals(name) && (field.isBinary()))
  313           return field.binaryValue();
  314       }
  315       return null;
  316     }
  317     
  318     /** Prints the fields of a document for human consumption. */
  319     public final String toString() {
  320       StringBuffer buffer = new StringBuffer();
  321       buffer.append("Document<");
  322       for (int i = 0; i < fields.size(); i++) {
  323         Fieldable field = (Fieldable)fields.get(i);
  324         buffer.append(field.toString());
  325         if (i != fields.size()-1)
  326           buffer.append(" ");
  327       }
  328       buffer.append(">");
  329       return buffer.toString();
  330     }
  331   }

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