/*
* Carrot2 project.
*
* Copyright (C) 2002-2014, Dawid Weiss, Stanisław Osiński.
* All rights reserved.
*
* Refer to the full license file "carrot2.LICENSE"
* in the root folder of the repository checkout or at:
* http://www.carrot2.org/carrot2.LICENSE
*/
package org.carrot2.text.preprocessing;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.lang.StringUtils;
import org.carrot2.core.Document;
import org.carrot2.core.ProcessingException;
import org.carrot2.core.attribute.Init;
import org.carrot2.text.analysis.ITokenizer;
import org.carrot2.text.preprocessing.PreprocessingContext.AllFields;
import org.carrot2.text.preprocessing.PreprocessingContext.AllTokens;
import org.carrot2.text.util.MutableCharArray;
import org.carrot2.util.CharArrayUtils;
import org.carrot2.util.ExceptionUtils;
import org.carrot2.util.attribute.Attribute;
import org.carrot2.util.attribute.AttributeLevel;
import org.carrot2.util.attribute.Bindable;
import org.carrot2.util.attribute.DefaultGroups;
import org.carrot2.util.attribute.Group;
import org.carrot2.util.attribute.Input;
import org.carrot2.util.attribute.Label;
import org.carrot2.util.attribute.Level;
import com.carrotsearch.hppc.ByteArrayList;
import com.carrotsearch.hppc.IntArrayList;
import com.carrotsearch.hppc.ShortArrayList;
import com.google.common.collect.Lists;
/**
* Performs tokenization of documents.
* <p>
* This class saves the following results to the {@link PreprocessingContext}:
* <ul>
* <li>{@link AllTokens#image}</li>
* <li>{@link AllTokens#documentIndex}</li>
* <li>{@link AllTokens#fieldIndex}</li>
* <li>{@link AllTokens#type}</li>
* </ul>
*/
@Bindable(prefix = "Tokenizer")
public final class Tokenizer
{
/**
* Textual fields of documents that should be tokenized and parsed for clustering.
*/
@Init
@Input
@Attribute
@Label("Document fields")
@Level(AttributeLevel.ADVANCED)
@Group(DefaultGroups.PREPROCESSING)
public Collection<String> documentFields = Arrays.asList(new String []
{
Document.TITLE, Document.SUMMARY
});
/**
* Token images.
*/
private ArrayList<char []> images;
/**
* An array of token types.
*
* @see ITokenizer
*/
private ShortArrayList tokenTypes;
/**
* An array of document indexes.
*/
private IntArrayList documentIndices;
/**
* An array of field indexes.
*
* @see AllFields
*/
private ByteArrayList fieldIndices;
/**
* Performs tokenization and saves the results to the <code>context</code>.
*/
public void tokenize(PreprocessingContext context)
{
// Documents to tokenize
final List<Document> documents = context.documents;
// Fields to tokenize
final String [] fieldNames = documentFields.toArray(new String [documentFields.size()]);
if (fieldNames.length > 8)
{
throw new ProcessingException("Maximum number of tokenized fields is 8.");
}
// Prepare arrays
images = Lists.newArrayList();
tokenTypes = new ShortArrayList();
documentIndices = new IntArrayList();
fieldIndices = new ByteArrayList();
final Iterator<Document> docIterator = documents.iterator();
int documentIndex = 0;
final ITokenizer ts = context.language.getTokenizer();
final MutableCharArray wrapper = new MutableCharArray(CharArrayUtils.EMPTY_ARRAY);
while (docIterator.hasNext())
{
final Document doc = docIterator.next();
boolean hadTokens = false;
for (int i = 0; i < fieldNames.length; i++)
{
final byte fieldIndex = (byte) i;
final String fieldName = fieldNames[i];
final String fieldValue = doc.getField(fieldName);
if (!StringUtils.isEmpty(fieldValue))
{
try
{
short tokenType;
ts.reset(new StringReader(fieldValue));
if ((tokenType = ts.nextToken()) != ITokenizer.TT_EOF)
{
if (hadTokens) addFieldSeparator(documentIndex);
do
{
ts.setTermBuffer(wrapper);
add(documentIndex, fieldIndex, context.intern(wrapper), tokenType);
} while ( (tokenType = ts.nextToken()) != ITokenizer.TT_EOF);
hadTokens = true;
}
}
catch (IOException e)
{
// Not possible (StringReader above)?
throw ExceptionUtils.wrapAsRuntimeException(e);
}
}
}
if (docIterator.hasNext())
{
addDocumentSeparator();
}
documentIndex++;
}
addTerminator();
// Save results in the PreprocessingContext
context.allTokens.documentIndex = documentIndices.toArray();
context.allTokens.fieldIndex = fieldIndices.toArray();
context.allTokens.image = images.toArray(new char [images.size()] []);
context.allTokens.type = tokenTypes.toArray();
context.allFields.name = fieldNames;
// Clean up
images = null;
fieldIndices = null;
tokenTypes = null;
documentIndices = null;
}
/**
* Adds a special terminating token required at the very end of all documents.
*/
void addTerminator()
{
add(-1, (byte) -1, null, ITokenizer.TF_TERMINATOR);
}
/**
* Adds a document separator to the lists.
*/
void addDocumentSeparator()
{
add(-1, (byte) -1, null, ITokenizer.TF_SEPARATOR_DOCUMENT);
}
/**
* Adds a field separator to the lists.
*/
void addFieldSeparator(int documentIndex)
{
add(documentIndex, (byte) -1, null, ITokenizer.TF_SEPARATOR_FIELD);
}
/**
* Adds a sentence separator to the lists.
*/
void addSentenceSeparator(int documentIndex, byte fieldIndex)
{
add(documentIndex, fieldIndex, null, ITokenizer.TF_SEPARATOR_FIELD);
}
/**
* Adds custom token code to the sequence. May be used to add separator constants.
*/
void add(int documentIndex, byte fieldIndex, char [] image, short tokenTypeCode)
{
documentIndices.add(documentIndex);
fieldIndices.add(fieldIndex);
images.add(image);
tokenTypes.add(tokenTypeCode);
}
}