hu.ppke.itk.nlpg.purepos.model.internal.HashSuffixTree.java Source code

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Here is the source code for hu.ppke.itk.nlpg.purepos.model.internal.HashSuffixTree.java

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/*******************************************************************************
 * Copyright (c) 2012 Gyrgy Orosz, Attila Novk.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser Public License v3
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/
 * 
 * This file is part of PurePos.
 * 
 * PurePos is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * PurePos is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser Public License for more details.
 * 
 * Contributors:
 *     Gyrgy Orosz - initial API and implementation
 ******************************************************************************/
package hu.ppke.itk.nlpg.purepos.model.internal;

import hu.ppke.itk.nlpg.purepos.model.ISuffixGuesser;
import hu.ppke.itk.nlpg.purepos.model.SuffixTree;

import java.util.HashMap;

import org.apache.commons.lang3.tuple.MutablePair;

/**
 * Suffix tree implementation, representing nodes in a hash table. Edges are not
 * stored, they can be easily constant time calculated from the strings.
 * 
 * @author Gyrgy Orosz
 * 
 * @param <T>
 *            Stored tags type
 */
public class HashSuffixTree<T> extends SuffixTree<String, T> {
    /**
     * 
     */
    private static final long serialVersionUID = 3763884096384725634L;
    /**
     * A node is: (suffix, ((tag, tag count), suffix count))
     */
    protected HashMap<String, MutablePair<HashMap<T, Integer>, Integer>> representation = new HashMap<String, MutablePair<HashMap<T, Integer>, Integer>>();
    protected Integer totalTagCount = 0;

    public HashSuffixTree(int maxSuffixLength) {
        super(maxSuffixLength);
    }

    @Override
    public void addWord(String word, T tag, int count) {
        int end = word.length();
        int start = Math.max(0, end - maxSuffixLength);
        for (int pointer = start; pointer <= end; pointer++) {
            String suffix = word.substring(pointer);
            increment(suffix, tag, count);
        }
        totalTagCount += count;
    }

    @Override
    public void addWord(String word, T tag, int count, int minLen) {
        int end = word.length() - minLen;
        int start = Math.max(0, end - maxSuffixLength);
        for (int pointer = start; pointer <= end; pointer++) {
            String suffix = word.substring(pointer);
            increment(suffix, tag, count);
        }
        totalTagCount += count;
    }

    protected void increment(String suffix, T tag, int count) {
        if (representation.containsKey(suffix)) {
            MutablePair<HashMap<T, Integer>, Integer> value = representation.get(suffix);
            HashMap<T, Integer> tagCounts = value.getLeft();
            if (tagCounts.containsKey(tag)) {
                tagCounts.put(tag, tagCounts.get(tag) + count);
            } else {
                tagCounts.put(tag, count);
            }
            value.setRight(value.getRight() + count);
        } else {
            HashMap<T, Integer> tagCounts = new HashMap<T, Integer>();
            tagCounts.put(tag, count);
            MutablePair<HashMap<T, Integer>, Integer> value = new MutablePair<HashMap<T, Integer>, Integer>(
                    tagCounts, count);
            representation.put(suffix, value);
        }
    }

    @Override
    public ISuffixGuesser<String, T> createGuesser(double theta
    // Map<T, Double> aprioriProbs
    ) {
        return new HashSuffixGuesser<T>(representation,
                // aprioriProbs,
                theta);
    }

}