Trie.java

package org.maltparser.core.symbol.trie;

import org.maltparser.core.symbol.SymbolException;

/**
 *
 * @author Johan Hall
 * @since 1.0
*
 */
public class Trie {

    private final TrieNode root;
    private final StringBuilder sb;

    public Trie() {
        root = new TrieNode(' ', null);
        sb = new StringBuilder();
    }

    public TrieNode addValue(String value, TrieSymbolTable table, int code) throws SymbolException {
        TrieNode node = root;
        final char[] chars = value.toCharArray();
        for (int i = chars.length - 1; i >= 0; i--) {
            if (i == 0) {
                node = node.getOrAddChild(true, chars[i], table, code);
            } else {
                node = node.getOrAddChild(false, chars[i], table, code);
            }
        }
        return node;
    }

    public TrieNode addValue(StringBuilder symbol, TrieSymbolTable table, int code) throws SymbolException {
        TrieNode node = root;
        for (int i = symbol.length() - 1; i >= 0; i--) {
            if (i == 0) {
                node = node.getOrAddChild(true, symbol.charAt(i), table, code);
            } else {
                node = node.getOrAddChild(false, symbol.charAt(i), table, code);
            }
        }
        return node;
    }

    public String getValue(TrieNode node, TrieSymbolTable table) {
        sb.setLength(0);
        TrieNode tmp = node;
        while (tmp != root) { // && tmp != null) {
            sb.append(tmp.getCharacter());
            tmp = tmp.getParent();
        }
        return sb.toString();
    }

    public Integer getEntry(String value, TrieSymbolTable table) {
        TrieNode node = root;
        final char[] chars = value.toCharArray();
        int i = chars.length - 1;
        for (; i >= 0 && node != null; i--) {
            node = node.getChild(chars[i]);
        }
        if (i < 0 && node != null) {
            return node.getEntry(table);
        }
        return null;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        return ((root == null) ? ((Trie) obj).root == null : root.equals(((Trie) obj).root));
    }

    @Override
    public int hashCode() {
        return 31 * 7 + (null == root ? 0 : root.hashCode());
    }
}