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an Open Source BPMN 2.0 Modeler
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/*
 *  JOrtho
 *
 *  Copyright (C) 2005-2008 by i-net software
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version. 
 *
 *  This program 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
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 *  
 *  Created on 02.11.2005
 */
package com.inet.jortho;

import java.util.*;

/**
 * @author Volker Berlin
 */
abstract class DictionaryBase {

    protected char[] tree;
    protected int size;
    protected int idx;
    
    
    protected static final char LAST_CHAR = 0xFFFF;
    
    
    DictionaryBase(char[] tree){
        this.tree = tree;
        size = tree.length;
    }
    
    /**
     * Empty Constructor.
     */
    protected DictionaryBase(){
        /* empty */
    }
    
    
    /**
     * Check if the word exist in this dictinary.
     * @param word the word to check. Can't be null.
     * @return true if the word exist.
     */
    public boolean exist(String word){
        idx = 0;
        for(int i=0; i=size || tree[idx] != c)){
                return false;
            }
            if( i == word.length() - 1 && isWordMatch() ) {
                return true;
            }
            idx = readIndex();
            if(idx <= 0) return false;
        }
        return false;
    }
    
    
    
    /**
     * Returns a list of suggestions if the word is not in the dictionary.
     * @param word the wrong spelled word. Can't be null.
     * @return a list of class Suggestion.
     * @see Suggestion
     */
    public List searchSuggestions(String word){
        if(word.length() == 0 || exist(word)){
            return new ArrayList();
        }
        Suggestions suggesions = new Suggestions( Math.min( 20, 4+word.length() ) );
        idx = 0;
        searchSuggestions( suggesions, word, 0, 0, 0);
        List list = suggesions.getlist();
        Collections.sort( list );
        return list;
    }
    
    
    /**
     * It will search with different rules for similar words.
     * For every rule there are a different difference. The smaller the difference that so similarer.
     * This method is calling recursive it self.
     * @param list Container for found words
     * @param chars until charPosition already map characters, after the part of the original word that still need to map.
     * @param charPosition character position in char array
     * @param lastIdx position in the index (dictionary) to the current character position
     * @param diff the dissimilar up to the current character position
     */
    private void searchSuggestions( Suggestions list, CharSequence chars, int charPosition, int lastIdx, int diff){
        if(diff > list.getMaxDissimilarity()){
            return;
        }
        // First with the correct letters to go on 
        idx = lastIdx;
        char currentChar = chars.charAt(charPosition);
        if(searchChar(currentChar)){
            if( isWordMatch() ) {
                if(charPosition+1 == chars.length()){
                    // exact match at this character position
                    list.add( new Suggestion(chars, diff));
                }else{
                    // a shorter match, we need to cut the string
                    int length = charPosition+1;
                    CharSequence chars2 = chars.subSequence( 0, length );
                    list.add( new Suggestion(chars2, diff + (chars.length()-length)*5));
                }
            }
            idx = readIndex();
            if( idx > 0 ) {
                // more characters in the tree
                if(charPosition+1 == chars.length()){
                    searchSuggestionsLonger( list, chars, idx, diff + 5);
                } else {
                    searchSuggestions( list, chars, charPosition + 1, idx, diff );
                }
            }
        }

        
        // transposed letters and additional letter
        if(charPosition+1 < chars.length()){
            idx = lastIdx;
            currentChar = chars.charAt(charPosition+1);
            if(searchChar(currentChar)){
                int tempIdx = idx;
                
                //transposed letters (German - Buchstabendreher)
                idx = readIndex();
                if( idx > 0 ) {
                    StringBuilder buffer = new StringBuilder( chars );
                    buffer.setCharAt( charPosition+1, chars.charAt( charPosition ) );
                    buffer.setCharAt( charPosition, currentChar );
                    searchSuggestions( list, buffer, charPosition+1, idx, diff+3);
                }
                
                // Additional character in the misspelled word
                idx = tempIdx;
                StringBuilder buffer = new StringBuilder();
                buffer.append( chars, 0, charPosition );
                buffer.append( chars, charPosition+1, chars.length() );
                searchSuggestions( list, buffer, charPosition, lastIdx, diff+5);
            }
        }

        // Missing letters, we need to add one character
        {
            int tempIdx = idx = lastIdx;
            while( idx < size && tree[idx] < LAST_CHAR ) {
                char newChar = tree[idx];
                idx = readIndex();
                if( idx > 0 && newChar != currentChar) {
                    StringBuilder buffer = new StringBuilder( chars );
                    buffer.insert( charPosition, newChar );
                    searchSuggestions( list, buffer, charPosition + 1, idx, diff + 5 );
                }
                idx = tempIdx += 3;
            }
        }
        
        // Typos - wrong letters (One character is replaced with any character)
        if(charPosition < chars.length()){
            currentChar = chars.charAt(charPosition);
            int tempIdx = idx = lastIdx;
            while( idx < size && tree[idx] < LAST_CHAR ) {
                if( isWordMatch() ){
                    StringBuilder buffer = new StringBuilder();
                    buffer.append( chars, 0, charPosition );
                    buffer.append( tree[idx] );
                    list.add( new Suggestion( buffer, diff + 5 + (chars.length()-buffer.length())*5 ) );
                }
                if(charPosition + 1 < chars.length()){
                    char newChar = tree[idx];
                    idx = readIndex();
                    if( idx > 0 && newChar != currentChar) {
                        StringBuilder buffer = new StringBuilder( chars );
                        buffer.setCharAt( charPosition, newChar );
                        searchSuggestions( list, buffer, charPosition + 1, idx, diff + charDiff( currentChar, newChar ) );
                    }
                }
                idx = tempIdx += 3;
            }
        }
    }
    
    private void searchSuggestionsLonger( Suggestions list, CharSequence chars, int lastIdx, int diff){
        int tempIdx = idx = lastIdx;
        while(idxidx point to the location.
     * If not found then it point on the next character (char value) item in the node. 
     * @param c the searching character
     * @return true if found
     */
    private boolean searchChar(char c){
        while(idx=size || tree[idx] != c)){
            return false;
        }
        return true;
    }
    
    /**
     * Check if on the current item position a word ends.
     */
    private boolean isWordMatch(){
        return (tree[idx + 1] & 0x8000) > 0;
    }
    
    /**
     * Read the offset in the tree of the next character. 
     */
    final int readIndex(){
        return ((tree[idx+1] & 0x7fff)<<16) + tree[idx+2]; 
    }
    
    /**
     * Returns an int that describe the dissimilarity of the characters. 
     * The value is ever larger 0. A value of means only a small difference.
     * @param a first char
     * @param b second char
     * @return the dissimilarity
     */
    private int charDiff( char a, char b ) {
        a = Character.toLowerCase( a );
        b = Character.toLowerCase( b );

        if( a == b ) {
            return 1;
        }

        if( Character.getType( a ) != Character.getType( b ) ) {
            return 6;
        }

        return 5;
    }
}