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/ime/latinime/src/com/googlecode/eyesfree/inputmethod/latin/Dictionary.java

http://eyes-free.googlecode.com/
Java | 120 lines | 31 code | 10 blank | 79 comment | 5 complexity | bee8de72169e9d56f8ab5759c6bd23fc MD5 | raw file
  1/*
  2 * Copyright (C) 2008 The Android Open Source Project
  3 * 
  4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  5 * use this file except in compliance with the License. You may obtain a copy of
  6 * the License at
  7 * 
  8 * http://www.apache.org/licenses/LICENSE-2.0
  9 * 
 10 * Unless required by applicable law or agreed to in writing, software
 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 13 * License for the specific language governing permissions and limitations under
 14 * the License.
 15 */
 16
 17package com.googlecode.eyesfree.inputmethod.latin;
 18
 19/**
 20 * Abstract base class for a dictionary that can do a fuzzy search for words based on a set of key
 21 * strokes.
 22 */
 23abstract public class Dictionary {
 24    /**
 25     * Whether or not to replicate the typed word in the suggested list, even if it's valid.
 26     */
 27    protected static final boolean INCLUDE_TYPED_WORD_IF_VALID = false;
 28    
 29    /**
 30     * The weight to give to a word if it's length is the same as the number of typed characters.
 31     */
 32    protected static final int FULL_WORD_FREQ_MULTIPLIER = 2;
 33
 34    public static enum DataType {
 35        UNIGRAM, BIGRAM
 36    }
 37
 38    /**
 39     * Interface to be implemented by classes requesting words to be fetched from the dictionary.
 40     * @see #getWords(WordComposer, WordCallback, int[])
 41     */
 42    public interface WordCallback {
 43        /**
 44         * Adds a word to a list of suggestions. The word is expected to be ordered based on
 45         * the provided frequency. 
 46         * @param word the character array containing the word
 47         * @param wordOffset starting offset of the word in the character array
 48         * @param wordLength length of valid characters in the character array
 49         * @param frequency the frequency of occurence. This is normalized between 1 and 255, but
 50         * can exceed those limits
 51         * @param dicTypeId of the dictionary where word was from
 52         * @param dataType tells type of this data
 53         * @return true if the word was added, false if no more words are required
 54         */
 55        boolean addWord(char[] word, int wordOffset, int wordLength, int frequency, int dicTypeId,
 56                DataType dataType);
 57    }
 58
 59    /**
 60     * Searches for words in the dictionary that match the characters in the composer. Matched 
 61     * words are added through the callback object.
 62     * @param composer the key sequence to match
 63     * @param callback the callback object to send matched words to as possible candidates
 64     * @param nextLettersFrequencies array of frequencies of next letters that could follow the
 65     *        word so far. For instance, "bracke" can be followed by "t", so array['t'] will have
 66     *        a non-zero value on returning from this method. 
 67     *        Pass in null if you don't want the dictionary to look up next letters.
 68     * @see WordCallback#addWord(char[], int, int, int, int, DataType)
 69     */
 70    abstract public void getWords(final WordComposer composer, final WordCallback callback,
 71            int[] nextLettersFrequencies);
 72
 73    /**
 74     * Searches for pairs in the bigram dictionary that matches the previous word and all the
 75     * possible words following are added through the callback object.
 76     * @param composer the key sequence to match
 77     * @param callback the callback object to send possible word following previous word
 78     * @param nextLettersFrequencies array of frequencies of next letters that could follow the
 79     *        word so far. For instance, "bracke" can be followed by "t", so array['t'] will have
 80     *        a non-zero value on returning from this method.
 81     *        Pass in null if you don't want the dictionary to look up next letters.
 82     */
 83    public void getBigrams(final WordComposer composer, final CharSequence previousWord,
 84            final WordCallback callback, int[] nextLettersFrequencies) {
 85        // empty base implementation
 86    }
 87
 88    /**
 89     * Checks if the given word occurs in the dictionary
 90     * @param word the word to search for. The search should be case-insensitive.
 91     * @return true if the word exists, false otherwise
 92     */
 93    abstract public boolean isValidWord(CharSequence word);
 94    
 95    /**
 96     * Compares the contents of the character array with the typed word and returns true if they
 97     * are the same.
 98     * @param word the array of characters that make up the word
 99     * @param length the number of valid characters in the character array
100     * @param typedWord the word to compare with
101     * @return true if they are the same, false otherwise.
102     */
103    protected boolean same(final char[] word, final int length, final CharSequence typedWord) {
104        if (typedWord.length() != length) {
105            return false;
106        }
107        for (int i = 0; i < length; i++) {
108            if (word[i] != typedWord.charAt(i)) {
109                return false;
110            }
111        }
112        return true;
113    }
114
115    /**
116     * Override to clean up any resources.
117     */
118    public void close() {
119    }
120}