[3952] | 1 | package com.swabunga.spell.engine;
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| 2 |
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| 3 | import java.io.*;
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| 4 | import java.util.*;
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| 5 |
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| 6 | /**
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| 7 | * Another implementation of <code>SpellDictionary</code> that doesn't cache any words in memory. Avoids the huge
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| 8 | * footprint of <code>SpellDictionaryHashMap</code> at the cost of relatively minor latency. A future version
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| 9 | * of this class that implements some caching strategies might be a good idea in the future, if there's any
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| 10 | * demand for it.
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| 11 | *
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| 12 | * This implementation requires a special dictionary file, with "code*word" lines sorted by code.
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| 13 | * It's using a dichotomy algorithm to search for words in the dictionary
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| 14 | *
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| 15 | * @author Damien Guillaume
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| 16 | * @version 0.1
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| 17 | */
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| 18 | public class SpellDictionaryDichoDisk extends SpellDictionaryASpell {
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| 19 |
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| 20 | /** Holds the dictionary file for reading*/
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| 21 | private RandomAccessFile dictFile = null;
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| 22 |
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| 23 | /** dictionary and phonetic file encoding */
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| 24 | private String encoding = null;
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| 25 |
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| 26 | /**
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| 27 | * Dictionary Convienence Constructor.
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| 28 | */
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| 29 | public SpellDictionaryDichoDisk(File wordList)
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| 30 | throws FileNotFoundException, IOException {
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| 31 | super((File) null);
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| 32 | dictFile = new RandomAccessFile(wordList, "r");
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| 33 | }
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| 34 |
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| 35 | /**
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| 36 | * Dictionary Convienence Constructor.
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| 37 | */
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| 38 | public SpellDictionaryDichoDisk(File wordList, String encoding)
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| 39 | throws FileNotFoundException, IOException {
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| 40 | super((File) null);
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| 41 | this.encoding = encoding;
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| 42 | dictFile = new RandomAccessFile(wordList, "r");
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| 43 | }
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| 44 |
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| 45 | /**
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| 46 | * Dictionary constructor that uses an aspell phonetic file to
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| 47 | * build the transformation table.
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| 48 | */
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| 49 | public SpellDictionaryDichoDisk(File wordList, File phonetic)
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| 50 | throws FileNotFoundException, IOException {
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| 51 | super(phonetic);
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| 52 | dictFile = new RandomAccessFile(wordList, "r");
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| 53 | }
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| 54 |
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| 55 | /**
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| 56 | * Dictionary constructor that uses an aspell phonetic file to
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| 57 | * build the transformation table.
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| 58 | */
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| 59 | public SpellDictionaryDichoDisk(File wordList, File phonetic, String encoding)
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| 60 | throws FileNotFoundException, IOException {
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| 61 | super(phonetic, encoding);
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| 62 | this.encoding = encoding;
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| 63 | dictFile = new RandomAccessFile(wordList, "r");
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| 64 | }
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| 65 |
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| 66 | /**
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| 67 | * Add a word permanantly to the dictionary (and the dictionary file).
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| 68 | * <i>not implemented !</i>
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| 69 | */
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| 70 | public void addWord(String word) {
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| 71 | System.err.println("error: addWord is not implemented for SpellDictionaryDichoDisk");
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| 72 | }
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| 73 |
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| 74 | /**
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| 75 | * Search the dictionary file for the words corresponding to the code
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| 76 | * within positions p1 - p2
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| 77 | */
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| 78 | private LinkedList dichoFind(String code, long p1, long p2) throws IOException {
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| 79 | //System.out.println("dichoFind("+code+","+p1+","+p2+")");
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| 80 | long pm = (p1 + p2) / 2;
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| 81 | dictFile.seek(pm);
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| 82 | String l;
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| 83 | if (encoding == null)
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| 84 | l = dictFile.readLine();
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| 85 | else
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| 86 | l = dictReadLine();
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| 87 | pm = dictFile.getFilePointer();
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| 88 | if (encoding == null)
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| 89 | l = dictFile.readLine();
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| 90 | else
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| 91 | l = dictReadLine();
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| 92 | long pm2 = dictFile.getFilePointer();
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| 93 | if (pm2 >= p2)
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| 94 | return(seqFind(code, p1, p2));
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| 95 | int istar = l.indexOf('*');
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| 96 | if (istar == -1)
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| 97 | throw new IOException("bad format: no * !");
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| 98 | String testcode = l.substring(0, istar);
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| 99 | int comp = code.compareTo(testcode);
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| 100 | if (comp < 0)
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| 101 | return(dichoFind(code, p1, pm-1));
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| 102 | else if (comp > 0)
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| 103 | return(dichoFind(code, pm2, p2));
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| 104 | else {
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| 105 | LinkedList l1 = dichoFind(code, p1, pm-1);
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| 106 | LinkedList l2 = dichoFind(code, pm2, p2);
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| 107 | String word = l.substring(istar+1);
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| 108 | l1.add(word);
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| 109 | l1.addAll(l2);
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| 110 | return(l1);
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| 111 | }
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| 112 | }
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| 113 |
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| 114 | private LinkedList seqFind(String code, long p1, long p2) throws IOException {
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| 115 | //System.out.println("seqFind("+code+","+p1+","+p2+")");
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| 116 | LinkedList list = new LinkedList();
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| 117 | dictFile.seek(p1);
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| 118 | while (dictFile.getFilePointer() < p2) {
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| 119 | String l;
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| 120 | if (encoding == null)
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| 121 | l = dictFile.readLine();
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| 122 | else
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| 123 | l = dictReadLine();
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| 124 | int istar = l.indexOf('*');
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| 125 | if (istar == -1)
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| 126 | throw new IOException("bad format: no * !");
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| 127 | String testcode = l.substring(0, istar);
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| 128 | if (testcode.equals(code)) {
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| 129 | String word = l.substring(istar+1);
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| 130 | list.add(word);
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| 131 | }
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| 132 | }
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| 133 | return(list);
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| 134 | }
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| 135 |
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| 136 | /**
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| 137 | * Read a line of dictFile with a specific encoding
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| 138 | */
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| 139 | private String dictReadLine() throws IOException {
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| 140 | int max = 255;
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| 141 | byte b=0;
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| 142 | byte[] buf = new byte[max];
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| 143 | int i=0;
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| 144 | try {
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| 145 | for (; b != '\n' && b != '\r' && i<max-1; i++) {
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| 146 | b = dictFile.readByte();
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| 147 | buf[i] = b;
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| 148 | }
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| 149 | } catch (EOFException ex) {
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| 150 | }
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| 151 | if (i == 0)
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| 152 | return("");
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| 153 | String s = new String(buf, 0, i-1, encoding);
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| 154 | return(s);
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| 155 | }
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| 156 |
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| 157 | /**
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| 158 | * Returns a list of strings (words) for the code.
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| 159 | */
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| 160 | public List getWords(String code) {
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| 161 | //System.out.println("getWords("+code+")");
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| 162 | LinkedList list;
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| 163 | try {
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| 164 | list = dichoFind(code, 0, dictFile.length()-1);
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| 165 | //System.out.println(list);
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| 166 | } catch (IOException ex) {
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| 167 | System.err.println("IOException: " + ex.getMessage());
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| 168 | list = new LinkedList();
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| 169 | }
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| 170 | return list;
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| 171 | }
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| 172 |
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| 173 | }
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