The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2007 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of 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, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.text; |
| 18 | |
| 19 | import android.content.res.Resources; |
| 20 | import android.content.res.XmlResourceParser; |
Dianne Hackborn | 2269d157 | 2010-02-24 19:54:22 -0800 | [diff] [blame] | 21 | |
| 22 | import com.android.internal.util.XmlUtils; |
| 23 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 24 | import android.view.View; |
| 25 | |
| 26 | import org.xmlpull.v1.XmlPullParser; |
| 27 | import org.xmlpull.v1.XmlPullParserException; |
| 28 | |
| 29 | import java.io.IOException; |
| 30 | import java.util.Locale; |
| 31 | |
| 32 | /** |
| 33 | * This class accesses a dictionary of corrections to frequent misspellings. |
| 34 | */ |
| 35 | public class AutoText { |
| 36 | // struct trie { |
| 37 | // char c; |
| 38 | // int off; |
| 39 | // struct trie *child; |
| 40 | // struct trie *next; |
| 41 | // }; |
| 42 | |
| 43 | private static final int TRIE_C = 0; |
| 44 | private static final int TRIE_OFF = 1; |
| 45 | private static final int TRIE_CHILD = 2; |
| 46 | private static final int TRIE_NEXT = 3; |
| 47 | |
| 48 | private static final int TRIE_SIZEOF = 4; |
| 49 | private static final char TRIE_NULL = (char) -1; |
| 50 | private static final int TRIE_ROOT = 0; |
| 51 | |
| 52 | private static final int INCREMENT = 1024; |
| 53 | |
| 54 | private static final int DEFAULT = 14337; // Size of the Trie 13 Aug 2007 |
| 55 | |
| 56 | private static final int RIGHT = 9300; // Size of 'right' 13 Aug 2007 |
| 57 | |
| 58 | private static AutoText sInstance = new AutoText(Resources.getSystem()); |
| 59 | private static Object sLock = new Object(); |
| 60 | |
| 61 | // TODO: |
| 62 | // |
| 63 | // Note the assumption that the destination strings total less than |
| 64 | // 64K characters and that the trie for the source side totals less |
| 65 | // than 64K chars/offsets/child pointers/next pointers. |
| 66 | // |
| 67 | // This seems very safe for English (currently 7K of destination, |
| 68 | // 14K of trie) but may need to be revisited. |
| 69 | |
| 70 | private char[] mTrie; |
| 71 | private char mTrieUsed; |
| 72 | private String mText; |
| 73 | private Locale mLocale; |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 74 | private int mSize; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 75 | |
| 76 | private AutoText(Resources resources) { |
| 77 | mLocale = resources.getConfiguration().locale; |
| 78 | init(resources); |
| 79 | } |
| 80 | |
| 81 | /** |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 82 | * Returns the instance of AutoText. If the locale has changed, it will create a new |
| 83 | * instance of AutoText for the locale. |
| 84 | * @param view to get the resources from |
| 85 | * @return the single instance of AutoText |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 86 | */ |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 87 | private static AutoText getInstance(View view) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 88 | Resources res = view.getContext().getResources(); |
| 89 | Locale locale = res.getConfiguration().locale; |
| 90 | AutoText instance; |
| 91 | |
| 92 | synchronized (sLock) { |
| 93 | instance = sInstance; |
| 94 | |
| 95 | if (!locale.equals(instance.mLocale)) { |
| 96 | instance = new AutoText(res); |
| 97 | sInstance = instance; |
| 98 | } |
| 99 | } |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 100 | |
| 101 | return instance; |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Retrieves a possible spelling correction for the specified range |
| 106 | * of text. Returns null if no correction can be found. |
| 107 | * The View is used to get the current Locale and Resources. |
| 108 | */ |
| 109 | public static String get(CharSequence src, final int start, final int end, |
| 110 | View view) { |
| 111 | return getInstance(view).lookup(src, start, end); |
| 112 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 113 | |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 114 | /** |
| 115 | * Returns the size of the auto text dictionary. The return value can be zero if there is |
| 116 | * no auto correction data available for the current locale. |
| 117 | * @param view used to retrieve the current Locale and Resources. |
| 118 | * @return the number of entries in the auto text dictionary |
| 119 | */ |
| 120 | public static int getSize(View view) { |
| 121 | |
| 122 | return getInstance(view).getSize(); |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Returns the size of the dictionary. |
| 127 | */ |
| 128 | private int getSize() { |
| 129 | return mSize; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 130 | } |
| 131 | |
| 132 | private String lookup(CharSequence src, final int start, final int end) { |
| 133 | int here = mTrie[TRIE_ROOT]; |
| 134 | |
| 135 | for (int i = start; i < end; i++) { |
| 136 | char c = src.charAt(i); |
| 137 | |
| 138 | for (; here != TRIE_NULL; here = mTrie[here + TRIE_NEXT]) { |
| 139 | if (c == mTrie[here + TRIE_C]) { |
| 140 | if ((i == end - 1) |
| 141 | && (mTrie[here + TRIE_OFF] != TRIE_NULL)) { |
| 142 | int off = mTrie[here + TRIE_OFF]; |
| 143 | int len = mText.charAt(off); |
| 144 | |
| 145 | return mText.substring(off + 1, off + 1 + len); |
| 146 | } |
| 147 | |
| 148 | here = mTrie[here + TRIE_CHILD]; |
| 149 | break; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | if (here == TRIE_NULL) { |
| 154 | return null; |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | return null; |
| 159 | } |
| 160 | |
| 161 | private void init(Resources r) { |
| 162 | XmlResourceParser parser = r.getXml(com.android.internal.R.xml.autotext); |
| 163 | |
| 164 | StringBuilder right = new StringBuilder(RIGHT); |
| 165 | mTrie = new char[DEFAULT]; |
| 166 | mTrie[TRIE_ROOT] = TRIE_NULL; |
| 167 | mTrieUsed = TRIE_ROOT + 1; |
| 168 | |
| 169 | try { |
| 170 | XmlUtils.beginDocument(parser, "words"); |
| 171 | String odest = ""; |
| 172 | char ooff = 0; |
| 173 | |
| 174 | while (true) { |
| 175 | XmlUtils.nextElement(parser); |
| 176 | |
| 177 | String element = parser.getName(); |
| 178 | if (element == null || !(element.equals("word"))) { |
| 179 | break; |
| 180 | } |
| 181 | |
| 182 | String src = parser.getAttributeValue(null, "src"); |
| 183 | if (parser.next() == XmlPullParser.TEXT) { |
| 184 | String dest = parser.getText(); |
| 185 | char off; |
| 186 | |
| 187 | if (dest.equals(odest)) { |
| 188 | off = ooff; |
| 189 | } else { |
| 190 | off = (char) right.length(); |
| 191 | right.append((char) dest.length()); |
| 192 | right.append(dest); |
| 193 | } |
| 194 | |
| 195 | add(src, off); |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | // Don't let Resources cache a copy of all these strings. |
| 200 | r.flushLayoutCache(); |
| 201 | } catch (XmlPullParserException e) { |
| 202 | throw new RuntimeException(e); |
| 203 | } catch (IOException e) { |
| 204 | throw new RuntimeException(e); |
| 205 | } finally { |
| 206 | parser.close(); |
| 207 | } |
| 208 | |
| 209 | mText = right.toString(); |
| 210 | } |
| 211 | |
| 212 | private void add(String src, char off) { |
| 213 | int slen = src.length(); |
| 214 | int herep = TRIE_ROOT; |
Amith Yamasani | a565e5e | 2009-03-26 10:19:09 -0700 | [diff] [blame] | 215 | // Keep track of the size of the dictionary |
| 216 | mSize++; |
| 217 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 218 | for (int i = 0; i < slen; i++) { |
| 219 | char c = src.charAt(i); |
| 220 | boolean found = false; |
| 221 | |
| 222 | for (; mTrie[herep] != TRIE_NULL; |
| 223 | herep = mTrie[herep] + TRIE_NEXT) { |
| 224 | if (c == mTrie[mTrie[herep] + TRIE_C]) { |
| 225 | // There is a node for this letter, and this is the |
| 226 | // end, so fill in the right hand side fields. |
| 227 | |
| 228 | if (i == slen - 1) { |
| 229 | mTrie[mTrie[herep] + TRIE_OFF] = off; |
| 230 | return; |
| 231 | } |
| 232 | |
| 233 | // There is a node for this letter, and we need |
| 234 | // to go deeper into it to fill in the rest. |
| 235 | |
| 236 | herep = mTrie[herep] + TRIE_CHILD; |
| 237 | found = true; |
| 238 | break; |
| 239 | } |
| 240 | } |
| 241 | |
| 242 | if (!found) { |
| 243 | // No node for this letter yet. Make one. |
| 244 | |
| 245 | char node = newTrieNode(); |
| 246 | mTrie[herep] = node; |
| 247 | |
| 248 | mTrie[mTrie[herep] + TRIE_C] = c; |
| 249 | mTrie[mTrie[herep] + TRIE_OFF] = TRIE_NULL; |
| 250 | mTrie[mTrie[herep] + TRIE_NEXT] = TRIE_NULL; |
| 251 | mTrie[mTrie[herep] + TRIE_CHILD] = TRIE_NULL; |
| 252 | |
| 253 | // If this is the end of the word, fill in the offset. |
| 254 | |
| 255 | if (i == slen - 1) { |
| 256 | mTrie[mTrie[herep] + TRIE_OFF] = off; |
| 257 | return; |
| 258 | } |
| 259 | |
| 260 | // Otherwise, step in deeper and go to the next letter. |
| 261 | |
| 262 | herep = mTrie[herep] + TRIE_CHILD; |
| 263 | } |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | private char newTrieNode() { |
| 268 | if (mTrieUsed + TRIE_SIZEOF > mTrie.length) { |
| 269 | char[] copy = new char[mTrie.length + INCREMENT]; |
| 270 | System.arraycopy(mTrie, 0, copy, 0, mTrie.length); |
| 271 | mTrie = copy; |
| 272 | } |
| 273 | |
| 274 | char ret = mTrieUsed; |
| 275 | mTrieUsed += TRIE_SIZEOF; |
| 276 | |
| 277 | return ret; |
| 278 | } |
| 279 | } |