Dictionary.java revision b8a9479b57007edb5cb12c628797f89a8164f596 
1/*
2 * Copyright (C) 2008 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
17package com.android.inputmethod.latin;
18
19import com.android.inputmethod.annotations.UsedForTesting;
20import com.android.inputmethod.keyboard.ProximityInfo;
21import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
22import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
23
24import java.util.ArrayList;
25
26/**
27 * Abstract base class for a dictionary that can do a fuzzy search for words based on a set of key
28 * strokes.
29 */
30public abstract class Dictionary {
31    public static final int NOT_A_PROBABILITY = -1;
32    public static final float NOT_A_LANGUAGE_WEIGHT = -1.0f;
33
34    // The following types do not actually come from real dictionary instances, so we create
35    // corresponding instances.
36    public static final String TYPE_USER_TYPED = "user_typed";
37    public static final Dictionary DICTIONARY_USER_TYPED = new PhonyDictionary(TYPE_USER_TYPED);
38
39    public static final String TYPE_APPLICATION_DEFINED = "application_defined";
40    public static final Dictionary DICTIONARY_APPLICATION_DEFINED =
41            new PhonyDictionary(TYPE_APPLICATION_DEFINED);
42
43    public static final String TYPE_HARDCODED = "hardcoded"; // punctuation signs and such
44    public static final Dictionary DICTIONARY_HARDCODED =
45            new PhonyDictionary(TYPE_HARDCODED);
46
47    // Spawned by resuming suggestions. Comes from a span that was in the TextView.
48    public static final String TYPE_RESUMED = "resumed";
49    public static final Dictionary DICTIONARY_RESUMED =
50            new PhonyDictionary(TYPE_RESUMED);
51
52    // The following types of dictionary have actual functional instances. We don't need final
53    // phony dictionary instances for them.
54    public static final String TYPE_MAIN = "main";
55    public static final String TYPE_CONTACTS = "contacts";
56    // User dictionary, the system-managed one.
57    public static final String TYPE_USER = "user";
58    // User history dictionary internal to LatinIME.
59    public static final String TYPE_USER_HISTORY = "history";
60    // Personalization dictionary.
61    public static final String TYPE_PERSONALIZATION = "personalization";
62    // Contextual dictionary.
63    public static final String TYPE_CONTEXTUAL = "contextual";
64    public final String mDictType;
65
66    public Dictionary(final String dictType) {
67        mDictType = dictType;
68    }
69
70    /**
71     * Searches for suggestions for a given context. For the moment the context is only the
72     * previous word.
73     * @param composer the key sequence to match with coordinate info, as a WordComposer
74     * @param prevWordsInfo the information of previous words.
75     * @param proximityInfo the object for key proximity. May be ignored by some implementations.
76     * @param settingsValuesForSuggestion the settings values used for the suggestion.
77     * @param sessionId the session id.
78     * @param inOutLanguageWeight the language weight used for generating suggestions.
79     * inOutLanguageWeight is a float array that has only one element. This can be updated when the
80     * different language weight is used.
81     * @return the list of suggestions (possibly null if none)
82     */
83    abstract public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
84            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
85            final SettingsValuesForSuggestion settingsValuesForSuggestion,
86            final int sessionId, final float[] inOutLanguageWeight);
87
88    /**
89     * Checks if the given word has to be treated as a valid word. Please note that some
90     * dictionaries have entries that should be treated as invalid words.
91     * @param word the word to search for. The search should be case-insensitive.
92     * @return true if the word is valid, false otherwise
93     */
94    public boolean isValidWord(final String word) {
95        return isInDictionary(word);
96    }
97
98    /**
99     * Checks if the given word is in the dictionary regardless of it being valid or not.
100     */
101    abstract public boolean isInDictionary(final String word);
102
103    public int getFrequency(final String word) {
104        return NOT_A_PROBABILITY;
105    }
106
107    public int getMaxFrequencyOfExactMatches(final String word) {
108        return NOT_A_PROBABILITY;
109    }
110
111    /**
112     * Compares the contents of the character array with the typed word and returns true if they
113     * are the same.
114     * @param word the array of characters that make up the word
115     * @param length the number of valid characters in the character array
116     * @param typedWord the word to compare with
117     * @return true if they are the same, false otherwise.
118     */
119    protected boolean same(final char[] word, final int length, final String typedWord) {
120        if (typedWord.length() != length) {
121            return false;
122        }
123        for (int i = 0; i < length; i++) {
124            if (word[i] != typedWord.charAt(i)) {
125                return false;
126            }
127        }
128        return true;
129    }
130
131    /**
132     * Override to clean up any resources.
133     */
134    public void close() {
135        // empty base implementation
136    }
137
138    /**
139     * Subclasses may override to indicate that this Dictionary is not yet properly initialized.
140     */
141    public boolean isInitialized() {
142        return true;
143    }
144
145    /**
146     * Whether we think this suggestion should trigger an auto-commit. prevWord is the word
147     * before the suggestion, so that we can use n-gram frequencies.
148     * @param candidate The candidate suggestion, in whole (not only the first part).
149     * @return whether we should auto-commit or not.
150     */
151    public boolean shouldAutoCommit(final SuggestedWordInfo candidate) {
152        // If we don't have support for auto-commit, or if we don't know, we return false to
153        // avoid auto-committing stuff. Implementations of the Dictionary class that know to
154        // determine whether we should auto-commit will override this.
155        return false;
156    }
157
158    /**
159     * Not a true dictionary. A placeholder used to indicate suggestions that don't come from any
160     * real dictionary.
161     */
162    private static class PhonyDictionary extends Dictionary {
163        // This class is not publicly instantiable.
164        private PhonyDictionary(final String type) {
165            super(type);
166        }
167
168        @Override
169        public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
170                final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
171                final SettingsValuesForSuggestion settingsValuesForSuggestion,
172                final int sessionId, final float[] inOutLanguageWeight) {
173            return null;
174        }
175
176        @Override
177        public boolean isInDictionary(String word) {
178            return false;
179        }
180    }
181}
182