Load only unique dictionary words

- Move UserDictionarySettings to sub package
- Convert cursor to loader

Fix: 22058788
Test: robotests

Change-Id: I1e8828abee58362b815abc210c044b678bf9d578

src/com/android/settings/inputmethod/UserDictionaryCursorLoader.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.inputmethod;
+
+import android.content.Context;
+import android.content.CursorLoader;
+import android.database.Cursor;
+import android.database.MatrixCursor;
+import android.provider.UserDictionary;
+import android.support.annotation.VisibleForTesting;
+import android.util.ArraySet;
+
+import java.util.Locale;
+import java.util.Objects;
+import java.util.Set;
+
+public class UserDictionaryCursorLoader extends CursorLoader {
+
+    @VisibleForTesting
+    static final String[] QUERY_PROJECTION = {
+            UserDictionary.Words._ID,
+            UserDictionary.Words.WORD,
+            UserDictionary.Words.SHORTCUT
+    };
+
+    // The index of the shortcut in the above array.
+    static final int INDEX_SHORTCUT = 2;
+
+    // Either the locale is empty (means the word is applicable to all locales)
+    // or the word equals our current locale
+    private static final String QUERY_SELECTION =
+            UserDictionary.Words.LOCALE + "=?";
+    private static final String QUERY_SELECTION_ALL_LOCALES =
+            UserDictionary.Words.LOCALE + " is null";
+
+
+    // Locale can be any of:
+    // - The string representation of a locale, as returned by Locale#toString()
+    // - The empty string. This means we want a cursor returning words valid for all locales.
+    // - null. This means we want a cursor for the current locale, whatever this is.
+    // Note that this contrasts with the data inside the database, where NULL means "all
+    // locales" and there should never be an empty string. The confusion is called by the
+    // historical use of null for "all locales".
+    // TODO: it should be easy to make this more readable by making the special values
+    // human-readable, like "all_locales" and "current_locales" strings, provided they
+    // can be guaranteed not to match locales that may exist.
+    private final String mLocale;
+
+    public UserDictionaryCursorLoader(Context context, String locale) {
+        super(context);
+        mLocale = locale;
+    }
+
+    @Override
+    public Cursor loadInBackground() {
+        final MatrixCursor result = new MatrixCursor(QUERY_PROJECTION);
+        final Cursor candidate;
+        if ("".equals(mLocale)) {
+            // Case-insensitive sort
+            candidate = getContext().getContentResolver().query(
+                    UserDictionary.Words.CONTENT_URI, QUERY_PROJECTION,
+                    QUERY_SELECTION_ALL_LOCALES, null,
+                    "UPPER(" + UserDictionary.Words.WORD + ")");
+        } else {
+            final String queryLocale = null != mLocale ? mLocale : Locale.getDefault().toString();
+            candidate = getContext().getContentResolver().query(UserDictionary.Words.CONTENT_URI,
+                    QUERY_PROJECTION, QUERY_SELECTION,
+                    new String[]{queryLocale}, "UPPER(" + UserDictionary.Words.WORD + ")");
+        }
+        final Set<Integer> hashSet = new ArraySet<>();
+        for (candidate.moveToFirst(); !candidate.isAfterLast(); candidate.moveToNext()) {
+            final int id = candidate.getInt(0);
+            final String word = candidate.getString(1);
+            final String shortcut = candidate.getString(2);
+            final int hash = Objects.hash(word, shortcut);
+            if (hashSet.contains(hash)) {
+                continue;
+            }
+            hashSet.add(hash);
+            result.addRow(new Object[]{id, word, shortcut});
+        }
+        return result;
+    }
+}