Create a dictionary collection and a dictionary factory.

The dictionary collection is a class complying to the Dictionary
interface that acts as a front end to a collection of arbitrarily many
dictionaries of any type.
The dictionary factory is a helper class for creating various
dictionaries and get some meta information about them.

At the same time, this change makes the BinaryDictionary class
not a singleton any more.

This also needs I9afe61a9 to not break the build.

Change-Id: I61fdcc4867fcda18342807bf1865e6e46979e5d5

1 files changed, 159 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/DictionaryFactory.java b/java/src/com/android/inputmethod/latin/DictionaryFactory.java
new file mode 100644
index 000000000..cd42d7c3d
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/DictionaryFactory.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2011 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.inputmethod.latin;
+
+import android.content.Context;
+import android.content.res.AssetFileDescriptor;
+import android.content.res.Configuration;
+import android.content.res.Resources;
+import android.util.Log;
+
+import java.io.File;
+import java.util.Locale;
+
+/**
+ * Factory for dictionary instances.
+ */
+public class DictionaryFactory {
+
+    private static String TAG = DictionaryFactory.class.getSimpleName();
+
+    /**
+     * Initializes a dictionary from a dictionary pack.
+     *
+     * This searches for a content provider providing a dictionary pack for the specified
+     * locale. If none is found, it falls back to using the resource passed as fallBackResId
+     * as a dictionary.
+     * @param context application context for reading resources
+     * @param locale the locale for which to create the dictionary
+     * @param fallbackResId the id of the resource to use as a fallback if no pack is found
+     * @return an initialized instance of Dictionary
+     */
+    public static Dictionary createDictionaryFromManager(Context context, Locale locale,
+            int fallbackResId) {
+        if (null == locale) {
+            Log.e(TAG, "No locale defined for dictionary");
+            return new DictionaryCollection(createBinaryDictionary(context, fallbackResId));
+        }
+
+        final AssetFileAddress dictFile = BinaryDictionaryGetter.getDictionaryFile(locale,
+                context, fallbackResId);
+        if (null == dictFile) return null;
+        return new DictionaryCollection(new BinaryDictionary(context,
+                dictFile.mFilename, dictFile.mOffset, dictFile.mLength, null));
+    }
+
+    /**
+     * Initializes a dictionary from a raw resource file
+     * @param context application context for reading resources
+     * @param resId the resource containing the raw binary dictionary
+     * @return an initialized instance of BinaryDictionary
+     */
+    protected static BinaryDictionary createBinaryDictionary(Context context, int resId) {
+        AssetFileDescriptor afd = null;
+        try {
+            // TODO: IMPORTANT: Do not create a dictionary from a placeholder.
+            afd = context.getResources().openRawResourceFd(resId);
+            if (afd == null) {
+                Log.e(TAG, "Found the resource but it is compressed. resId=" + resId);
+                return null;
+            }
+            if (!isFullDictionary(afd)) return null;
+            final String sourceDir = context.getApplicationInfo().sourceDir;
+            final File packagePath = new File(sourceDir);
+            // TODO: Come up with a way to handle a directory.
+            if (!packagePath.isFile()) {
+                Log.e(TAG, "sourceDir is not a file: " + sourceDir);
+                return null;
+            }
+            return new BinaryDictionary(context,
+                    sourceDir, afd.getStartOffset(), afd.getLength(), null);
+        } catch (android.content.res.Resources.NotFoundException e) {
+            Log.e(TAG, "Could not find the resource. resId=" + resId);
+            return null;
+        } finally {
+            if (null != afd) {
+                try {
+                    afd.close();
+                } catch (java.io.IOException e) {
+                    /* IOException on close ? What am I supposed to do ? */
+                }
+            }
+        }
+    }
+
+    /**
+     * Create a dictionary from passed data. This is intended for unit tests only.
+     * @param context the test context to create this data from.
+     * @param dictionary the file to read
+     * @param startOffset the offset in the file where the data starts
+     * @param length the length of the data
+     * @param flagArray the flags to use with this data for testing
+     * @return the created dictionary, or null.
+     */
+    public static Dictionary createDictionaryForTest(Context context, File dictionary,
+            long startOffset, long length, Flag[] flagArray) {
+        if (dictionary.isFile()) {
+            return new BinaryDictionary(context, dictionary.getAbsolutePath(), startOffset, length,
+                    flagArray);
+        } else {
+            Log.e(TAG, "Could not find the file. path=" + dictionary.getAbsolutePath());
+            return null;
+        }
+    }
+
+    /**
+     * Find out whether a dictionary is available for this locale.
+     * @param context the context on which to check resources.
+     * @param locale the locale to check for.
+     * @return whether a (non-placeholder) dictionary is available or not.
+     */
+    public static boolean isDictionaryAvailable(Context context, Locale locale) {
+        final Resources res = context.getResources();
+        final Configuration conf = res.getConfiguration();
+        final Locale saveLocale = conf.locale;
+        conf.locale = locale;
+        res.updateConfiguration(conf, res.getDisplayMetrics());
+
+        final int resourceId = Utils.getMainDictionaryResourceId(res);
+        final AssetFileDescriptor afd = context.getResources().openRawResourceFd(resourceId);
+        final boolean hasDictionary = isFullDictionary(afd);
+        try {
+            if (null != afd) afd.close();
+        } catch (java.io.IOException e) {
+            /* Um, what can we do here exactly? */
+        }
+
+        conf.locale = saveLocale;
+        res.updateConfiguration(conf, res.getDisplayMetrics());
+        return hasDictionary;
+    }
+
+    // TODO: Find the Right Way to find out whether the resource is a placeholder or not.
+    // Suggestion : strip the locale, open the placeholder file and store its offset.
+    // Upon opening the file, if it's the same offset, then it's the placeholder.
+    private static final long PLACEHOLDER_LENGTH = 34;
+    /**
+     * Finds out whether the data pointed out by an AssetFileDescriptor is a full
+     * dictionary (as opposed to null, or to a place holder).
+     * @param afd the file descriptor to test, or null
+     * @return true if the dictionary is a real full dictionary, false if it's null or a placeholder
+     */
+    protected static boolean isFullDictionary(final AssetFileDescriptor afd) {
+        return (afd != null && afd.getLength() > PLACEHOLDER_LENGTH);
+    }
+}