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/*
* Copyright (C) 2013 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.makedict;
import com.android.inputmethod.annotations.UsedForTesting;
import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.DictBuffer;
import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
import com.android.inputmethod.latin.utils.ByteArrayDictBuffer;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/**
* An interface of binary dictionary decoder.
*/
public interface DictDecoder {
public FileHeader readHeader() throws IOException, UnsupportedFormatException;
public interface DictionaryBufferFactory {
public DictBuffer getDictionaryBuffer(final File file)
throws FileNotFoundException, IOException;
}
/**
* Creates DictionaryBuffer using a ByteBuffer
*
* This class uses less memory than DictionaryBufferFromByteArrayFactory,
* but doesn't perform as fast.
* When operating on a big dictionary, this class is preferred.
*/
public static final class DictionaryBufferFromReadOnlyByteBufferFactory
implements DictionaryBufferFactory {
@Override
public DictBuffer getDictionaryBuffer(final File file)
throws FileNotFoundException, IOException {
FileInputStream inStream = null;
ByteBuffer buffer = null;
try {
inStream = new FileInputStream(file);
buffer = inStream.getChannel().map(FileChannel.MapMode.READ_ONLY,
0, file.length());
} finally {
if (inStream != null) {
inStream.close();
}
}
if (buffer != null) {
return new BinaryDictDecoderUtils.ByteBufferDictBuffer(buffer);
}
return null;
}
}
/**
* Creates DictionaryBuffer using a byte array
*
* This class performs faster than other classes, but consumes more memory.
* When operating on a small dictionary, this class is preferred.
*/
public static final class DictionaryBufferFromByteArrayFactory
implements DictionaryBufferFactory {
@Override
public DictBuffer getDictionaryBuffer(final File file)
throws FileNotFoundException, IOException {
FileInputStream inStream = null;
try {
inStream = new FileInputStream(file);
final byte[] array = new byte[(int) file.length()];
inStream.read(array);
return new ByteArrayDictBuffer(array);
} finally {
if (inStream != null) {
inStream.close();
}
}
}
}
/**
* Creates DictionaryBuffer using a writable ByteBuffer and a RandomAccessFile.
*
* This class doesn't perform as fast as other classes,
* but this class is the only option available for destructive operations (insert or delete)
* on a dictionary.
*/
@UsedForTesting
public static final class DictionaryBufferFromWritableByteBufferFactory
implements DictionaryBufferFactory {
@Override
public DictBuffer getDictionaryBuffer(final File file)
throws FileNotFoundException, IOException {
RandomAccessFile raFile = null;
ByteBuffer buffer = null;
try {
raFile = new RandomAccessFile(file, "rw");
buffer = raFile.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, file.length());
} finally {
if (raFile != null) {
raFile.close();
}
}
if (buffer != null) {
return new BinaryDictDecoderUtils.ByteBufferDictBuffer(buffer);
}
return null;
}
}
}
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