427 lines
16 KiB
Java
427 lines
16 KiB
Java
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.inputmethod.latin.makedict;
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import com.android.inputmethod.annotations.UsedForTesting;
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import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
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import java.io.File;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.nio.ByteBuffer;
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import java.util.HashMap;
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import java.util.LinkedList;
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import javax.annotation.Nonnull;
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/**
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* Decodes binary files for a FusionDictionary.
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*
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* All the methods in this class are static.
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*
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* TODO: Move this file to makedict/internal.
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* TODO: Rename this class to DictDecoderUtils.
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*/
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public final class BinaryDictDecoderUtils {
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private BinaryDictDecoderUtils() {
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// This utility class is not publicly instantiable.
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}
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@UsedForTesting
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public interface DictBuffer {
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public int readUnsignedByte();
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public int readUnsignedShort();
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public int readUnsignedInt24();
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public int readInt();
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public int position();
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public void position(int newPosition);
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@UsedForTesting
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public void put(final byte b);
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public int limit();
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@UsedForTesting
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public int capacity();
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}
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public static final class ByteBufferDictBuffer implements DictBuffer {
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private ByteBuffer mBuffer;
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public ByteBufferDictBuffer(final ByteBuffer buffer) {
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mBuffer = buffer;
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}
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@Override
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public int readUnsignedByte() {
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return mBuffer.get() & 0xFF;
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}
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@Override
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public int readUnsignedShort() {
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return mBuffer.getShort() & 0xFFFF;
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}
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@Override
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public int readUnsignedInt24() {
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final int retval = readUnsignedByte();
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return (retval << 16) + readUnsignedShort();
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}
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@Override
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public int readInt() {
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return mBuffer.getInt();
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}
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@Override
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public int position() {
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return mBuffer.position();
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}
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@Override
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public void position(int newPos) {
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mBuffer.position(newPos);
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}
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@Override
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public void put(final byte b) {
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mBuffer.put(b);
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}
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@Override
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public int limit() {
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return mBuffer.limit();
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}
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@Override
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public int capacity() {
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return mBuffer.capacity();
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}
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}
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/**
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* A class grouping utility function for our specific character encoding.
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*/
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static final class CharEncoding {
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/**
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* Helper method to find out whether this code fits on one byte
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*/
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private static boolean fitsOnOneByte(final int character,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) {
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int codePoint = character;
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if (codePointToOneByteCodeMap != null) {
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if (codePointToOneByteCodeMap.containsKey(character)) {
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codePoint = codePointToOneByteCodeMap.get(character);
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}
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}
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return codePoint >= FormatSpec.MINIMAL_ONE_BYTE_CHARACTER_VALUE
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&& codePoint <= FormatSpec.MAXIMAL_ONE_BYTE_CHARACTER_VALUE;
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}
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/**
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* Compute the size of a character given its character code.
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*
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* Char format is:
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* 1 byte = bbbbbbbb match
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* case 000xxxxx: xxxxx << 16 + next byte << 8 + next byte
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* else: if 00011111 (= 0x1F) : this is the terminator. This is a relevant choice because
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* unicode code points range from 0 to 0x10FFFF, so any 3-byte value starting with
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* 00011111 would be outside unicode.
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* else: iso-latin-1 code
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* This allows for the whole unicode range to be encoded, including chars outside of
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* the BMP. Also everything in the iso-latin-1 charset is only 1 byte, except control
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* characters which should never happen anyway (and still work, but take 3 bytes).
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*
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* @param character the character code.
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* @return the size in binary encoded-form, either 1 or 3 bytes.
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*/
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static int getCharSize(final int character,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) {
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// See char encoding in FusionDictionary.java
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if (fitsOnOneByte(character, codePointToOneByteCodeMap)) return 1;
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if (FormatSpec.INVALID_CHARACTER == character) return 1;
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return 3;
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}
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/**
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* Compute the byte size of a character array.
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*/
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static int getCharArraySize(final int[] chars,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) {
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int size = 0;
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for (int character : chars) size += getCharSize(character, codePointToOneByteCodeMap);
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return size;
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}
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/**
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* Writes a char array to a byte buffer.
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*
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* @param codePoints the code point array to write.
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* @param buffer the byte buffer to write to.
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* @param fromIndex the index in buffer to write the character array to.
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* @param codePointToOneByteCodeMap the map to convert the code point.
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* @return the index after the last character.
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*/
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static int writeCharArray(final int[] codePoints, final byte[] buffer, final int fromIndex,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) {
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int index = fromIndex;
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for (int codePoint : codePoints) {
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if (codePointToOneByteCodeMap != null) {
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if (codePointToOneByteCodeMap.containsKey(codePoint)) {
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// Convert code points
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codePoint = codePointToOneByteCodeMap.get(codePoint);
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}
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}
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if (1 == getCharSize(codePoint, codePointToOneByteCodeMap)) {
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buffer[index++] = (byte)codePoint;
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} else {
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buffer[index++] = (byte)(0xFF & (codePoint >> 16));
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buffer[index++] = (byte)(0xFF & (codePoint >> 8));
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buffer[index++] = (byte)(0xFF & codePoint);
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}
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}
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return index;
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}
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/**
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* Writes a string with our character format to a byte buffer.
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*
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* This will also write the terminator byte.
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*
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* @param buffer the byte buffer to write to.
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* @param origin the offset to write from.
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* @param word the string to write.
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* @return the size written, in bytes.
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*/
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static int writeString(final byte[] buffer, final int origin, final String word,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) {
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final int length = word.length();
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int index = origin;
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for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
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int codePoint = word.codePointAt(i);
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if (codePointToOneByteCodeMap != null) {
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if (codePointToOneByteCodeMap.containsKey(codePoint)) {
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// Convert code points
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codePoint = codePointToOneByteCodeMap.get(codePoint);
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}
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}
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if (1 == getCharSize(codePoint, codePointToOneByteCodeMap)) {
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buffer[index++] = (byte)codePoint;
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} else {
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buffer[index++] = (byte)(0xFF & (codePoint >> 16));
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buffer[index++] = (byte)(0xFF & (codePoint >> 8));
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buffer[index++] = (byte)(0xFF & codePoint);
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}
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}
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buffer[index++] = FormatSpec.PTNODE_CHARACTERS_TERMINATOR;
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return index - origin;
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}
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/**
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* Writes a string with our character format to an OutputStream.
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*
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* This will also write the terminator byte.
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*
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* @param stream the OutputStream to write to.
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* @param word the string to write.
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* @return the size written, in bytes.
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*/
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static int writeString(final OutputStream stream, final String word,
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final HashMap<Integer, Integer> codePointToOneByteCodeMap) throws IOException {
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final int length = word.length();
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int written = 0;
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for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
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final int codePoint = word.codePointAt(i);
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final int charSize = getCharSize(codePoint, codePointToOneByteCodeMap);
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if (1 == charSize) {
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stream.write((byte) codePoint);
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} else {
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stream.write((byte) (0xFF & (codePoint >> 16)));
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stream.write((byte) (0xFF & (codePoint >> 8)));
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stream.write((byte) (0xFF & codePoint));
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}
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written += charSize;
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}
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stream.write(FormatSpec.PTNODE_CHARACTERS_TERMINATOR);
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written += FormatSpec.PTNODE_TERMINATOR_SIZE;
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return written;
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}
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/**
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* Reads a string from a DictBuffer. This is the converse of the above method.
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*/
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static String readString(final DictBuffer dictBuffer) {
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final StringBuilder s = new StringBuilder();
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int character = readChar(dictBuffer);
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while (character != FormatSpec.INVALID_CHARACTER) {
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s.appendCodePoint(character);
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character = readChar(dictBuffer);
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}
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return s.toString();
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}
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/**
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* Reads a character from the buffer.
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*
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* This follows the character format documented earlier in this source file.
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*
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* @param dictBuffer the buffer, positioned over an encoded character.
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* @return the character code.
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*/
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static int readChar(final DictBuffer dictBuffer) {
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int character = dictBuffer.readUnsignedByte();
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if (!fitsOnOneByte(character, null)) {
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if (FormatSpec.PTNODE_CHARACTERS_TERMINATOR == character) {
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return FormatSpec.INVALID_CHARACTER;
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}
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character <<= 16;
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character += dictBuffer.readUnsignedShort();
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}
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return character;
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}
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}
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/**
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* Reads and returns the PtNode count out of a buffer and forwards the pointer.
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*/
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/* package */ static int readPtNodeCount(final DictBuffer dictBuffer) {
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final int msb = dictBuffer.readUnsignedByte();
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if (FormatSpec.MAX_PTNODES_FOR_ONE_BYTE_PTNODE_COUNT >= msb) {
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return msb;
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}
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return ((FormatSpec.MAX_PTNODES_FOR_ONE_BYTE_PTNODE_COUNT & msb) << 8)
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+ dictBuffer.readUnsignedByte();
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}
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/**
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* Finds, as a string, the word at the position passed as an argument.
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*
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* @param dictDecoder the dict decoder.
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* @param headerSize the size of the header.
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* @param pos the position to seek.
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* @return the word with its frequency, as a weighted string.
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*/
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@UsedForTesting
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/* package for tests */ static WeightedString getWordAtPosition(final DictDecoder dictDecoder,
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final int headerSize, final int pos) {
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final WeightedString result;
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final int originalPos = dictDecoder.getPosition();
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dictDecoder.setPosition(pos);
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result = getWordAtPositionWithoutParentAddress(dictDecoder, headerSize, pos);
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dictDecoder.setPosition(originalPos);
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return result;
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}
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private static WeightedString getWordAtPositionWithoutParentAddress(
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final DictDecoder dictDecoder, final int headerSize, final int pos) {
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dictDecoder.setPosition(headerSize);
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final int count = dictDecoder.readPtNodeCount();
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int groupPos = dictDecoder.getPosition();
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final StringBuilder builder = new StringBuilder();
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WeightedString result = null;
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PtNodeInfo last = null;
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for (int i = count - 1; i >= 0; --i) {
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PtNodeInfo info = dictDecoder.readPtNode(groupPos);
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groupPos = info.mEndAddress;
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if (info.mOriginalAddress == pos) {
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builder.append(new String(info.mCharacters, 0, info.mCharacters.length));
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result = new WeightedString(builder.toString(), info.mProbabilityInfo);
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break; // and return
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}
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if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
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if (info.mChildrenAddress > pos) {
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if (null == last) continue;
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builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
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dictDecoder.setPosition(last.mChildrenAddress);
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i = dictDecoder.readPtNodeCount();
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groupPos = last.mChildrenAddress + BinaryDictIOUtils.getPtNodeCountSize(i);
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last = null;
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continue;
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}
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last = info;
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}
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if (0 == i && BinaryDictIOUtils.hasChildrenAddress(last.mChildrenAddress)) {
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builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
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dictDecoder.setPosition(last.mChildrenAddress);
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i = dictDecoder.readPtNodeCount();
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groupPos = last.mChildrenAddress + BinaryDictIOUtils.getPtNodeCountSize(i);
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last = null;
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continue;
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}
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}
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return result;
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}
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/**
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* Helper method that brutally decodes a header from a byte array.
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*
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* @param headerBuffer a buffer containing the bytes of the header.
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* @return a hashmap of the attributes stored in the header
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*/
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@Nonnull
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public static HashMap<String, String> decodeHeaderAttributes(@Nonnull final byte[] headerBuffer)
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throws UnsupportedFormatException {
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final StringBuilder sb = new StringBuilder();
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final LinkedList<String> keyValues = new LinkedList<>();
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int index = 0;
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while (index < headerBuffer.length) {
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if (headerBuffer[index] == FormatSpec.PTNODE_CHARACTERS_TERMINATOR) {
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keyValues.add(sb.toString());
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sb.setLength(0);
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} else if (CharEncoding.fitsOnOneByte(headerBuffer[index] & 0xFF,
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null /* codePointTable */)) {
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sb.appendCodePoint(headerBuffer[index] & 0xFF);
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} else {
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sb.appendCodePoint(((headerBuffer[index] & 0xFF) << 16)
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+ ((headerBuffer[index + 1] & 0xFF) << 8)
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+ (headerBuffer[index + 2] & 0xFF));
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index += 2;
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}
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index += 1;
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}
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if ((keyValues.size() & 1) != 0) {
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throw new UnsupportedFormatException("Odd number of attributes");
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}
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final HashMap<String, String> attributes = new HashMap<>();
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for (int i = 0; i < keyValues.size(); i += 2) {
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attributes.put(keyValues.get(i), keyValues.get(i + 1));
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}
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return attributes;
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}
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/**
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* Helper method to pass a file name instead of a File object to isBinaryDictionary.
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*/
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public static boolean isBinaryDictionary(final String filename) {
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final File file = new File(filename);
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return isBinaryDictionary(file);
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}
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/**
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* Basic test to find out whether the file is a binary dictionary or not.
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*
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* @param file The file to test.
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* @return true if it's a binary dictionary, false otherwise
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*/
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public static boolean isBinaryDictionary(final File file) {
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final DictDecoder dictDecoder = BinaryDictIOUtils.getDictDecoder(file, 0, file.length());
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if (dictDecoder == null) {
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return false;
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}
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return dictDecoder.hasValidRawBinaryDictionary();
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}
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}
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