/*
* 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.CharEncoding;
import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.DictBuffer;
import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
import com.android.inputmethod.latin.makedict.FusionDictionary.PtNode;
import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
/**
* Encodes binary files for a FusionDictionary.
*
* All the methods in this class are static.
*
* TODO: Rename this class to DictEncoderUtils.
*/
public class BinaryDictEncoderUtils {
private static final boolean DBG = MakedictLog.DBG;
private BinaryDictEncoderUtils() {
// This utility class is not publicly instantiable.
}
// Arbitrary limit to how much passes we consider address size compression should
// terminate in. At the time of this writing, our largest dictionary completes
// compression in five passes.
// If the number of passes exceeds this number, makedict bails with an exception on
// suspicion that a bug might be causing an infinite loop.
private static final int MAX_PASSES = 24;
/**
* Compute the binary size of the character array.
*
* If only one character, this is the size of this character. If many, it's the sum of their
* sizes + 1 byte for the terminator.
*
* @param characters the character array
* @return the size of the char array, including the terminator if any
*/
static int getPtNodeCharactersSize(final int[] characters) {
int size = CharEncoding.getCharArraySize(characters);
if (characters.length > 1) size += FormatSpec.PTNODE_TERMINATOR_SIZE;
return size;
}
/**
* Compute the binary size of the character array in a PtNode
*
* If only one character, this is the size of this character. If many, it's the sum of their
* sizes + 1 byte for the terminator.
*
* @param ptNode the PtNode
* @return the size of the char array, including the terminator if any
*/
private static int getPtNodeCharactersSize(final PtNode ptNode) {
return getPtNodeCharactersSize(ptNode.mChars);
}
/**
* Compute the binary size of the PtNode count for a node array.
* @param nodeArray the nodeArray
* @return the size of the PtNode count, either 1 or 2 bytes.
*/
private static int getPtNodeCountSize(final PtNodeArray nodeArray) {
return BinaryDictIOUtils.getPtNodeCountSize(nodeArray.mData.size());
}
/**
* Compute the size of a shortcut in bytes.
*/
private static int getShortcutSize(final WeightedString shortcut) {
int size = FormatSpec.PTNODE_ATTRIBUTE_FLAGS_SIZE;
final String word = shortcut.mWord;
final int length = word.length();
for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
final int codePoint = word.codePointAt(i);
size += CharEncoding.getCharSize(codePoint);
}
size += FormatSpec.PTNODE_TERMINATOR_SIZE;
return size;
}
/**
* Compute the size of a shortcut list in bytes.
*
* This is known in advance and does not change according to position in the file
* like address lists do.
*/
static int getShortcutListSize(final ArrayList<WeightedString> shortcutList) {
if (null == shortcutList || shortcutList.isEmpty()) return 0;
int size = FormatSpec.PTNODE_SHORTCUT_LIST_SIZE_SIZE;
for (final WeightedString shortcut : shortcutList) {
size += getShortcutSize(shortcut);
}
return size;
}
/**
* Compute the maximum size of a PtNode, assuming 3-byte addresses for everything.
*
* @param ptNode the PtNode to compute the size of.
* @return the maximum size of the PtNode.
*/
private static int getPtNodeMaximumSize(final PtNode ptNode) {
int size = getNodeHeaderSize(ptNode);
if (ptNode.isTerminal()) {
// If terminal, one byte for the frequency.
size += FormatSpec.PTNODE_FREQUENCY_SIZE;
}
size += FormatSpec.PTNODE_MAX_ADDRESS_SIZE; // For children address
size += getShortcutListSize(ptNode.mShortcutTargets);
if (null != ptNode.mBigrams) {
size += (FormatSpec.PTNODE_ATTRIBUTE_FLAGS_SIZE
+ FormatSpec.PTNODE_ATTRIBUTE_MAX_ADDRESS_SIZE)
* ptNode.mBigrams.size();
}
return size;
}
/**
* Compute the maximum size of each PtNode of a PtNode array, assuming 3-byte addresses for
* everything, and caches it in the `mCachedSize' member of the nodes; deduce the size of
* the containing node array, and cache it it its 'mCachedSize' member.
*
* @param ptNodeArray the node array to compute the maximum size of.
*/
private static void calculatePtNodeArrayMaximumSize(final PtNodeArray ptNodeArray) {
int size = getPtNodeCountSize(ptNodeArray);
for (PtNode node : ptNodeArray.mData) {
final int nodeSize = getPtNodeMaximumSize(node);
node.mCachedSize = nodeSize;
size += nodeSize;
}
ptNodeArray.mCachedSize = size;
}
/**
* Compute the size of the header (flag + [parent address] + characters size) of a PtNode.
*
* @param ptNode the PtNode of which to compute the size of the header
*/
private static int getNodeHeaderSize(final PtNode ptNode) {
return FormatSpec.PTNODE_FLAGS_SIZE + getPtNodeCharactersSize(ptNode);
}
/**
* Compute the size, in bytes, that an address will occupy.
*
* This can be used either for children addresses (which are always positive) or for
* attribute, which may be positive or negative but
* store their sign bit separately.
*
* @param address the address
* @return the byte size.
*/
static int getByteSize(final int address) {
assert(address <= FormatSpec.UINT24_MAX);
if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
return 0;
} else if (Math.abs(address) <= FormatSpec.UINT8_MAX) {
return 1;
} else if (Math.abs(address) <= FormatSpec.UINT16_MAX) {
return 2;
} else {
return 3;
}
}
static int writeUIntToBuffer(final byte[] buffer, int position, final int value,
final int size) {
switch(size) {
case 4:
buffer[position++] = (byte) ((value >> 24) & 0xFF);
/* fall through */
case 3:
buffer[position++] = (byte) ((value >> 16) & 0xFF);
/* fall through */
case 2:
buffer[position++] = (byte) ((value >> 8) & 0xFF);
/* fall through */
case 1:
buffer[position++] = (byte) (value & 0xFF);
break;
default:
/* nop */
}
return position;
}
static void writeUIntToStream(final OutputStream stream, final int value, final int size)
throws IOException {
switch(size) {
case 4:
stream.write((value >> 24) & 0xFF);
/* fall through */
case 3:
stream.write((value >> 16) & 0xFF);
/* fall through */
case 2:
stream.write((value >> 8) & 0xFF);
/* fall through */
case 1:
stream.write(value & 0xFF);
break;
default:
/* nop */
}
}
@UsedForTesting
static void writeUIntToDictBuffer(final DictBuffer dictBuffer, final int value,
final int size) {
switch(size) {
case 4:
dictBuffer.put((byte) ((value >> 24) & 0xFF));
/* fall through */
case 3:
dictBuffer.put((byte) ((value >> 16) & 0xFF));
/* fall through */
case 2:
dictBuffer.put((byte) ((value >> 8) & 0xFF));
/* fall through */
case 1:
dictBuffer.put((byte) (value & 0xFF));
break;
default:
/* nop */
}
}
// End utility methods
// This method is responsible for finding a nice ordering of the nodes that favors run-time
// cache performance and dictionary size.
/* package for tests */ static ArrayList<PtNodeArray> flattenTree(
final PtNodeArray rootNodeArray) {
final int treeSize = FusionDictionary.countPtNodes(rootNodeArray);
MakedictLog.i("Counted nodes : " + treeSize);
final ArrayList<PtNodeArray> flatTree = new ArrayList<PtNodeArray>(treeSize);
return flattenTreeInner(flatTree, rootNodeArray);
}
private static ArrayList<PtNodeArray> flattenTreeInner(final ArrayList<PtNodeArray> list,
final PtNodeArray ptNodeArray) {
// Removing the node is necessary if the tails are merged, because we would then
// add the same node several times when we only want it once. A number of places in
// the code also depends on any node being only once in the list.
// Merging tails can only be done if there are no attributes. Searching for attributes
// in LatinIME code depends on a total breadth-first ordering, which merging tails
// breaks. If there are no attributes, it should be fine (and reduce the file size)
// to merge tails, and removing the node from the list would be necessary. However,
// we don't merge tails because breaking the breadth-first ordering would result in
// extreme overhead at bigram lookup time (it would make the search function O(n) instead
// of the current O(log(n)), where n=number of nodes in the dictionary which is pretty
// high).
// If no nodes are ever merged, we can't have the same node twice in the list, hence
// searching for duplicates in unnecessary. It is also very performance consuming,
// since `list' is an ArrayList so it's an O(n) operation that runs on all nodes, making
// this simple list.remove operation O(n*n) overall. On Android this overhead is very
// high.
// For future reference, the code to remove duplicate is a simple : list.remove(node);
list.add(ptNodeArray);
final ArrayList<PtNode> branches = ptNodeArray.mData;
for (PtNode ptNode : branches) {
if (null != ptNode.mChildren) flattenTreeInner(list, ptNode.mChildren);
}
return list;
}
/**
* Get the offset from a position inside a current node array to a target node array, during
* update.
*
* If the current node array is before the target node array, the target node array has not
* been updated yet, so we should return the offset from the old position of the current node
* array to the old position of the target node array. If on the other hand the target is
* before the current node array, it already has been updated, so we should return the offset
* from the new position in the current node array to the new position in the target node
* array.
*
* @param currentNodeArray node array containing the PtNode where the offset will be written
* @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
* @param targetNodeArray the target node array to get the offset to
* @return the offset to the target node array
*/
private static int getOffsetToTargetNodeArrayDuringUpdate(final PtNodeArray currentNodeArray,
final int offsetFromStartOfCurrentNodeArray, final PtNodeArray targetNodeArray) {
final boolean isTargetBeforeCurrent = (targetNodeArray.mCachedAddressBeforeUpdate
< currentNodeArray.mCachedAddressBeforeUpdate);
if (isTargetBeforeCurrent) {
return targetNodeArray.mCachedAddressAfterUpdate
- (currentNodeArray.mCachedAddressAfterUpdate
+ offsetFromStartOfCurrentNodeArray);
} else {
return targetNodeArray.mCachedAddressBeforeUpdate
- (currentNodeArray.mCachedAddressBeforeUpdate
+ offsetFromStartOfCurrentNodeArray);
}
}
/**
* Get the offset from a position inside a current node array to a target PtNode, during
* update.
*
* @param currentNodeArray node array containing the PtNode where the offset will be written
* @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
* @param targetPtNode the target PtNode to get the offset to
* @return the offset to the target PtNode
*/
// TODO: is there any way to factorize this method with the one above?
private static int getOffsetToTargetPtNodeDuringUpdate(final PtNodeArray currentNodeArray,
final int offsetFromStartOfCurrentNodeArray, final PtNode targetPtNode) {
final int oldOffsetBasePoint = currentNodeArray.mCachedAddressBeforeUpdate
+ offsetFromStartOfCurrentNodeArray;
final boolean isTargetBeforeCurrent = (targetPtNode.mCachedAddressBeforeUpdate
< oldOffsetBasePoint);
// If the target is before the current node array, then its address has already been
// updated. We can use the AfterUpdate member, and compare it to our own member after
// update. Otherwise, the AfterUpdate member is not updated yet, so we need to use the
// BeforeUpdate member, and of course we have to compare this to our own address before
// update.
if (isTargetBeforeCurrent) {
final int newOffsetBasePoint = currentNodeArray.mCachedAddressAfterUpdate
+ offsetFromStartOfCurrentNodeArray;
return targetPtNode.mCachedAddressAfterUpdate - newOffsetBasePoint;
} else {
return targetPtNode.mCachedAddressBeforeUpdate - oldOffsetBasePoint;
}
}
/**
* Computes the actual node array size, based on the cached addresses of the children nodes.
*
* Each node array stores its tentative address. During dictionary address computing, these
* are not final, but they can be used to compute the node array size (the node array size
* depends on the address of the children because the number of bytes necessary to store an
* address depends on its numeric value. The return value indicates whether the node array
* contents (as in, any of the addresses stored in the cache fields) have changed with
* respect to their previous value.
*
* @param ptNodeArray the node array to compute the size of.
* @param dict the dictionary in which the word/attributes are to be found.
* @return false if none of the cached addresses inside the node array changed, true otherwise.
*/
private static boolean computeActualPtNodeArraySize(final PtNodeArray ptNodeArray,
final FusionDictionary dict) {
boolean changed = false;
int size = getPtNodeCountSize(ptNodeArray);
for (PtNode ptNode : ptNodeArray.mData) {
ptNode.mCachedAddressAfterUpdate = ptNodeArray.mCachedAddressAfterUpdate + size;
if (ptNode.mCachedAddressAfterUpdate != ptNode.mCachedAddressBeforeUpdate) {
changed = true;
}
int nodeSize = getNodeHeaderSize(ptNode);
if (ptNode.isTerminal()) {
nodeSize += FormatSpec.PTNODE_FREQUENCY_SIZE;
}
if (null != ptNode.mChildren) {
nodeSize += getByteSize(getOffsetToTargetNodeArrayDuringUpdate(ptNodeArray,
nodeSize + size, ptNode.mChildren));
}
nodeSize += getShortcutListSize(ptNode.mShortcutTargets);
if (null != ptNode.mBigrams) {
for (WeightedString bigram : ptNode.mBigrams) {
final int offset = getOffsetToTargetPtNodeDuringUpdate(ptNodeArray,
nodeSize + size + FormatSpec.PTNODE_ATTRIBUTE_FLAGS_SIZE,
FusionDictionary.findWordInTree(dict.mRootNodeArray, bigram.mWord));
nodeSize += getByteSize(offset) + FormatSpec.PTNODE_ATTRIBUTE_FLAGS_SIZE;
}
}
ptNode.mCachedSize = nodeSize;
size += nodeSize;
}
if (ptNodeArray.mCachedSize != size) {
ptNodeArray.mCachedSize = size;
changed = true;
}
return changed;
}
/**
* Initializes the cached addresses of node arrays and their containing nodes from their size.
*
* @param flatNodes the list of node arrays.
* @return the byte size of the entire stack.
*/
private static int initializePtNodeArraysCachedAddresses(
final ArrayList<PtNodeArray> flatNodes) {
int nodeArrayOffset = 0;
for (final PtNodeArray nodeArray : flatNodes) {
nodeArray.mCachedAddressBeforeUpdate = nodeArrayOffset;
int nodeCountSize = getPtNodeCountSize(nodeArray);
int nodeffset = 0;
for (final PtNode ptNode : nodeArray.mData) {
ptNode.mCachedAddressBeforeUpdate = ptNode.mCachedAddressAfterUpdate =
nodeCountSize + nodeArrayOffset + nodeffset;
nodeffset += ptNode.mCachedSize;
}
nodeArrayOffset += nodeArray.mCachedSize;
}
return nodeArrayOffset;
}
/**
* Updates the cached addresses of node arrays after recomputing their new positions.
*
* @param flatNodes the list of node arrays.
*/
private static void updatePtNodeArraysCachedAddresses(final ArrayList<PtNodeArray> flatNodes) {
for (final PtNodeArray nodeArray : flatNodes) {
nodeArray.mCachedAddressBeforeUpdate = nodeArray.mCachedAddressAfterUpdate;
for (final PtNode ptNode : nodeArray.mData) {
ptNode.mCachedAddressBeforeUpdate = ptNode.mCachedAddressAfterUpdate;
}
}
}
/**
* Compute the addresses and sizes of an ordered list of PtNode arrays.
*
* This method takes a list of PtNode arrays and will update their cached address and size
* values so that they can be written into a file. It determines the smallest size each of the
* PtNode arrays can be given the addresses of its children and attributes, and store that into
* each PtNode.
* The order of the PtNode is given by the order of the array. This method makes no effort
* to find a good order; it only mechanically computes the size this order results in.
*
* @param dict the dictionary
* @param flatNodes the ordered list of PtNode arrays
* @return the same array it was passed. The nodes have been updated for address and size.
*/
/* package */ static ArrayList<PtNodeArray> computeAddresses(final FusionDictionary dict,
final ArrayList<PtNodeArray> flatNodes) {
// First get the worst possible sizes and offsets
for (final PtNodeArray n : flatNodes) {
calculatePtNodeArrayMaximumSize(n);
}
final int offset = initializePtNodeArraysCachedAddresses(flatNodes);
MakedictLog.i("Compressing the array addresses. Original size : " + offset);
MakedictLog.i("(Recursively seen size : " + offset + ")");
int passes = 0;
boolean changesDone = false;
do {
changesDone = false;
int ptNodeArrayStartOffset = 0;
for (final PtNodeArray ptNodeArray : flatNodes) {
ptNodeArray.mCachedAddressAfterUpdate = ptNodeArrayStartOffset;
final int oldNodeArraySize = ptNodeArray.mCachedSize;
final boolean changed = computeActualPtNodeArraySize(ptNodeArray, dict);
final int newNodeArraySize = ptNodeArray.mCachedSize;
if (oldNodeArraySize < newNodeArraySize) {
throw new RuntimeException("Increased size ?!");
}
ptNodeArrayStartOffset += newNodeArraySize;
changesDone |= changed;
}
updatePtNodeArraysCachedAddresses(flatNodes);
++passes;
if (passes > MAX_PASSES) throw new RuntimeException("Too many passes - probably a bug");
} while (changesDone);
final PtNodeArray lastPtNodeArray = flatNodes.get(flatNodes.size() - 1);
MakedictLog.i("Compression complete in " + passes + " passes.");
MakedictLog.i("After address compression : "
+ (lastPtNodeArray.mCachedAddressAfterUpdate + lastPtNodeArray.mCachedSize));
return flatNodes;
}
/**
* Sanity-checking method.
*
* This method checks a list of PtNode arrays for juxtaposition, that is, it will do
* nothing if each node array's cached address is actually the previous node array's address
* plus the previous node's size.
* If this is not the case, it will throw an exception.
*
* @param arrays the list of node arrays to check
*/
/* package */ static void checkFlatPtNodeArrayList(final ArrayList<PtNodeArray> arrays) {
int offset = 0;
int index = 0;
for (final PtNodeArray ptNodeArray : arrays) {
// BeforeUpdate and AfterUpdate addresses are the same here, so it does not matter
// which we use.
if (ptNodeArray.mCachedAddressAfterUpdate != offset) {
throw new RuntimeException("Wrong address for node " + index
+ " : expected " + offset + ", got " +
ptNodeArray.mCachedAddressAfterUpdate);
}
++index;
offset += ptNodeArray.mCachedSize;
}
}
/**
* Helper method to write a children position to a file.
*
* @param buffer the buffer to write to.
* @param index the index in the buffer to write the address to.
* @param position the position to write.
* @return the size in bytes the address actually took.
*/
/* package */ static int writeChildrenPosition(final byte[] buffer, int index,
final int position) {
switch (getByteSize(position)) {
case 1:
buffer[index++] = (byte)position;
return 1;
case 2:
buffer[index++] = (byte)(0xFF & (position >> 8));
buffer[index++] = (byte)(0xFF & position);
return 2;
case 3:
buffer[index++] = (byte)(0xFF & (position >> 16));
buffer[index++] = (byte)(0xFF & (position >> 8));
buffer[index++] = (byte)(0xFF & position);
return 3;
case 0:
return 0;
default:
throw new RuntimeException("Position " + position + " has a strange size");
}
}
/**
* Helper method to write a signed children position to a file.
*
* @param buffer the buffer to write to.
* @param index the index in the buffer to write the address to.
* @param position the position to write.
* @return the size in bytes the address actually took.
*/
/* package */ static int writeSignedChildrenPosition(final byte[] buffer, int index,
final int position) {
if (!BinaryDictIOUtils.hasChildrenAddress(position)) {
buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
} else {
final int absPosition = Math.abs(position);
buffer[index++] =
(byte)((position < 0 ? FormatSpec.MSB8 : 0) | (0xFF & (absPosition >> 16)));
buffer[index++] = (byte)(0xFF & (absPosition >> 8));
buffer[index++] = (byte)(0xFF & absPosition);
}
return 3;
}
/**
* Makes the flag value for a PtNode.
*
* @param hasMultipleChars whether the PtNode has multiple chars.
* @param isTerminal whether the PtNode is terminal.
* @param childrenAddressSize the size of a children address.
* @param hasShortcuts whether the PtNode has shortcuts.
* @param hasBigrams whether the PtNode has bigrams.
* @param isNotAWord whether the PtNode is not a word.
* @param isBlackListEntry whether the PtNode is a blacklist entry.
* @return the flags
*/
static int makePtNodeFlags(final boolean hasMultipleChars, final boolean isTerminal,
final int childrenAddressSize, final boolean hasShortcuts, final boolean hasBigrams,
final boolean isNotAWord, final boolean isBlackListEntry) {
byte flags = 0;
if (hasMultipleChars) flags |= FormatSpec.FLAG_HAS_MULTIPLE_CHARS;
if (isTerminal) flags |= FormatSpec.FLAG_IS_TERMINAL;
switch (childrenAddressSize) {
case 1:
flags |= FormatSpec.FLAG_CHILDREN_ADDRESS_TYPE_ONEBYTE;
break;
case 2:
flags |= FormatSpec.FLAG_CHILDREN_ADDRESS_TYPE_TWOBYTES;
break;
case 3:
flags |= FormatSpec.FLAG_CHILDREN_ADDRESS_TYPE_THREEBYTES;
break;
case 0:
flags |= FormatSpec.FLAG_CHILDREN_ADDRESS_TYPE_NOADDRESS;
break;
default:
throw new RuntimeException("Node with a strange address");
}
if (hasShortcuts) flags |= FormatSpec.FLAG_HAS_SHORTCUT_TARGETS;
if (hasBigrams) flags |= FormatSpec.FLAG_HAS_BIGRAMS;
if (isNotAWord) flags |= FormatSpec.FLAG_IS_NOT_A_WORD;
if (isBlackListEntry) flags |= FormatSpec.FLAG_IS_BLACKLISTED;
return flags;
}
/* package */ static byte makePtNodeFlags(final PtNode node, final int childrenOffset) {
return (byte) makePtNodeFlags(node.mChars.length > 1, node.isTerminal(),
getByteSize(childrenOffset),
node.mShortcutTargets != null && !node.mShortcutTargets.isEmpty(),
node.mBigrams != null && !node.mBigrams.isEmpty(),
node.mIsNotAWord, node.mIsBlacklistEntry);
}
/**
* Makes the flag value for a bigram.
*
* @param more whether there are more bigrams after this one.
* @param offset the offset of the bigram.
* @param bigramFrequency the frequency of the bigram, 0..255.
* @param unigramFrequency the unigram frequency of the same word, 0..255.
* @param word the second bigram, for debugging purposes
* @return the flags
*/
/* package */ static final int makeBigramFlags(final boolean more, final int offset,
int bigramFrequency, final int unigramFrequency, final String word) {
int bigramFlags = (more ? FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_HAS_NEXT : 0)
+ (offset < 0 ? FormatSpec.FLAG_BIGRAM_ATTR_OFFSET_NEGATIVE : 0);
switch (getByteSize(offset)) {
case 1:
bigramFlags |= FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_ONEBYTE;
break;
case 2:
bigramFlags |= FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_TWOBYTES;
break;
case 3:
bigramFlags |= FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_THREEBYTES;
break;
default:
throw new RuntimeException("Strange offset size");
}
if (unigramFrequency > bigramFrequency) {
MakedictLog.e("Unigram freq is superior to bigram freq for \"" + word
+ "\". Bigram freq is " + bigramFrequency + ", unigram freq for "
+ word + " is " + unigramFrequency);
bigramFrequency = unigramFrequency;
}
bigramFlags += getBigramFrequencyDiff(unigramFrequency, bigramFrequency)
& FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_FREQUENCY;
return bigramFlags;
}
public static int getBigramFrequencyDiff(final int unigramFrequency,
final int bigramFrequency) {
// We compute the difference between 255 (which means probability = 1) and the
// unigram score. We split this into a number of discrete steps.
// Now, the steps are numbered 0~15; 0 represents an increase of 1 step while 15
// represents an increase of 16 steps: a value of 15 will be interpreted as the median
// value of the 16th step. In all justice, if the bigram frequency is low enough to be
// rounded below the first step (which means it is less than half a step higher than the
// unigram frequency) then the unigram frequency itself is the best approximation of the
// bigram freq that we could possibly supply, hence we should *not* include this bigram
// in the file at all.
// until this is done, we'll write 0 and slightly overestimate this case.
// In other words, 0 means "between 0.5 step and 1.5 step", 1 means "between 1.5 step
// and 2.5 steps", and 15 means "between 15.5 steps and 16.5 steps". So we want to
// divide our range [unigramFreq..MAX_TERMINAL_FREQUENCY] in 16.5 steps to get the
// step size. Then we compute the start of the first step (the one where value 0 starts)
// by adding half-a-step to the unigramFrequency. From there, we compute the integer
// number of steps to the bigramFrequency. One last thing: we want our steps to include
// their lower bound and exclude their higher bound so we need to have the first step
// start at exactly 1 unit higher than floor(unigramFreq + half a step).
// Note : to reconstruct the score, the dictionary reader will need to divide
// MAX_TERMINAL_FREQUENCY - unigramFreq by 16.5 likewise to get the value of the step,
// and add (discretizedFrequency + 0.5 + 0.5) times this value to get the best
// approximation. (0.5 to get the first step start, and 0.5 to get the middle of the
// step pointed by the discretized frequency.
final float stepSize =
(FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
/ (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
final float firstStepStart = 1 + unigramFrequency + (stepSize / 2.0f);
final int discretizedFrequency = (int)((bigramFrequency - firstStepStart) / stepSize);
// If the bigram freq is less than half-a-step higher than the unigram freq, we get -1
// here. The best approximation would be the unigram freq itself, so we should not
// include this bigram in the dictionary. For now, register as 0, and live with the
// small over-estimation that we get in this case. TODO: actually remove this bigram
// if discretizedFrequency < 0.
return discretizedFrequency > 0 ? discretizedFrequency : 0;
}
/**
* Makes the flag value for a shortcut.
*
* @param more whether there are more attributes after this one.
* @param frequency the frequency of the attribute, 0..15
* @return the flags
*/
static final int makeShortcutFlags(final boolean more, final int frequency) {
return (more ? FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_HAS_NEXT : 0)
+ (frequency & FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_FREQUENCY);
}
/* package */ static final int getChildrenPosition(final PtNode ptNode) {
int positionOfChildrenPosField = ptNode.mCachedAddressAfterUpdate
+ getNodeHeaderSize(ptNode);
if (ptNode.isTerminal()) {
// A terminal node has the frequency.
// If positionOfChildrenPosField is incorrect, we may crash when jumping to the children
// position.
positionOfChildrenPosField += FormatSpec.PTNODE_FREQUENCY_SIZE;
}
return null == ptNode.mChildren ? FormatSpec.NO_CHILDREN_ADDRESS
: ptNode.mChildren.mCachedAddressAfterUpdate - positionOfChildrenPosField;
}
/**
* Write a PtNodeArray. The PtNodeArray is expected to have its final position cached.
*
* @param dict the dictionary the node array is a part of (for relative offsets).
* @param dictEncoder the dictionary encoder.
* @param ptNodeArray the node array to write.
*/
@SuppressWarnings("unused")
/* package */ static void writePlacedPtNodeArray(final FusionDictionary dict,
final DictEncoder dictEncoder, final PtNodeArray ptNodeArray) {
// TODO: Make the code in common with BinaryDictIOUtils#writePtNode
dictEncoder.setPosition(ptNodeArray.mCachedAddressAfterUpdate);
final int ptNodeCount = ptNodeArray.mData.size();
dictEncoder.writePtNodeCount(ptNodeCount);
final int parentPosition =
(ptNodeArray.mCachedParentAddress == FormatSpec.NO_PARENT_ADDRESS)
? FormatSpec.NO_PARENT_ADDRESS
: ptNodeArray.mCachedParentAddress + ptNodeArray.mCachedAddressAfterUpdate;
for (int i = 0; i < ptNodeCount; ++i) {
final PtNode ptNode = ptNodeArray.mData.get(i);
if (dictEncoder.getPosition() != ptNode.mCachedAddressAfterUpdate) {
throw new RuntimeException("Bug: write index is not the same as the cached address "
+ "of the node : " + dictEncoder.getPosition() + " <> "
+ ptNode.mCachedAddressAfterUpdate);
}
// Sanity checks.
if (DBG && ptNode.getProbability() > FormatSpec.MAX_TERMINAL_FREQUENCY) {
throw new RuntimeException("A node has a frequency > "
+ FormatSpec.MAX_TERMINAL_FREQUENCY
+ " : " + ptNode.mProbabilityInfo.toString());
}
dictEncoder.writePtNode(ptNode, dict);
}
if (dictEncoder.getPosition() != ptNodeArray.mCachedAddressAfterUpdate
+ ptNodeArray.mCachedSize) {
throw new RuntimeException("Not the same size : written "
+ (dictEncoder.getPosition() - ptNodeArray.mCachedAddressAfterUpdate)
+ " bytes from a node that should have " + ptNodeArray.mCachedSize + " bytes");
}
}
/**
* Dumps a collection of useful statistics about a list of PtNode arrays.
*
* This prints purely informative stuff, like the total estimated file size, the
* number of PtNode arrays, of PtNodes, the repartition of each address size, etc
*
* @param ptNodeArrays the list of PtNode arrays.
*/
/* package */ static void showStatistics(ArrayList<PtNodeArray> ptNodeArrays) {
int firstTerminalAddress = Integer.MAX_VALUE;
int lastTerminalAddress = Integer.MIN_VALUE;
int size = 0;
int ptNodes = 0;
int maxNodes = 0;
int maxRuns = 0;
for (final PtNodeArray ptNodeArray : ptNodeArrays) {
if (maxNodes < ptNodeArray.mData.size()) maxNodes = ptNodeArray.mData.size();
for (final PtNode ptNode : ptNodeArray.mData) {
++ptNodes;
if (ptNode.mChars.length > maxRuns) maxRuns = ptNode.mChars.length;
if (ptNode.isTerminal()) {
if (ptNodeArray.mCachedAddressAfterUpdate < firstTerminalAddress)
firstTerminalAddress = ptNodeArray.mCachedAddressAfterUpdate;
if (ptNodeArray.mCachedAddressAfterUpdate > lastTerminalAddress)
lastTerminalAddress = ptNodeArray.mCachedAddressAfterUpdate;
}
}
if (ptNodeArray.mCachedAddressAfterUpdate + ptNodeArray.mCachedSize > size) {
size = ptNodeArray.mCachedAddressAfterUpdate + ptNodeArray.mCachedSize;
}
}
final int[] ptNodeCounts = new int[maxNodes + 1];
final int[] runCounts = new int[maxRuns + 1];
for (final PtNodeArray ptNodeArray : ptNodeArrays) {
++ptNodeCounts[ptNodeArray.mData.size()];
for (final PtNode ptNode : ptNodeArray.mData) {
++runCounts[ptNode.mChars.length];
}
}
MakedictLog.i("Statistics:\n"
+ " total file size " + size + "\n"
+ " " + ptNodeArrays.size() + " node arrays\n"
+ " " + ptNodes + " PtNodes (" + ((float)ptNodes / ptNodeArrays.size())
+ " PtNodes per node)\n"
+ " first terminal at " + firstTerminalAddress + "\n"
+ " last terminal at " + lastTerminalAddress + "\n"
+ " PtNode stats : max = " + maxNodes);
for (int i = 0; i < ptNodeCounts.length; ++i) {
MakedictLog.i(" " + i + " : " + ptNodeCounts[i]);
}
MakedictLog.i(" Character run stats : max = " + maxRuns);
for (int i = 0; i < runCounts.length; ++i) {
MakedictLog.i(" " + i + " : " + runCounts[i]);
}
}
/**
* Writes a file header to an output stream.
*
* @param destination the stream to write the file header to.
* @param dict the dictionary to write.
* @param formatOptions file format options.
* @return the size of the header.
*/
/* package */ static int writeDictionaryHeader(final OutputStream destination,
final FusionDictionary dict, final FormatOptions formatOptions)
throws IOException, UnsupportedFormatException {
final int version = formatOptions.mVersion;
if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
|| version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
throw new UnsupportedFormatException("Requested file format version " + version
+ ", but this implementation only supports versions "
+ FormatSpec.MINIMUM_SUPPORTED_VERSION + " through "
+ FormatSpec.MAXIMUM_SUPPORTED_VERSION);
}
ByteArrayOutputStream headerBuffer = new ByteArrayOutputStream(256);
// The magic number in big-endian order.
// Magic number for all versions.
headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 24)));
headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 16)));
headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 8)));
headerBuffer.write((byte) (0xFF & FormatSpec.MAGIC_NUMBER));
// Dictionary version.
headerBuffer.write((byte) (0xFF & (version >> 8)));
headerBuffer.write((byte) (0xFF & version));
// Options flags
// TODO: Remove this field.
final int options = 0;
headerBuffer.write((byte) (0xFF & (options >> 8)));
headerBuffer.write((byte) (0xFF & options));
final int headerSizeOffset = headerBuffer.size();
// Placeholder to be written later with header size.
for (int i = 0; i < 4; ++i) {
headerBuffer.write(0);
}
// Write out the options.
for (final String key : dict.mOptions.mAttributes.keySet()) {
final String value = dict.mOptions.mAttributes.get(key);
CharEncoding.writeString(headerBuffer, key);
CharEncoding.writeString(headerBuffer, value);
}
final int size = headerBuffer.size();
final byte[] bytes = headerBuffer.toByteArray();
// Write out the header size.
bytes[headerSizeOffset] = (byte) (0xFF & (size >> 24));
bytes[headerSizeOffset + 1] = (byte) (0xFF & (size >> 16));
bytes[headerSizeOffset + 2] = (byte) (0xFF & (size >> 8));
bytes[headerSizeOffset + 3] = (byte) (0xFF & (size >> 0));
destination.write(bytes);
headerBuffer.close();
return size;
}
}