/* * 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 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 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 flattenTree( final PtNodeArray rootNodeArray) { final int treeSize = FusionDictionary.countPtNodes(rootNodeArray); MakedictLog.i("Counted nodes : " + treeSize); final ArrayList flatTree = new ArrayList<>(treeSize); return flattenTreeInner(flatTree, rootNodeArray); } private static ArrayList flattenTreeInner(final ArrayList 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 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 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 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 computeAddresses(final FusionDictionary dict, final ArrayList 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 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 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); } /** * 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; } }