diff options
Diffstat (limited to 'java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java')
| -rw-r--r-- | java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java | 993 |
1 files changed, 993 insertions, 0 deletions
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java new file mode 100644 index 000000000..85219e485 --- /dev/null +++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java @@ -0,0 +1,993 @@ +/* + * 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.latin.makedict.BinaryDictDecoder.CharEncoding; +import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions; +import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup; +import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions; +import com.android.inputmethod.latin.makedict.FusionDictionary.Node; +import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString; + +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.OutputStream; +import java.util.ArrayList; +import java.util.Iterator; + +/** + * Encodes binary files for a FusionDictionary. + * + * All the methods in this class are static. + */ +public class BinaryDictEncoder { + + private static final boolean DBG = MakedictLog.DBG; + + private BinaryDictEncoder() { + // 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 getGroupCharactersSize(final int[] characters) { + int size = CharEncoding.getCharArraySize(characters); + if (characters.length > 1) size += FormatSpec.GROUP_TERMINATOR_SIZE; + return size; + } + + /** + * Compute the binary size of the character array in a group + * + * 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 group the group + * @return the size of the char array, including the terminator if any + */ + private static int getGroupCharactersSize(final CharGroup group) { + return getGroupCharactersSize(group.mChars); + } + + /** + * Compute the binary size of the group count for a node + * @param node the node + * @return the size of the group count, either 1 or 2 bytes. + */ + private static int getGroupCountSize(final Node node) { + return BinaryDictIOUtils.getGroupCountSize(node.mData.size()); + } + + /** + * Compute the size of a shortcut in bytes. + */ + private static int getShortcutSize(final WeightedString shortcut) { + int size = FormatSpec.GROUP_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.GROUP_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) return 0; + int size = FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE; + for (final WeightedString shortcut : shortcutList) { + size += getShortcutSize(shortcut); + } + return size; + } + + /** + * Compute the maximum size of a CharGroup, assuming 3-byte addresses for everything. + * + * @param group the CharGroup to compute the size of. + * @param options file format options. + * @return the maximum size of the group. + */ + private static int getCharGroupMaximumSize(final CharGroup group, final FormatOptions options) { + int size = getGroupHeaderSize(group, options); + // If terminal, one byte for the frequency + if (group.isTerminal()) size += FormatSpec.GROUP_FREQUENCY_SIZE; + size += FormatSpec.GROUP_MAX_ADDRESS_SIZE; // For children address + size += getShortcutListSize(group.mShortcutTargets); + if (null != group.mBigrams) { + size += (FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE + + FormatSpec.GROUP_ATTRIBUTE_MAX_ADDRESS_SIZE) + * group.mBigrams.size(); + } + return size; + } + + /** + * Compute the maximum size of a node, assuming 3-byte addresses for everything, and caches + * it in the 'actualSize' member of the node. + * + * @param node the node to compute the maximum size of. + * @param options file format options. + */ + private static void calculateNodeMaximumSize(final Node node, final FormatOptions options) { + int size = getGroupCountSize(node); + for (CharGroup g : node.mData) { + final int groupSize = getCharGroupMaximumSize(g, options); + g.mCachedSize = groupSize; + size += groupSize; + } + if (options.mSupportsDynamicUpdate) { + size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE; + } + node.mCachedSize = size; + } + + /** + * Compute the size of the header (flag + [parent address] + characters size) of a CharGroup. + * + * @param group the group of which to compute the size of the header + * @param options file format options. + */ + private static int getGroupHeaderSize(final CharGroup group, final FormatOptions options) { + if (BinaryDictIOUtils.supportsDynamicUpdate(options)) { + return FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE + + getGroupCharactersSize(group); + } else { + return FormatSpec.GROUP_FLAGS_SIZE + getGroupCharactersSize(group); + } + } + + /** + * 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; + } + } + + // 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<Node> flattenTree(final Node root) { + final int treeSize = FusionDictionary.countCharGroups(root); + MakedictLog.i("Counted nodes : " + treeSize); + final ArrayList<Node> flatTree = new ArrayList<Node>(treeSize); + return flattenTreeInner(flatTree, root); + } + + private static ArrayList<Node> flattenTreeInner(final ArrayList<Node> list, final Node node) { + // 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(node); + final ArrayList<CharGroup> branches = node.mData; + final int nodeSize = branches.size(); + for (CharGroup group : branches) { + if (null != group.mChildren) flattenTreeInner(list, group.mChildren); + } + return list; + } + + /** + * Get the offset from a position inside a current node to a target node, during update. + * + * If the current node is before the target node, the target node has not been updated yet, + * so we should return the offset from the old position of the current node to the old position + * of the target node. If on the other hand the target is before the current node, it already + * has been updated, so we should return the offset from the new position in the current node + * to the new position in the target node. + * @param currentNode the node containing the CharGroup where the offset will be written + * @param offsetFromStartOfCurrentNode the offset, in bytes, from the start of currentNode + * @param targetNode the target node to get the offset to + * @return the offset to the target node + */ + private static int getOffsetToTargetNodeDuringUpdate(final Node currentNode, + final int offsetFromStartOfCurrentNode, final Node targetNode) { + final boolean isTargetBeforeCurrent = (targetNode.mCachedAddressBeforeUpdate + < currentNode.mCachedAddressBeforeUpdate); + if (isTargetBeforeCurrent) { + return targetNode.mCachedAddressAfterUpdate + - (currentNode.mCachedAddressAfterUpdate + offsetFromStartOfCurrentNode); + } else { + return targetNode.mCachedAddressBeforeUpdate + - (currentNode.mCachedAddressBeforeUpdate + offsetFromStartOfCurrentNode); + } + } + + /** + * Get the offset from a position inside a current node to a target CharGroup, during update. + * @param currentNode the node containing the CharGroup where the offset will be written + * @param offsetFromStartOfCurrentNode the offset, in bytes, from the start of currentNode + * @param targetCharGroup the target CharGroup to get the offset to + * @return the offset to the target CharGroup + */ + // TODO: is there any way to factorize this method with the one above? + private static int getOffsetToTargetCharGroupDuringUpdate(final Node currentNode, + final int offsetFromStartOfCurrentNode, final CharGroup targetCharGroup) { + final int oldOffsetBasePoint = currentNode.mCachedAddressBeforeUpdate + + offsetFromStartOfCurrentNode; + final boolean isTargetBeforeCurrent = (targetCharGroup.mCachedAddressBeforeUpdate + < oldOffsetBasePoint); + // If the target is before the current node, 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 = currentNode.mCachedAddressAfterUpdate + + offsetFromStartOfCurrentNode; + return targetCharGroup.mCachedAddressAfterUpdate - newOffsetBasePoint; + } else { + return targetCharGroup.mCachedAddressBeforeUpdate - oldOffsetBasePoint; + } + } + + /** + * Computes the actual node size, based on the cached addresses of the children nodes. + * + * Each node stores its tentative address. During dictionary address computing, these + * are not final, but they can be used to compute the node size (the node 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 + * contents (as in, any of the addresses stored in the cache fields) have changed with + * respect to their previous value. + * + * @param node the node to compute the size of. + * @param dict the dictionary in which the word/attributes are to be found. + * @param formatOptions file format options. + * @return false if none of the cached addresses inside the node changed, true otherwise. + */ + private static boolean computeActualNodeSize(final Node node, final FusionDictionary dict, + final FormatOptions formatOptions) { + boolean changed = false; + int size = getGroupCountSize(node); + for (CharGroup group : node.mData) { + group.mCachedAddressAfterUpdate = node.mCachedAddressAfterUpdate + size; + if (group.mCachedAddressAfterUpdate != group.mCachedAddressBeforeUpdate) { + changed = true; + } + int groupSize = getGroupHeaderSize(group, formatOptions); + if (group.isTerminal()) groupSize += FormatSpec.GROUP_FREQUENCY_SIZE; + if (null == group.mChildren && formatOptions.mSupportsDynamicUpdate) { + groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE; + } else if (null != group.mChildren) { + if (formatOptions.mSupportsDynamicUpdate) { + groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE; + } else { + groupSize += getByteSize(getOffsetToTargetNodeDuringUpdate(node, + groupSize + size, group.mChildren)); + } + } + groupSize += getShortcutListSize(group.mShortcutTargets); + if (null != group.mBigrams) { + for (WeightedString bigram : group.mBigrams) { + final int offset = getOffsetToTargetCharGroupDuringUpdate(node, + groupSize + size + FormatSpec.GROUP_FLAGS_SIZE, + FusionDictionary.findWordInTree(dict.mRoot, bigram.mWord)); + groupSize += getByteSize(offset) + FormatSpec.GROUP_FLAGS_SIZE; + } + } + group.mCachedSize = groupSize; + size += groupSize; + } + if (formatOptions.mSupportsDynamicUpdate) { + size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE; + } + if (node.mCachedSize != size) { + node.mCachedSize = size; + changed = true; + } + return changed; + } + + /** + * Initializes the cached addresses of nodes from their size. + * + * @param flatNodes the array of nodes. + * @param formatOptions file format options. + * @return the byte size of the entire stack. + */ + private static int initializeNodesCachedAddresses(final ArrayList<Node> flatNodes, + final FormatOptions formatOptions) { + int nodeOffset = 0; + for (final Node n : flatNodes) { + n.mCachedAddressBeforeUpdate = nodeOffset; + int groupCountSize = getGroupCountSize(n); + int groupOffset = 0; + for (final CharGroup g : n.mData) { + g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate = + groupCountSize + nodeOffset + groupOffset; + groupOffset += g.mCachedSize; + } + final int nodeSize = groupCountSize + groupOffset + + (formatOptions.mSupportsDynamicUpdate + ? FormatSpec.FORWARD_LINK_ADDRESS_SIZE : 0); + nodeOffset += n.mCachedSize; + } + return nodeOffset; + } + + /** + * Updates the cached addresses of nodes after recomputing their new positions. + * + * @param flatNodes the array of nodes. + */ + private static void updateNodeCachedAddresses(final ArrayList<Node> flatNodes) { + for (final Node n : flatNodes) { + n.mCachedAddressBeforeUpdate = n.mCachedAddressAfterUpdate; + for (final CharGroup g : n.mData) { + g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate; + } + } + } + + /** + * Compute the cached parent addresses after all has been updated. + * + * The parent addresses are used by some binary formats at write-to-disk time. Not all formats + * need them. In particular, version 2 does not need them, and version 3 does. + * + * @param flatNodes the flat array of nodes to fill in + */ + private static void computeParentAddresses(final ArrayList<Node> flatNodes) { + for (final Node node : flatNodes) { + for (final CharGroup group : node.mData) { + if (null != group.mChildren) { + // Assign my address to children's parent address + // Here BeforeUpdate and AfterUpdate addresses have the same value, so it + // does not matter which we use. + group.mChildren.mCachedParentAddress = group.mCachedAddressAfterUpdate + - group.mChildren.mCachedAddressAfterUpdate; + } + } + } + } + + /** + * Compute the addresses and sizes of an ordered node array. + * + * This method takes a node array and will update its cached address and size values + * so that they can be written into a file. It determines the smallest size each of the + * nodes can be given the addresses of its children and attributes, and store that into + * each node. + * The order of the node 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 array of nodes + * @param formatOptions file format options. + * @return the same array it was passed. The nodes have been updated for address and size. + */ + private static ArrayList<Node> computeAddresses(final FusionDictionary dict, + final ArrayList<Node> flatNodes, final FormatOptions formatOptions) { + // First get the worst possible sizes and offsets + for (final Node n : flatNodes) calculateNodeMaximumSize(n, formatOptions); + final int offset = initializeNodesCachedAddresses(flatNodes, formatOptions); + + 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 nodeStartOffset = 0; + for (final Node n : flatNodes) { + n.mCachedAddressAfterUpdate = nodeStartOffset; + final int oldNodeSize = n.mCachedSize; + final boolean changed = computeActualNodeSize(n, dict, formatOptions); + final int newNodeSize = n.mCachedSize; + if (oldNodeSize < newNodeSize) throw new RuntimeException("Increased size ?!"); + nodeStartOffset += newNodeSize; + changesDone |= changed; + } + updateNodeCachedAddresses(flatNodes); + ++passes; + if (passes > MAX_PASSES) throw new RuntimeException("Too many passes - probably a bug"); + } while (changesDone); + + if (formatOptions.mSupportsDynamicUpdate) { + computeParentAddresses(flatNodes); + } + final Node lastNode = flatNodes.get(flatNodes.size() - 1); + MakedictLog.i("Compression complete in " + passes + " passes."); + MakedictLog.i("After address compression : " + + (lastNode.mCachedAddressAfterUpdate + lastNode.mCachedSize)); + + return flatNodes; + } + + /** + * Sanity-checking method. + * + * This method checks an array of node for juxtaposition, that is, it will do + * nothing if each node's cached address is actually the previous node's address + * plus the previous node's size. + * If this is not the case, it will throw an exception. + * + * @param array the array node to check + */ + private static void checkFlatNodeArray(final ArrayList<Node> array) { + int offset = 0; + int index = 0; + for (final Node n : array) { + // BeforeUpdate and AfterUpdate addresses are the same here, so it does not matter + // which we use. + if (n.mCachedAddressAfterUpdate != offset) { + throw new RuntimeException("Wrong address for node " + index + + " : expected " + offset + ", got " + n.mCachedAddressAfterUpdate); + } + ++index; + offset += n.mCachedSize; + } + } + + /** + * Helper method to write a variable-size address to a file. + * + * @param buffer the buffer to write to. + * @param index the index in the buffer to write the address to. + * @param address the address to write. + * @return the size in bytes the address actually took. + */ + private static int writeVariableAddress(final byte[] buffer, int index, final int address) { + switch (getByteSize(address)) { + case 1: + buffer[index++] = (byte)address; + return 1; + case 2: + buffer[index++] = (byte)(0xFF & (address >> 8)); + buffer[index++] = (byte)(0xFF & address); + return 2; + case 3: + buffer[index++] = (byte)(0xFF & (address >> 16)); + buffer[index++] = (byte)(0xFF & (address >> 8)); + buffer[index++] = (byte)(0xFF & address); + return 3; + case 0: + return 0; + default: + throw new RuntimeException("Address " + address + " has a strange size"); + } + } + + /** + * Helper method to write a variable-size signed address to a file. + * + * @param buffer the buffer to write to. + * @param index the index in the buffer to write the address to. + * @param address the address to write. + * @return the size in bytes the address actually took. + */ + private static int writeVariableSignedAddress(final byte[] buffer, int index, + final int address) { + if (!BinaryDictIOUtils.hasChildrenAddress(address)) { + buffer[index] = buffer[index + 1] = buffer[index + 2] = 0; + } else { + final int absAddress = Math.abs(address); + buffer[index++] = + (byte)((address < 0 ? FormatSpec.MSB8 : 0) | (0xFF & (absAddress >> 16))); + buffer[index++] = (byte)(0xFF & (absAddress >> 8)); + buffer[index++] = (byte)(0xFF & absAddress); + } + return 3; + } + + /** + * Makes the flag value for a char group. + * + * @param hasMultipleChars whether the group has multiple chars. + * @param isTerminal whether the group is terminal. + * @param childrenAddressSize the size of a children address. + * @param hasShortcuts whether the group has shortcuts. + * @param hasBigrams whether the group has bigrams. + * @param isNotAWord whether the group is not a word. + * @param isBlackListEntry whether the group is a blacklist entry. + * @param formatOptions file format options. + * @return the flags + */ + static int makeCharGroupFlags(final boolean hasMultipleChars, final boolean isTerminal, + final int childrenAddressSize, final boolean hasShortcuts, final boolean hasBigrams, + final boolean isNotAWord, final boolean isBlackListEntry, + final FormatOptions formatOptions) { + byte flags = 0; + if (hasMultipleChars) flags |= FormatSpec.FLAG_HAS_MULTIPLE_CHARS; + if (isTerminal) flags |= FormatSpec.FLAG_IS_TERMINAL; + if (formatOptions.mSupportsDynamicUpdate) { + flags |= FormatSpec.FLAG_IS_NOT_MOVED; + } else if (true) { + switch (childrenAddressSize) { + case 1: + flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE; + break; + case 2: + flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES; + break; + case 3: + flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES; + break; + case 0: + flags |= FormatSpec.FLAG_GROUP_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; + } + + private static byte makeCharGroupFlags(final CharGroup group, final int groupAddress, + final int childrenOffset, final FormatOptions formatOptions) { + return (byte) makeCharGroupFlags(group.mChars.length > 1, group.mFrequency >= 0, + getByteSize(childrenOffset), group.mShortcutTargets != null, group.mBigrams != null, + group.mIsNotAWord, group.mIsBlacklistEntry, formatOptions); + } + + /** + * 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 + */ + private static final int makeBigramFlags(final boolean more, final int offset, + int bigramFrequency, final int unigramFrequency, final String word) { + int bigramFlags = (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0) + + (offset < 0 ? FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE : 0); + switch (getByteSize(offset)) { + case 1: + bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE; + break; + case 2: + bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES; + break; + case 3: + bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_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; + } + // 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. + final int finalBigramFrequency = discretizedFrequency > 0 ? discretizedFrequency : 0; + bigramFlags += finalBigramFrequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY; + return bigramFlags; + } + + /** + * Makes the 2-byte value for options flags. + */ + private static final int makeOptionsValue(final FusionDictionary dictionary, + final FormatOptions formatOptions) { + final DictionaryOptions options = dictionary.mOptions; + final boolean hasBigrams = dictionary.hasBigrams(); + return (options.mFrenchLigatureProcessing ? FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG : 0) + + (options.mGermanUmlautProcessing ? FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG : 0) + + (hasBigrams ? FormatSpec.CONTAINS_BIGRAMS_FLAG : 0) + + (formatOptions.mSupportsDynamicUpdate ? FormatSpec.SUPPORTS_DYNAMIC_UPDATE : 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_ATTRIBUTE_HAS_NEXT : 0) + + (frequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY); + } + + private static final int writeParentAddress(final byte[] buffer, final int index, + final int address, final FormatOptions formatOptions) { + if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) { + if (address == FormatSpec.NO_PARENT_ADDRESS) { + buffer[index] = buffer[index + 1] = buffer[index + 2] = 0; + } else { + final int absAddress = Math.abs(address); + assert(absAddress <= FormatSpec.SINT24_MAX); + buffer[index] = (byte)((address < 0 ? FormatSpec.MSB8 : 0) + | ((absAddress >> 16) & 0xFF)); + buffer[index + 1] = (byte)((absAddress >> 8) & 0xFF); + buffer[index + 2] = (byte)(absAddress & 0xFF); + } + return index + 3; + } else { + return index; + } + } + + /** + * Write a node to memory. The node is expected to have its final position cached. + * + * This can be an empty map, but the more is inside the faster the lookups will be. It can + * be carried on as long as nodes do not move. + * + * @param dict the dictionary the node is a part of (for relative offsets). + * @param buffer the memory buffer to write to. + * @param node the node to write. + * @param formatOptions file format options. + * @return the address of the END of the node. + */ + @SuppressWarnings("unused") + private static int writePlacedNode(final FusionDictionary dict, byte[] buffer, + final Node node, final FormatOptions formatOptions) { + // TODO: Make the code in common with BinaryDictIOUtils#writeCharGroup + int index = node.mCachedAddressAfterUpdate; + + final int groupCount = node.mData.size(); + final int countSize = getGroupCountSize(node); + final int parentAddress = node.mCachedParentAddress; + if (1 == countSize) { + buffer[index++] = (byte)groupCount; + } else if (2 == countSize) { + // We need to signal 2-byte size by setting the top bit of the MSB to 1, so + // we | 0x80 to do this. + buffer[index++] = (byte)((groupCount >> 8) | 0x80); + buffer[index++] = (byte)(groupCount & 0xFF); + } else { + throw new RuntimeException("Strange size from getGroupCountSize : " + countSize); + } + int groupAddress = index; + for (int i = 0; i < groupCount; ++i) { + final CharGroup group = node.mData.get(i); + if (index != group.mCachedAddressAfterUpdate) { + throw new RuntimeException("Bug: write index is not the same as the cached address " + + "of the group : " + index + " <> " + group.mCachedAddressAfterUpdate); + } + groupAddress += getGroupHeaderSize(group, formatOptions); + // Sanity checks. + if (DBG && group.mFrequency > FormatSpec.MAX_TERMINAL_FREQUENCY) { + throw new RuntimeException("A node has a frequency > " + + FormatSpec.MAX_TERMINAL_FREQUENCY + + " : " + group.mFrequency); + } + if (group.mFrequency >= 0) groupAddress += FormatSpec.GROUP_FREQUENCY_SIZE; + final int childrenOffset = null == group.mChildren + ? FormatSpec.NO_CHILDREN_ADDRESS + : group.mChildren.mCachedAddressAfterUpdate - groupAddress; + buffer[index++] = + makeCharGroupFlags(group, groupAddress, childrenOffset, formatOptions); + + if (parentAddress == FormatSpec.NO_PARENT_ADDRESS) { + index = writeParentAddress(buffer, index, parentAddress, formatOptions); + } else { + index = writeParentAddress(buffer, index, parentAddress + + (node.mCachedAddressAfterUpdate - group.mCachedAddressAfterUpdate), + formatOptions); + } + + index = CharEncoding.writeCharArray(group.mChars, buffer, index); + if (group.hasSeveralChars()) { + buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR; + } + if (group.mFrequency >= 0) { + buffer[index++] = (byte) group.mFrequency; + } + + final int shift; + if (formatOptions.mSupportsDynamicUpdate) { + shift = writeVariableSignedAddress(buffer, index, childrenOffset); + } else { + shift = writeVariableAddress(buffer, index, childrenOffset); + } + index += shift; + groupAddress += shift; + + // Write shortcuts + if (null != group.mShortcutTargets) { + final int indexOfShortcutByteSize = index; + index += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE; + groupAddress += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE; + final Iterator<WeightedString> shortcutIterator = group.mShortcutTargets.iterator(); + while (shortcutIterator.hasNext()) { + final WeightedString target = shortcutIterator.next(); + ++groupAddress; + int shortcutFlags = makeShortcutFlags(shortcutIterator.hasNext(), + target.mFrequency); + buffer[index++] = (byte)shortcutFlags; + final int shortcutShift = CharEncoding.writeString(buffer, index, target.mWord); + index += shortcutShift; + groupAddress += shortcutShift; + } + final int shortcutByteSize = index - indexOfShortcutByteSize; + if (shortcutByteSize > 0xFFFF) { + throw new RuntimeException("Shortcut list too large"); + } + buffer[indexOfShortcutByteSize] = (byte)(shortcutByteSize >> 8); + buffer[indexOfShortcutByteSize + 1] = (byte)(shortcutByteSize & 0xFF); + } + // Write bigrams + if (null != group.mBigrams) { + final Iterator<WeightedString> bigramIterator = group.mBigrams.iterator(); + while (bigramIterator.hasNext()) { + final WeightedString bigram = bigramIterator.next(); + final CharGroup target = + FusionDictionary.findWordInTree(dict.mRoot, bigram.mWord); + final int addressOfBigram = target.mCachedAddressAfterUpdate; + final int unigramFrequencyForThisWord = target.mFrequency; + ++groupAddress; + final int offset = addressOfBigram - groupAddress; + int bigramFlags = makeBigramFlags(bigramIterator.hasNext(), offset, + bigram.mFrequency, unigramFrequencyForThisWord, bigram.mWord); + buffer[index++] = (byte)bigramFlags; + final int bigramShift = writeVariableAddress(buffer, index, Math.abs(offset)); + index += bigramShift; + groupAddress += bigramShift; + } + } + + } + if (formatOptions.mSupportsDynamicUpdate) { + buffer[index] = buffer[index + 1] = buffer[index + 2] + = FormatSpec.NO_FORWARD_LINK_ADDRESS; + index += FormatSpec.FORWARD_LINK_ADDRESS_SIZE; + } + if (index != node.mCachedAddressAfterUpdate + node.mCachedSize) throw new RuntimeException( + "Not the same size : written " + + (index - node.mCachedAddressAfterUpdate) + " bytes from a node that should have " + + node.mCachedSize + " bytes"); + return index; + } + + /** + * Dumps a collection of useful statistics about a node array. + * + * This prints purely informative stuff, like the total estimated file size, the + * number of nodes, of character groups, the repartition of each address size, etc + * + * @param nodes the node array. + */ + private static void showStatistics(ArrayList<Node> nodes) { + int firstTerminalAddress = Integer.MAX_VALUE; + int lastTerminalAddress = Integer.MIN_VALUE; + int size = 0; + int charGroups = 0; + int maxGroups = 0; + int maxRuns = 0; + for (final Node n : nodes) { + if (maxGroups < n.mData.size()) maxGroups = n.mData.size(); + for (final CharGroup cg : n.mData) { + ++charGroups; + if (cg.mChars.length > maxRuns) maxRuns = cg.mChars.length; + if (cg.mFrequency >= 0) { + if (n.mCachedAddressAfterUpdate < firstTerminalAddress) + firstTerminalAddress = n.mCachedAddressAfterUpdate; + if (n.mCachedAddressAfterUpdate > lastTerminalAddress) + lastTerminalAddress = n.mCachedAddressAfterUpdate; + } + } + if (n.mCachedAddressAfterUpdate + n.mCachedSize > size) { + size = n.mCachedAddressAfterUpdate + n.mCachedSize; + } + } + final int[] groupCounts = new int[maxGroups + 1]; + final int[] runCounts = new int[maxRuns + 1]; + for (final Node n : nodes) { + ++groupCounts[n.mData.size()]; + for (final CharGroup cg : n.mData) { + ++runCounts[cg.mChars.length]; + } + } + + MakedictLog.i("Statistics:\n" + + " total file size " + size + "\n" + + " " + nodes.size() + " nodes\n" + + " " + charGroups + " groups (" + ((float)charGroups / nodes.size()) + + " groups per node)\n" + + " first terminal at " + firstTerminalAddress + "\n" + + " last terminal at " + lastTerminalAddress + "\n" + + " Group stats : max = " + maxGroups); + for (int i = 0; i < groupCounts.length; ++i) { + MakedictLog.i(" " + i + " : " + groupCounts[i]); + } + MakedictLog.i(" Character run stats : max = " + maxRuns); + for (int i = 0; i < runCounts.length; ++i) { + MakedictLog.i(" " + i + " : " + runCounts[i]); + } + } + + /** + * Dumps a FusionDictionary to a file. + * + * This is the public entry point to write a dictionary to a file. + * + * @param destination the stream to write the binary data to. + * @param dict the dictionary to write. + * @param formatOptions file format options. + */ + public static void writeDictionaryBinary(final OutputStream destination, + final FusionDictionary dict, final FormatOptions formatOptions) + throws IOException, UnsupportedFormatException { + + // Addresses are limited to 3 bytes, but since addresses can be relative to each node, the + // structure itself is not limited to 16MB. However, if it is over 16MB deciding the order + // of the nodes becomes a quite complicated problem, because though the dictionary itself + // does not have a size limit, each node must still be within 16MB of all its children and + // parents. As long as this is ensured, the dictionary file may grow to any size. + + 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 + final int options = makeOptionsValue(dict, formatOptions); + 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(); + + // Leave the choice of the optimal node order to the flattenTree function. + MakedictLog.i("Flattening the tree..."); + ArrayList<Node> flatNodes = flattenTree(dict.mRoot); + + MakedictLog.i("Computing addresses..."); + computeAddresses(dict, flatNodes, formatOptions); + MakedictLog.i("Checking array..."); + if (DBG) checkFlatNodeArray(flatNodes); + + // Create a buffer that matches the final dictionary size. + final Node lastNode = flatNodes.get(flatNodes.size() - 1); + final int bufferSize = lastNode.mCachedAddressAfterUpdate + lastNode.mCachedSize; + final byte[] buffer = new byte[bufferSize]; + int index = 0; + + MakedictLog.i("Writing file..."); + int dataEndOffset = 0; + for (Node n : flatNodes) { + dataEndOffset = writePlacedNode(dict, buffer, n, formatOptions); + } + + if (DBG) showStatistics(flatNodes); + + destination.write(buffer, 0, dataEndOffset); + + destination.close(); + MakedictLog.i("Done"); + } +} |