/*
* Copyright (C) 2011 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 org.kelar.inputmethod.latin.makedict;
import org.kelar.inputmethod.annotations.UsedForTesting;
import org.kelar.inputmethod.latin.define.DecoderSpecificConstants;
import org.kelar.inputmethod.latin.makedict.FormatSpec.DictionaryOptions;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
/**
* A dictionary that can fusion heads and tails of words for more compression.
*/
@UsedForTesting
public final class FusionDictionary implements Iterable<WordProperty> {
private static final boolean DBG = MakedictLog.DBG;
private static int CHARACTER_NOT_FOUND_INDEX = -1;
/**
* A node array of the dictionary, containing several PtNodes.
*
* A PtNodeArray is but an ordered array of PtNodes, which essentially contain all the
* real information.
* This class also contains fields to cache size and address, to help with binary
* generation.
*/
public static final class PtNodeArray {
ArrayList<PtNode> mData;
// To help with binary generation
int mCachedSize = Integer.MIN_VALUE;
// mCachedAddressBefore/AfterUpdate are helpers for binary dictionary generation. They
// always hold the same value except between dictionary address compression, during which
// the update process needs to know about both values at the same time. Updating will
// update the AfterUpdate value, and the code will move them to BeforeUpdate before
// the next update pass.
int mCachedAddressBeforeUpdate = Integer.MIN_VALUE;
int mCachedAddressAfterUpdate = Integer.MIN_VALUE;
int mCachedParentAddress = 0;
public PtNodeArray() {
mData = new ArrayList<>();
}
public PtNodeArray(ArrayList<PtNode> data) {
Collections.sort(data, PTNODE_COMPARATOR);
mData = data;
}
}
/**
* PtNode is a group of characters, with probability information, shortcut targets, bigrams,
* and children (Pt means Patricia Trie).
*
* This is the central class of the in-memory representation. A PtNode is what can
* be seen as a traditional "trie node", except it can hold several characters at the
* same time. A PtNode essentially represents one or several characters in the middle
* of the trie tree; as such, it can be a terminal, and it can have children.
* In this in-memory representation, whether the PtNode is a terminal or not is represented
* by mProbabilityInfo. The PtNode is a terminal when the mProbabilityInfo is not null and the
* PtNode is not a terminal when the mProbabilityInfo is null. A terminal may have non-null
* shortcuts and/or bigrams, but a non-terminal may not. Moreover, children, if present,
* are non-null.
*/
public static final class PtNode {
private static final int NOT_A_TERMINAL = -1;
final int mChars[];
ArrayList<WeightedString> mBigrams;
// null == mProbabilityInfo indicates this is not a terminal.
ProbabilityInfo mProbabilityInfo;
int mTerminalId; // NOT_A_TERMINAL == mTerminalId indicates this is not a terminal.
PtNodeArray mChildren;
boolean mIsNotAWord; // Only a shortcut
boolean mIsPossiblyOffensive;
// mCachedSize and mCachedAddressBefore/AfterUpdate are helpers for binary dictionary
// generation. Before and After always hold the same value except during dictionary
// address compression, where the update process needs to know about both values at the
// same time. Updating will update the AfterUpdate value, and the code will move them
// to BeforeUpdate before the next update pass.
// The update process does not need two versions of mCachedSize.
int mCachedSize; // The size, in bytes, of this PtNode.
int mCachedAddressBeforeUpdate; // The address of this PtNode (before update)
int mCachedAddressAfterUpdate; // The address of this PtNode (after update)
public PtNode(final int[] chars, final ArrayList<WeightedString> bigrams,
final ProbabilityInfo probabilityInfo, final boolean isNotAWord,
final boolean isPossiblyOffensive) {
mChars = chars;
mProbabilityInfo = probabilityInfo;
mTerminalId = probabilityInfo == null ? NOT_A_TERMINAL : probabilityInfo.mProbability;
mBigrams = bigrams;
mChildren = null;
mIsNotAWord = isNotAWord;
mIsPossiblyOffensive = isPossiblyOffensive;
}
public PtNode(final int[] chars, final ArrayList<WeightedString> bigrams,
final ProbabilityInfo probabilityInfo, final boolean isNotAWord,
final boolean isPossiblyOffensive, final PtNodeArray children) {
mChars = chars;
mProbabilityInfo = probabilityInfo;
mBigrams = bigrams;
mChildren = children;
mIsNotAWord = isNotAWord;
mIsPossiblyOffensive = isPossiblyOffensive;
}
public void addChild(PtNode n) {
if (null == mChildren) {
mChildren = new PtNodeArray();
}
mChildren.mData.add(n);
}
public int getTerminalId() {
return mTerminalId;
}
public boolean isTerminal() {
return mProbabilityInfo != null;
}
public int getProbability() {
return isTerminal() ? mProbabilityInfo.mProbability : NOT_A_TERMINAL;
}
public boolean getIsNotAWord() {
return mIsNotAWord;
}
public boolean getIsPossiblyOffensive() {
return mIsPossiblyOffensive;
}
public ArrayList<WeightedString> getBigrams() {
// We don't want write permission to escape outside the package, so we return a copy
if (null == mBigrams) return null;
final ArrayList<WeightedString> copyOfBigrams = new ArrayList<>(mBigrams);
return copyOfBigrams;
}
public boolean hasSeveralChars() {
assert(mChars.length > 0);
return 1 < mChars.length;
}
/**
* Adds a word to the bigram list. Updates the probability information if the word already
* exists.
*/
public void addBigram(final String word, final ProbabilityInfo probabilityInfo) {
if (mBigrams == null) {
mBigrams = new ArrayList<>();
}
WeightedString bigram = getBigram(word);
if (bigram != null) {
bigram.mProbabilityInfo = probabilityInfo;
} else {
bigram = new WeightedString(word, probabilityInfo);
mBigrams.add(bigram);
}
}
/**
* Gets the bigram for the given word.
* Returns null if the word is not in the bigrams list.
*/
public WeightedString getBigram(final String word) {
// TODO: Don't do a linear search
if (mBigrams != null) {
final int size = mBigrams.size();
for (int i = 0; i < size; ++i) {
WeightedString bigram = mBigrams.get(i);
if (bigram.mWord.equals(word)) {
return bigram;
}
}
}
return null;
}
/**
* Updates the PtNode with the given properties. Adds the shortcut and bigram lists to
* the existing ones if any. Note: unigram, bigram, and shortcut frequencies are only
* updated if they are higher than the existing ones.
*/
void update(final ProbabilityInfo probabilityInfo,
final ArrayList<WeightedString> bigrams,
final boolean isNotAWord, final boolean isPossiblyOffensive) {
mProbabilityInfo = ProbabilityInfo.max(mProbabilityInfo, probabilityInfo);
if (bigrams != null) {
if (mBigrams == null) {
mBigrams = bigrams;
} else {
final int size = bigrams.size();
for (int i = 0; i < size; ++i) {
final WeightedString bigram = bigrams.get(i);
final WeightedString existingBigram = getBigram(bigram.mWord);
if (existingBigram == null) {
mBigrams.add(bigram);
} else {
existingBigram.mProbabilityInfo = ProbabilityInfo.max(
existingBigram.mProbabilityInfo, bigram.mProbabilityInfo);
}
}
}
}
mIsNotAWord = isNotAWord;
mIsPossiblyOffensive = isPossiblyOffensive;
}
}
public final DictionaryOptions mOptions;
public final PtNodeArray mRootNodeArray;
public FusionDictionary(final PtNodeArray rootNodeArray, final DictionaryOptions options) {
mRootNodeArray = rootNodeArray;
mOptions = options;
}
public void addOptionAttribute(final String key, final String value) {
mOptions.mAttributes.put(key, value);
}
/**
* Helper method to convert a String to an int array.
*/
static int[] getCodePoints(final String word) {
// TODO: this is a copy-paste of the old contents of StringUtils.toCodePointArray,
// which is not visible from the makedict package. Factor this code.
final int length = word.length();
if (length <= 0) return new int[] {};
final char[] characters = word.toCharArray();
final int[] codePoints = new int[Character.codePointCount(characters, 0, length)];
int codePoint = Character.codePointAt(characters, 0);
int dsti = 0;
for (int srci = Character.charCount(codePoint);
srci < length; srci += Character.charCount(codePoint), ++dsti) {
codePoints[dsti] = codePoint;
codePoint = Character.codePointAt(characters, srci);
}
codePoints[dsti] = codePoint;
return codePoints;
}
/**
* Helper method to add a word as a string.
*
* This method adds a word to the dictionary with the given frequency. Optional
* lists of bigrams can be passed here. For each word inside,
* they will be added to the dictionary as necessary.
* @param word the word to add.
* @param probabilityInfo probability information of the word.
* @param isNotAWord true if this should not be considered a word (e.g. shortcut only)
* @param isPossiblyOffensive true if this word is possibly offensive
*/
public void add(final String word, final ProbabilityInfo probabilityInfo,
final boolean isNotAWord, final boolean isPossiblyOffensive) {
add(getCodePoints(word), probabilityInfo, isNotAWord, isPossiblyOffensive);
}
/**
* Validity check for a PtNode array.
*
* This method checks that all PtNodes in a node array are ordered as expected.
* If they are, nothing happens. If they aren't, an exception is thrown.
*/
private static void checkStack(PtNodeArray ptNodeArray) {
ArrayList<PtNode> stack = ptNodeArray.mData;
int lastValue = -1;
for (int i = 0; i < stack.size(); ++i) {
int currentValue = stack.get(i).mChars[0];
if (currentValue <= lastValue) {
throw new RuntimeException("Invalid stack");
}
lastValue = currentValue;
}
}
/**
* Helper method to add a new bigram to the dictionary.
*
* @param word0 the previous word of the context
* @param word1 the next word of the context
* @param probabilityInfo the bigram probability info
*/
public void setBigram(final String word0, final String word1,
final ProbabilityInfo probabilityInfo) {
PtNode ptNode0 = findWordInTree(mRootNodeArray, word0);
if (ptNode0 != null) {
final PtNode ptNode1 = findWordInTree(mRootNodeArray, word1);
if (ptNode1 == null) {
add(getCodePoints(word1), new ProbabilityInfo(0), false /* isNotAWord */,
false /* isPossiblyOffensive */);
// The PtNode for the first word may have moved by the above insertion,
// if word1 and word2 share a common stem that happens not to have been
// a cutting point until now. In this case, we need to refresh ptNode.
ptNode0 = findWordInTree(mRootNodeArray, word0);
}
ptNode0.addBigram(word1, probabilityInfo);
} else {
throw new RuntimeException("First word of bigram not found " + word0);
}
}
/**
* Add a word to this dictionary.
*
* The shortcuts, if any, have to be in the dictionary already. If they aren't,
* an exception is thrown.
* @param word the word, as an int array.
* @param probabilityInfo the probability information of the word.
* @param isNotAWord true if this is not a word for spellchecking purposes (shortcut only or so)
* @param isPossiblyOffensive true if this word is possibly offensive
*/
private void add(final int[] word, final ProbabilityInfo probabilityInfo,
final boolean isNotAWord, final boolean isPossiblyOffensive) {
assert(probabilityInfo.mProbability <= FormatSpec.MAX_TERMINAL_FREQUENCY);
if (word.length >= DecoderSpecificConstants.DICTIONARY_MAX_WORD_LENGTH) {
MakedictLog.w("Ignoring a word that is too long: word.length = " + word.length);
return;
}
PtNodeArray currentNodeArray = mRootNodeArray;
int charIndex = 0;
PtNode currentPtNode = null;
int differentCharIndex = 0; // Set by the loop to the index of the char that differs
int nodeIndex = findIndexOfChar(mRootNodeArray, word[charIndex]);
while (CHARACTER_NOT_FOUND_INDEX != nodeIndex) {
currentPtNode = currentNodeArray.mData.get(nodeIndex);
differentCharIndex = compareCharArrays(currentPtNode.mChars, word, charIndex);
if (ARRAYS_ARE_EQUAL != differentCharIndex
&& differentCharIndex < currentPtNode.mChars.length) break;
if (null == currentPtNode.mChildren) break;
charIndex += currentPtNode.mChars.length;
if (charIndex >= word.length) break;
currentNodeArray = currentPtNode.mChildren;
nodeIndex = findIndexOfChar(currentNodeArray, word[charIndex]);
}
if (CHARACTER_NOT_FOUND_INDEX == nodeIndex) {
// No node at this point to accept the word. Create one.
final int insertionIndex = findInsertionIndex(currentNodeArray, word[charIndex]);
final PtNode newPtNode = new PtNode(Arrays.copyOfRange(word, charIndex, word.length),
null /* bigrams */, probabilityInfo, isNotAWord,
isPossiblyOffensive);
currentNodeArray.mData.add(insertionIndex, newPtNode);
if (DBG) checkStack(currentNodeArray);
} else {
// There is a word with a common prefix.
if (differentCharIndex == currentPtNode.mChars.length) {
if (charIndex + differentCharIndex >= word.length) {
// The new word is a prefix of an existing word, but the node on which it
// should end already exists as is. Since the old PtNode was not a terminal,
// make it one by filling in its frequency and other attributes
currentPtNode.update(probabilityInfo, null, isNotAWord,
isPossiblyOffensive);
} else {
// The new word matches the full old word and extends past it.
// We only have to create a new node and add it to the end of this.
final PtNode newNode = new PtNode(
Arrays.copyOfRange(word, charIndex + differentCharIndex, word.length),
null /* bigrams */, probabilityInfo,
isNotAWord, isPossiblyOffensive);
currentPtNode.mChildren = new PtNodeArray();
currentPtNode.mChildren.mData.add(newNode);
}
} else {
if (0 == differentCharIndex) {
// Exact same word. Update the frequency if higher. This will also add the
// new shortcuts to the existing shortcut list if it already exists.
currentPtNode.update(probabilityInfo, null,
currentPtNode.mIsNotAWord && isNotAWord,
currentPtNode.mIsPossiblyOffensive || isPossiblyOffensive);
} else {
// Partial prefix match only. We have to replace the current node with a node
// containing the current prefix and create two new ones for the tails.
PtNodeArray newChildren = new PtNodeArray();
final PtNode newOldWord = new PtNode(
Arrays.copyOfRange(currentPtNode.mChars, differentCharIndex,
currentPtNode.mChars.length),
currentPtNode.mBigrams, currentPtNode.mProbabilityInfo,
currentPtNode.mIsNotAWord, currentPtNode.mIsPossiblyOffensive,
currentPtNode.mChildren);
newChildren.mData.add(newOldWord);
final PtNode newParent;
if (charIndex + differentCharIndex >= word.length) {
newParent = new PtNode(
Arrays.copyOfRange(currentPtNode.mChars, 0, differentCharIndex),
null /* bigrams */, probabilityInfo,
isNotAWord, isPossiblyOffensive, newChildren);
} else {
newParent = new PtNode(
Arrays.copyOfRange(currentPtNode.mChars, 0, differentCharIndex),
null /* bigrams */, null /* probabilityInfo */,
false /* isNotAWord */, false /* isPossiblyOffensive */,
newChildren);
final PtNode newWord = new PtNode(Arrays.copyOfRange(word,
charIndex + differentCharIndex, word.length),
null /* bigrams */, probabilityInfo,
isNotAWord, isPossiblyOffensive);
final int addIndex = word[charIndex + differentCharIndex]
> currentPtNode.mChars[differentCharIndex] ? 1 : 0;
newChildren.mData.add(addIndex, newWord);
}
currentNodeArray.mData.set(nodeIndex, newParent);
}
if (DBG) checkStack(currentNodeArray);
}
}
}
private static int ARRAYS_ARE_EQUAL = 0;
/**
* Custom comparison of two int arrays taken to contain character codes.
*
* This method compares the two arrays passed as an argument in a lexicographic way,
* with an offset in the dst string.
* This method does NOT test for the first character. It is taken to be equal.
* I repeat: this method starts the comparison at 1 <> dstOffset + 1.
* The index where the strings differ is returned. ARRAYS_ARE_EQUAL = 0 is returned if the
* strings are equal. This works BECAUSE we don't look at the first character.
*
* @param src the left-hand side string of the comparison.
* @param dst the right-hand side string of the comparison.
* @param dstOffset the offset in the right-hand side string.
* @return the index at which the strings differ, or ARRAYS_ARE_EQUAL = 0 if they don't.
*/
private static int compareCharArrays(final int[] src, final int[] dst, int dstOffset) {
// We do NOT test the first char, because we come from a method that already
// tested it.
for (int i = 1; i < src.length; ++i) {
if (dstOffset + i >= dst.length) return i;
if (src[i] != dst[dstOffset + i]) return i;
}
if (dst.length > src.length) return src.length;
return ARRAYS_ARE_EQUAL;
}
/**
* Helper class that compares and sorts two PtNodes according to their
* first element only. I repeat: ONLY the first element is considered, the rest
* is ignored.
* This comparator imposes orderings that are inconsistent with equals.
*/
static final class PtNodeComparator implements java.util.Comparator<PtNode> {
@Override
public int compare(PtNode p1, PtNode p2) {
if (p1.mChars[0] == p2.mChars[0]) return 0;
return p1.mChars[0] < p2.mChars[0] ? -1 : 1;
}
}
final static PtNodeComparator PTNODE_COMPARATOR = new PtNodeComparator();
/**
* Finds the insertion index of a character within a node array.
*/
private static int findInsertionIndex(final PtNodeArray nodeArray, int character) {
final ArrayList<PtNode> data = nodeArray.mData;
final PtNode reference = new PtNode(new int[] { character },
null /* bigrams */, null /* probabilityInfo */,
false /* isNotAWord */, false /* isPossiblyOffensive */);
int result = Collections.binarySearch(data, reference, PTNODE_COMPARATOR);
return result >= 0 ? result : -result - 1;
}
/**
* Find the index of a char in a node array, if it exists.
*
* @param nodeArray the node array to search in.
* @param character the character to search for.
* @return the position of the character if it's there, or CHARACTER_NOT_FOUND_INDEX = -1 else.
*/
private static int findIndexOfChar(final PtNodeArray nodeArray, int character) {
final int insertionIndex = findInsertionIndex(nodeArray, character);
if (nodeArray.mData.size() <= insertionIndex) return CHARACTER_NOT_FOUND_INDEX;
return character == nodeArray.mData.get(insertionIndex).mChars[0] ? insertionIndex
: CHARACTER_NOT_FOUND_INDEX;
}
/**
* Helper method to find a word in a given branch.
*/
public static PtNode findWordInTree(final PtNodeArray rootNodeArray, final String string) {
PtNodeArray nodeArray = rootNodeArray;
int index = 0;
final StringBuilder checker = DBG ? new StringBuilder() : null;
final int[] codePoints = getCodePoints(string);
PtNode currentPtNode;
do {
int indexOfGroup = findIndexOfChar(nodeArray, codePoints[index]);
if (CHARACTER_NOT_FOUND_INDEX == indexOfGroup) return null;
currentPtNode = nodeArray.mData.get(indexOfGroup);
if (codePoints.length - index < currentPtNode.mChars.length) return null;
int newIndex = index;
while (newIndex < codePoints.length && newIndex - index < currentPtNode.mChars.length) {
if (currentPtNode.mChars[newIndex - index] != codePoints[newIndex]) return null;
newIndex++;
}
index = newIndex;
if (DBG) {
checker.append(new String(currentPtNode.mChars, 0, currentPtNode.mChars.length));
}
if (index < codePoints.length) {
nodeArray = currentPtNode.mChildren;
}
} while (null != nodeArray && index < codePoints.length);
if (index < codePoints.length) return null;
if (!currentPtNode.isTerminal()) return null;
if (DBG && !string.equals(checker.toString())) return null;
return currentPtNode;
}
/**
* Helper method to find out whether a word is in the dict or not.
*/
public boolean hasWord(final String s) {
if (null == s || "".equals(s)) {
throw new RuntimeException("Can't search for a null or empty string");
}
return null != findWordInTree(mRootNodeArray, s);
}
/**
* Recursively count the number of PtNodes in a given branch of the trie.
*
* @param nodeArray the parent node.
* @return the number of PtNodes in all the branch under this node.
*/
public static int countPtNodes(final PtNodeArray nodeArray) {
final int nodeSize = nodeArray.mData.size();
int size = nodeSize;
for (int i = nodeSize - 1; i >= 0; --i) {
PtNode ptNode = nodeArray.mData.get(i);
if (null != ptNode.mChildren)
size += countPtNodes(ptNode.mChildren);
}
return size;
}
/**
* Iterator to walk through a dictionary.
*
* This is purely for convenience.
*/
public static final class DictionaryIterator implements Iterator<WordProperty> {
private static final class Position {
public Iterator<PtNode> pos;
public int length;
public Position(ArrayList<PtNode> ptNodes) {
pos = ptNodes.iterator();
length = 0;
}
}
final StringBuilder mCurrentString;
final LinkedList<Position> mPositions;
public DictionaryIterator(ArrayList<PtNode> ptRoot) {
mCurrentString = new StringBuilder();
mPositions = new LinkedList<>();
final Position rootPos = new Position(ptRoot);
mPositions.add(rootPos);
}
@Override
public boolean hasNext() {
for (Position p : mPositions) {
if (p.pos.hasNext()) {
return true;
}
}
return false;
}
@Override
public WordProperty next() {
Position currentPos = mPositions.getLast();
mCurrentString.setLength(currentPos.length);
do {
if (currentPos.pos.hasNext()) {
final PtNode currentPtNode = currentPos.pos.next();
currentPos.length = mCurrentString.length();
for (int i : currentPtNode.mChars) {
mCurrentString.append(Character.toChars(i));
}
if (null != currentPtNode.mChildren) {
currentPos = new Position(currentPtNode.mChildren.mData);
currentPos.length = mCurrentString.length();
mPositions.addLast(currentPos);
}
if (currentPtNode.isTerminal()) {
return new WordProperty(mCurrentString.toString(),
currentPtNode.mProbabilityInfo, currentPtNode.mBigrams,
currentPtNode.mIsNotAWord, currentPtNode.mIsPossiblyOffensive);
}
} else {
mPositions.removeLast();
currentPos = mPositions.getLast();
mCurrentString.setLength(mPositions.getLast().length);
}
} while (true);
}
@Override
public void remove() {
throw new UnsupportedOperationException("Unsupported yet");
}
}
/**
* Method to return an iterator.
*
* This method enables Java's enhanced for loop. With this you can have a FusionDictionary x
* and say : for (Word w : x) {}
*/
@Override
public Iterator<WordProperty> iterator() {
return new DictionaryIterator(mRootNodeArray.mData);
}
}
