com.googlecode.javaewah.IteratingBufferedRunningLengthWord Maven / Gradle / Ivy
package com.googlecode.javaewah;
/*
* Copyright 2009-2013, Daniel Lemire, Cliff Moon, David McIntosh, Robert Becho, Google Inc., Veronika Zenz and Owen Kaser
* Licensed under the Apache License, Version 2.0.
*/
/**
* Mostly for internal use. Similar to BufferedRunningLengthWord, but automatically
* advances to the next BufferedRunningLengthWord as words are discarded.
*
* @since 0.4.0
* @author David McIntosh
*/
public final class IteratingBufferedRunningLengthWord implements IteratingRLW, Cloneable{
/**
* Instantiates a new iterating buffered running length word.
*
* @param iterator iterator
*/
public IteratingBufferedRunningLengthWord(final EWAHIterator iterator) {
this.iterator = iterator;
this.brlw = new BufferedRunningLengthWord(this.iterator.next());
this.literalWordStartPosition = this.iterator.literalWords() + this.brlw.literalwordoffset;
this.buffer = this.iterator.buffer();
}
/**
* Instantiates a new iterating buffered running length word.
* @param bitmap over which we want to iterate
*
*/
public IteratingBufferedRunningLengthWord(final EWAHCompressedBitmap bitmap) {
this.iterator = EWAHIterator.getEWAHIterator(bitmap);
this.brlw = new BufferedRunningLengthWord(this.iterator.next());
this.literalWordStartPosition = this.iterator.literalWords() + this.brlw.literalwordoffset;
this.buffer = this.iterator.buffer();
}
/**
* Discard first words, iterating to the next running length word if needed.
*
* @param x the number of words to be discarded
*/
@Override
public void discardFirstWords(long x) {
while (x > 0) {
if (this.brlw.RunningLength > x) {
this.brlw.RunningLength -= x;
return;
}
x -= this.brlw.RunningLength;
this.brlw.RunningLength = 0;
long toDiscard = x > this.brlw.NumberOfLiteralWords ? this.brlw.NumberOfLiteralWords : x;
this.literalWordStartPosition += toDiscard;
this.brlw.NumberOfLiteralWords -= toDiscard;
x -= toDiscard;
if ((x > 0) || (this.brlw.size() == 0)) {
if (!this.iterator.hasNext()) {
break;
}
this.brlw.reset(this.iterator.next());
this.literalWordStartPosition = this.iterator.literalWords(); // + this.brlw.literalwordoffset ==0
}
}
}
/**
* Move to the next RunningLengthWord
* @return whether the move was possible
*/
@Override
public boolean next() {
if (!this.iterator.hasNext()) {
this.brlw.NumberOfLiteralWords = 0;
this.brlw.RunningLength = 0;
return false;
}
this.brlw.reset(this.iterator.next());
this.literalWordStartPosition = this.iterator.literalWords(); // + this.brlw.literalwordoffset ==0
return true;
}
/**
* Write out up to max words, returns how many were written
* @param container target for writes
* @param max maximal number of writes
* @return how many written
*/
public long discharge(BitmapStorage container, long max) {
long index = 0;
while ((index < max) && (size() > 0)) {
// first run
long pl = getRunningLength();
if (index + pl > max) {
pl = max - index;
}
container.addStreamOfEmptyWords(getRunningBit(), pl);
index += pl;
int pd = getNumberOfLiteralWords();
if (pd + index > max) {
pd = (int) (max - index);
}
writeLiteralWords(pd, container);
discardFirstWords(pl+pd);
index += pd;
}
return index;
}
/**
* Write out up to max words (negated), returns how many were written
* @param container target for writes
* @param max maximal number of writes
* @return how many written
*/
public long dischargeNegated(BitmapStorage container, long max) {
long index = 0;
while ((index < max) && (size() > 0)) {
// first run
long pl = getRunningLength();
if (index + pl > max) {
pl = max - index;
}
container.addStreamOfEmptyWords(!getRunningBit(), pl);
index += pl;
int pd = getNumberOfLiteralWords();
if (pd + index > max) {
pd = (int) (max - index);
}
writeNegatedLiteralWords(pd, container);
discardFirstWords(pl+pd);
index += pd;
}
return index;
}
/**
* Write out the remain words, transforming them to zeroes.
* @param container target for writes
*/
public void dischargeAsEmpty(BitmapStorage container) {
while(size()>0) {
container.addStreamOfEmptyWords(false, size());
discardFirstWords(size());
}
}
/**
* Write out the remaining words
* @param container target for writes
*/
public void discharge(BitmapStorage container) {
this.brlw.literalwordoffset = this.literalWordStartPosition - this.iterator.literalWords();
discharge(this.brlw, this.iterator, container);
}
/**
* Get the nth literal word for the current running length word
* @param index zero based index
* @return the literal word
*/
@Override
public long getLiteralWordAt(int index) {
return this.buffer[this.literalWordStartPosition + index];
}
/**
* Gets the number of literal words for the current running length word.
*
* @return the number of literal words
*/
@Override
public int getNumberOfLiteralWords() {
return this.brlw.NumberOfLiteralWords;
}
/**
* Gets the running bit.
*
* @return the running bit
*/
@Override
public boolean getRunningBit() {
return this.brlw.RunningBit;
}
/**
* Gets the running length.
*
* @return the running length
*/
@Override
public long getRunningLength() {
return this.brlw.RunningLength;
}
/**
* Size in uncompressed words of the current running length word.
*
* @return the long
*/
@Override
public long size() {
return this.brlw.size();
}
/**
* write the first N literal words to the target bitmap. Does not discard the words or perform iteration.
* @param numWords number of words to be written
* @param container where we write
*/
public void writeLiteralWords(int numWords, BitmapStorage container) {
container.addStreamOfLiteralWords(this.buffer, this.literalWordStartPosition, numWords);
}
/**
* write the first N literal words (negated) to the target bitmap. Does not discard the words or perform iteration.
* @param numWords number of words to be written
* @param container where we write
*/
public void writeNegatedLiteralWords(int numWords, BitmapStorage container) {
container.addStreamOfNegatedLiteralWords(this.buffer, this.literalWordStartPosition, numWords);
}
/**
* For internal use. (One could use the non-static discharge method instead,
* but we expect them to be slower.)
*
* @param initialWord
* the initial word
* @param iterator
* the iterator
* @param container
* the container
*/
private static void discharge(final BufferedRunningLengthWord initialWord,
final EWAHIterator iterator, final BitmapStorage container) {
BufferedRunningLengthWord runningLengthWord = initialWord;
for (;;) {
final long runningLength = runningLengthWord.getRunningLength();
container.addStreamOfEmptyWords(runningLengthWord.getRunningBit(),
runningLength);
container.addStreamOfLiteralWords(iterator.buffer(), iterator.literalWords()
+ runningLengthWord.literalwordoffset,
runningLengthWord.getNumberOfLiteralWords());
if (!iterator.hasNext())
break;
runningLengthWord = new BufferedRunningLengthWord(iterator.next());
}
}
@Override
public IteratingBufferedRunningLengthWord clone() throws CloneNotSupportedException {
IteratingBufferedRunningLengthWord answer = (IteratingBufferedRunningLengthWord) super.clone();
answer.brlw = this.brlw.clone();
answer.buffer = this.buffer;
answer.iterator = this.iterator.clone();
answer.literalWordStartPosition = this.literalWordStartPosition;
return answer;
}
private BufferedRunningLengthWord brlw;
private long[] buffer;
private int literalWordStartPosition;
private EWAHIterator iterator;
}
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