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package com.undefinedlabs.scope.deps.com.googlecode.javaewah;

import java.util.Iterator;

/*
 * 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.
 */

/**
 * Convenience functions for working over iterators
 *
 */
public class IteratorUtil {
	
	/**
	 * @param i iterator we wish to iterate over
	 * @return an iterator over the set bits corresponding to the iterator
	 */
	public static IntIterator toSetBitsIntIterator(final IteratingRLW i) {
		return new IntIteratorOverIteratingRLW(i);
	}

	/**
	 * @param i  iterator we wish to iterate over
	 * @return an iterator over the set bits corresponding to the iterator
	 */
	public static Iterator toSetBitsIterator(final IteratingRLW i) {
		return new Iterator() {
			@Override
			public boolean hasNext() {
				return this.under.hasNext();
			}

			@Override
			public Integer next() {
				return new Integer(this.under.next());
			}

			@Override
			public void remove() {
			}

			final private IntIterator under = toSetBitsIntIterator(i);
		};

	}

	/**
	 * Generate a bitmap from an iterator
	 * 
	 * @param i  iterator we wish to materialize
	 * @param c where we write
	 */
	public static void materialize(final IteratingRLW i, final BitmapStorage c) {
		while (true) {
			if (i.getRunningLength() > 0) {
				c.addStreamOfEmptyWords(i.getRunningBit(), i.getRunningLength());
			}
			for (int k = 0; k < i.getNumberOfLiteralWords(); ++k)
				c.add(i.getLiteralWordAt(k));
			if (!i.next())
				break;
		}
	}

	/**
	 * @param i iterator we wish to iterate over
	 * @return the cardinality (number of set bits) corresponding to the iterator
	 */
	public static int cardinality(final IteratingRLW i) {
		int answer = 0;
		while (true) {
			if(i.getRunningBit()) answer += i.getRunningLength() * EWAHCompressedBitmap.wordinbits;
			for (int k = 0; k < i.getNumberOfLiteralWords(); ++k)
				answer += Long.bitCount(i.getLiteralWordAt(k));
			if(!i.next()) break;
		}
		return answer;
	}
	
	/**
	 * @param x set of bitmaps
	 * @return an array of iterators corresponding to the array of bitmaps
	 */
	public static IteratingRLW[] toIterators(final EWAHCompressedBitmap... x) {
		IteratingRLW[] X = new IteratingRLW[x.length];
		for (int k = 0; k < X.length; ++k) {
			X[k] = new IteratingBufferedRunningLengthWord(x[k]);
		}
		return X;
	}
	/**
	 * Turn an iterator into a bitmap.
	 * 
	 * @param i iterator we wish to materialize
	 * @param c where we write
	 * @param Max maximum number of words we wish to materialize
	 * @return how many words were actually materialized
	 */
	public static long materialize(final IteratingRLW i, final BitmapStorage c, long Max) {
		final long origMax = Max;
		while (true) {
			if (i.getRunningLength() > 0) {
				long L = i.getRunningLength();
				if(L > Max) L = Max;
				c.addStreamOfEmptyWords(i.getRunningBit(), L);
				Max -= L;
			}
			long L = i.getNumberOfLiteralWords();
			for (int k = 0; k < L; ++k)
				c.add(i.getLiteralWordAt(k));
			if(Max>0)  {
				if (!i.next())
					break;
			}
				else break;
		}
		return origMax - Max;
	}
	/**
	 * Turn an iterator into a bitmap
	 * 
	 * @param i iterator we wish to materialize
	 * @return materialized version of the iterator
	 */
	public static EWAHCompressedBitmap materialize(final IteratingRLW i) {
		EWAHCompressedBitmap ewah = new EWAHCompressedBitmap();
		materialize(i, ewah);
		return ewah;
	}

}