code: /*
   * Copyright (c) 2017-2018 The Regents of the University of California
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   *
   * 1. Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package edu.berkeley.cs.jqf.fuzz.util;
  
  import org.eclipse.collections.api.iterator.IntIterator;
  import org.eclipse.collections.api.list.primitive.IntList;
  import org.eclipse.collections.impl.list.mutable.primitive.IntArrayList;
  
  
  /**
   * An extension of {@link Counter} that caches which entries
   * are non-zero.
   *
   * <p>This version of counter is used by classes such as
   * {@link Coverage}, which require frequent queries of
   * the non-zero locations.</p>
   */
  public class NonZeroCachingCounter extends Counter {
  
      private int nonZeroCount;
  
      private IntArrayList nonZeroIndices;
  
      public NonZeroCachingCounter(int size) {
          super(size);
          this.nonZeroCount = 0;
          this.nonZeroIndices = new IntArrayList();
      }
  
      @Override
      public void clear() {
          IntIterator iter = nonZeroIndices.intIterator();
          while(iter.hasNext()){
              int idx = iter.next();
              counts[idx] = 0;
          }
          this.nonZeroCount = 0;
          this.nonZeroIndices = new IntArrayList();
      }
  
  
      @Override
      public int incrementAtIndex(int index, int delta) {
          int newValue = super.incrementAtIndex(index, delta);
          // A count becomes non-zero if it was incremented to delta
          if (newValue == delta) {
              nonZeroIndices.add(index);
              nonZeroCount++;
          }
          return newValue;
      }
  
      @Override
      public int getNonZeroSize() {
          return nonZeroCount;
      }
  
      @Override
      public boolean hasNonZeros(){
          return nonZeroCount > 0;
      }
  
      @Override
      public IntList getNonZeroIndices() {
          return nonZeroIndices;
      }
  
      @Override
      public IntList getNonZeroValues() {
          IntArrayList values = new IntArrayList(this.size / 2);
          IntIterator iter = nonZeroIndices.intIterator();
          while(iter.hasNext()){
              int idx = iter.next();
              int count = counts[idx];
              assert (count != 0);
              values.add(count);
          }
          return values;
      }
  
      @Override
      public void setAtIndex(int index, int newValue) {
          int oldValue = counts[index];
          super.setAtIndex(index, newValue);
          if (oldValue == 0 && newValue != 0) {
              nonZeroIndices.add(index);
              nonZeroCount++;
          }
      }
  
  
  }
  