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// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// 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 jodd.util;
import java.util.Comparator;
import java.util.List;
/**
* Binary search wrapper over any type of user-defined collection.
* It provides a finder for given element, but also finder of first
* and last index in range of equal elements.
*/
public abstract class BinarySearch {
/**
* Creates binary search wrapper over a list of comparable elements.
*/
public static BinarySearch on(final List list) {
return new BinarySearch() {
@Override
@SuppressWarnings( {"unchecked"})
protected int compare(final int index, final T element) {
return list.get(index).compareTo(element);
}
@Override
protected int getLastIndex() {
return list.size() - 1;
}
};
}
/**
* Creates binary search wrapper over a list with given comparator.
*/
public static BinarySearch on(final List list, final Comparator comparator) {
return new BinarySearch() {
@Override
@SuppressWarnings( {"unchecked"})
protected int compare(final int index, final T element) {
return comparator.compare(list.get(index), element);
}
@Override
protected int getLastIndex() {
return list.size() - 1;
}
};
}
/**
* Creates binary search wrapper over an array.
*/
public static BinarySearch on(final T[] array) {
return new BinarySearch() {
@Override
@SuppressWarnings( {"unchecked"})
protected int compare(final int index, final T element) {
return array[index].compareTo(element);
}
@Override
protected int getLastIndex() {
return array.length - 1;
}
};
}
/**
* Creates binary search wrapper over an array with given comparator.
*/
public static BinarySearch on(final T[] array, final Comparator comparator) {
return new BinarySearch() {
@Override
@SuppressWarnings( {"unchecked"})
protected int compare(final int index, final T element) {
return comparator.compare(array[index], element);
}
@Override
protected int getLastIndex() {
return array.length - 1;
}
};
}
// ---------------------------------------------------------------- abstract
/**
* Compares element at index position with given object.
*/
protected abstract int compare(int index, E element);
/**
* Returns index of last element in wrapped collection.
*/
protected abstract int getLastIndex();
// ---------------------------------------------------------------- find
/**
* Finds index of given element or negative value if element is not found.
*/
public int find(final E element) {
return find(element, 0, getLastIndex());
}
/**
* Finds index of given element in inclusive index range. Returns negative
* value if element is not found.
*/
public int find(final E element, int low, int high) {
while (low <= high) {
final int mid = (low + high) >>> 1;
final int delta = compare(mid, element);
if (delta < 0) {
low = mid + 1;
} else if (delta > 0) {
high = mid - 1;
} else {
return mid;
}
}
// not found
return -(low + 1);
}
// ---------------------------------------------------------------- first
/**
* Finds very first index of given element or negative value if element is not found.
*/
public int findFirst(final E o) {
return findFirst(o, 0, getLastIndex());
}
/**
* Finds very first index of given element in inclusive index range. Returns negative
* value if element is not found.
*/
public int findFirst(final E o, int low, int high) {
int ndx = -1;
while (low <= high) {
final int mid = (low + high) >>> 1;
final int delta = compare(mid, o);
if (delta < 0) {
low = mid + 1;
} else {
if (delta == 0) {
ndx = mid;
}
high = mid - 1;
}
}
if (ndx == -1) {
return -(low + 1);
}
return ndx;
}
// ---------------------------------------------------------------- last
/**
* Finds very last index of given element or negative value if element is not found.
*/
public int findLast(final E o) {
return findLast(o, 0, getLastIndex());
}
/**
* Finds very last index of given element in inclusive index range. Returns negative
* value if element is not found.
*/
public int findLast(final E o, int low, int high) {
int ndx = -1;
while (low <= high) {
final int mid = (low + high) >>> 1;
final int delta = compare(mid, o);
if (delta > 0) {
high = mid - 1;
} else {
if (delta == 0) {
ndx = mid;
}
low = mid + 1;
}
}
if (ndx == -1) {
return -(low + 1);
}
return ndx;
}
}
