org.javimmutable.collections.cursors.Cursors Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of javimmutable-collections Show documentation
Show all versions of javimmutable-collections Show documentation
Library providing immutable/persistent collection classes for
Java. While collections are immutable they provide methods for
adding and removing values by creating new modified copies of
themselves. Each copy shares almost all of its structure with
other copies to minimize memory consumption.
///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2018, Burton Computer Corporation
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 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.
//
// Neither the name of the Burton Computer Corporation nor the names
// of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// 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 org.javimmutable.collections.cursors;
import org.javimmutable.collections.Cursor;
public final class Cursors
{
private Cursors()
{
}
/**
* Computes a hash code from the hash codes of all values in the cursor.
*
* @param cursor
* @return
*/
public static int computeHashCode(Cursor cursor)
{
int answer = 0;
for (cursor = cursor.start(); cursor.hasValue(); cursor = cursor.next()) {
Object value = cursor.getValue();
answer = 31 * answer + ((value != null) ? value.hashCode() : 0);
}
return answer;
}
/**
* Return true if and only if both cursors have the same length and contain objects
* that are equal based on their equals() methods.
*
* @param a
* @param b
* @return
*/
public static boolean areEqual(Cursor a,
Cursor b)
{
a = a.start();
b = b.start();
while (a.hasValue() && b.hasValue()) {
Object av = a.getValue();
Object bv = b.getValue();
if (av == null) {
if (bv != null) {
return false;
}
} else if (bv == null) {
return false;
} else if (!av.equals(bv)) {
return false;
}
a = a.next();
b = b.next();
}
return a.hasValue() == b.hasValue();
}
public static String makeString(Cursor cursor)
{
StringBuilder sb = new StringBuilder();
sb.append("[");
for (cursor = cursor.start(); cursor.hasValue(); cursor = cursor.next()) {
if (sb.length() > 1) {
sb.append(",");
}
Object value = cursor.getValue();
if (value == null) {
sb.append("null");
} else {
sb.append(value);
}
}
sb.append("]");
return sb.toString();
}
}