Copyright (c) 2000, 2011 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.compare.rangedifferencer;

Description of a change between two or three ranges of comparable entities.

RangeDifference objects are the elements of a compare result returned from
the RangeDifferencer find*  methods.
Clients use these objects as they are returned from the differencer.
This class is not intended to be instantiated outside of the Compare framework.

Note: A range in the RangeDifference object is given as a start index
and length in terms of comparable entities. However, these entity indices and counts
are not necessarily character positions. For example, if an entity represents a line
in a document, the start index would be a line number and the count would be in lines.

See Also:
RangeDifferencer
@noinstantiate
This class is not intended to be instantiated by clients./**
 * Description of a change between two or three ranges of comparable entities.
 * <p>
 * <code>RangeDifference</code> objects are the elements of a compare result returned from
 * the <code>RangeDifferencer</code> <code>find* </code> methods.
 * Clients use these objects as they are returned from the differencer.
 * This class is not intended to be instantiated outside of the Compare framework.
 * <p>
 * Note: A range in the <code>RangeDifference</code> object is given as a start index
 * and length in terms of comparable entities. However, these entity indices and counts
 * are not necessarily character positions. For example, if an entity represents a line
 * in a document, the start index would be a line number and the count would be in lines.
 * </p>
 *
 * @see RangeDifferencer
 * @noinstantiate This class is not intended to be instantiated by clients.
 */
public class RangeDifference {

	
Two-way change constant indicating no change. /** Two-way change constant indicating no change. */
	public final static int NOCHANGE = 0;

	
Two-way change constant indicating two-way change (same as
RIGHT)
/**
	 * Two-way change constant indicating two-way change (same as
	 * <code>RIGHT</code>)
	 */
	public final static int CHANGE = 2;

	
Three-way change constant indicating a change in both right and left. /** Three-way change constant indicating a change in both right and left. */
	public final static int CONFLICT = 1;

	
Three-way change constant indicating a change in right. /** Three-way change constant indicating a change in right. */
	public final static int RIGHT = 2;

	
Three-way change constant indicating a change in left. /** Three-way change constant indicating a change in left. */
	public final static int LEFT = 3;

	
Three-way change constant indicating the same change in both right and
left, that is only the ancestor is different.
/**
	 * Three-way change constant indicating the same change in both right and
	 * left, that is only the ancestor is different.
	 */
	public final static int ANCESTOR = 4;

	
Constant indicating an unknown change kind. /** Constant indicating an unknown change kind. */
	public final static int ERROR = 5;

	
the kind of change: NOCHANGE, CHANGE, LEFT, RIGHT, ANCESTOR, CONFLICT,
ERROR
Since:
org.eclipse.compare.core 3.5/**
	 * the kind of change: NOCHANGE, CHANGE, LEFT, RIGHT, ANCESTOR, CONFLICT,
	 * ERROR
	 *
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int kind;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int leftStart;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int leftLength;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int rightStart;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int rightLength;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int ancestorStart;

	
Since:
org.eclipse.compare.core 3.5/**
	 * @since org.eclipse.compare.core 3.5
	 */
	protected int ancestorLength;

	
Creates a new range difference with the given change kind.
Params:
changeKind – 
           the kind of change
Since:
org.eclipse.compare.core 3.5/**
	 * Creates a new range difference with the given change kind.
	 *
	 * @param changeKind
	 *            the kind of change
	 * @since org.eclipse.compare.core 3.5
	 */
	protected RangeDifference(int changeKind) {
		this.kind = changeKind;
	}

	
Creates a new RangeDifference with the given change kind and
left and right ranges.
Params:
kind – 
           the kind of change
rightStart – 
           start index of entity on right side
rightLength – 
           number of entities on right side
leftStart – 
           start index of entity on left side
leftLength – 
           number of entities on left side
Since:
org.eclipse.compare.core 3.5/**
	 * Creates a new <code>RangeDifference</code> with the given change kind and
	 * left and right ranges.
	 *
	 * @param kind
	 *            the kind of change
	 * @param rightStart
	 *            start index of entity on right side
	 * @param rightLength
	 *            number of entities on right side
	 * @param leftStart
	 *            start index of entity on left side
	 * @param leftLength
	 *            number of entities on left side
	 * @since org.eclipse.compare.core 3.5
	 */
	protected RangeDifference(int kind, int rightStart, int rightLength, int leftStart, int leftLength) {
		this.kind= kind;
		this.rightStart= rightStart;
		this.rightLength= rightLength;
		this.leftStart= leftStart;
		this.leftLength= leftLength;
	}

	
Creates a new RangeDifference with the given change kind and
left, right, and ancestor ranges.
Params:
kind – 
           the kind of change
rightStart – 
           start index of entity on right side
rightLength – 
           number of entities on right side
leftStart – 
           start index of entity on left side
leftLength – 
           number of entities on left side
ancestorStart – 
           start index of entity on ancestor side
ancestorLength – 
           number of entities on ancestor side
Since:
org.eclipse.compare.core 3.5/**
	 * Creates a new <code>RangeDifference</code> with the given change kind and
	 * left, right, and ancestor ranges.
	 *
	 * @param kind
	 *            the kind of change
	 * @param rightStart
	 *            start index of entity on right side
	 * @param rightLength
	 *            number of entities on right side
	 * @param leftStart
	 *            start index of entity on left side
	 * @param leftLength
	 *            number of entities on left side
	 * @param ancestorStart
	 *            start index of entity on ancestor side
	 * @param ancestorLength
	 *            number of entities on ancestor side
	 * @since org.eclipse.compare.core 3.5
	 */
	protected RangeDifference(int kind, int rightStart, int rightLength, int leftStart, int leftLength,
									int ancestorStart, int ancestorLength) {
		this(kind, rightStart, rightLength, leftStart, leftLength);
		this.ancestorStart= ancestorStart;
		this.ancestorLength= ancestorLength;
	}

	
Returns the kind of difference.
Returns:
the kind of difference, one of
NOCHANGE, CHANGE, LEFT, RIGHT,
ANCESTOR, CONFLICT, ERROR/**
	 * Returns the kind of difference.
	 *
	 * @return the kind of difference, one of
	 * <code>NOCHANGE</code>, <code>CHANGE</code>, <code>LEFT</code>, <code>RIGHT</code>,
	 * <code>ANCESTOR</code>, <code>CONFLICT</code>, <code>ERROR</code>
	 */
	public int kind() {
		return this.kind;
	}

	
Returns the start index of the entity range on the ancestor side.
Returns:
the start index of the entity range on the ancestor side/**
	 * Returns the start index of the entity range on the ancestor side.
	 *
	 * @return the start index of the entity range on the ancestor side
	 */
	public int ancestorStart() {
		return this.ancestorStart;
	}

	
Returns the number of entities on the ancestor side.
Returns:
the number of entities on the ancestor side/**
	 * Returns the number of entities on the ancestor side.
	 *
	 * @return the number of entities on the ancestor side
	 */
	public int ancestorLength() {
		return this.ancestorLength;
	}

	
Returns the end index of the entity range on the ancestor side.
Returns:
the end index of the entity range on the ancestor side/**
	 * Returns the end index of the entity range on the ancestor side.
	 *
	 * @return the end index of the entity range on the ancestor side
	 */
	public int ancestorEnd() {
		return this.ancestorStart + this.ancestorLength;
	}

	
Returns the start index of the entity range on the right side.
Returns:
the start index of the entity range on the right side/**
	 * Returns the start index of the entity range on the right side.
	 *
	 * @return the start index of the entity range on the right side
	 */
	public int rightStart() {
		return this.rightStart;
	}

	
Returns the number of entities on the right side.
Returns:
the number of entities on the right side/**
	 * Returns the number of entities on the right side.
	 *
	 * @return the number of entities on the right side
	 */
	public int rightLength() {
		return this.rightLength;
	}

	
Returns the end index of the entity range on the right side.
Returns:
the end index of the entity range on the right side/**
	 * Returns the end index of the entity range on the right side.
	 *
	 * @return the end index of the entity range on the right side
	 */
	public int rightEnd() {
		return this.rightStart + this.rightLength;
	}

	
Returns the start index of the entity range on the left side.
Returns:
the start index of the entity range on the left side/**
	 * Returns the start index of the entity range on the left side.
	 *
	 * @return the start index of the entity range on the left side
	 */
	public int leftStart() {
		return this.leftStart;
	}

	
Returns the number of entities on the left side.
Returns:
the number of entities on the left side/**
	 * Returns the number of entities on the left side.
	 *
	 * @return the number of entities on the left side
	 */
	public int leftLength() {
		return this.leftLength;
	}

	
Returns the end index of the entity range on the left side.
Returns:
the end index of the entity range on the left side/**
	 * Returns the end index of the entity range on the left side.
	 *
	 * @return the end index of the entity range on the left side
	 */
	public int leftEnd() {
		return this.leftStart + this.leftLength;
	}

	
Returns the maximum number of entities in the left, right, and ancestor sides of this range.
Returns:
the maximum number of entities in the left, right, and ancestor sides of this range/**
	 * Returns the maximum number of entities in the left, right, and ancestor sides of this range.
	 *
	 * @return the maximum number of entities in the left, right, and ancestor sides of this range
	 */
	public int maxLength() {
		return Math.max(this.rightLength, Math.max(this.leftLength, this.ancestorLength));
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof RangeDifference) {
			RangeDifference other = (RangeDifference) obj;
			return this.kind == other.kind
				&& this.leftStart == other.leftStart
				&& this.leftLength == other.leftLength
				&& this.rightStart == other.rightStart
				&& this.rightLength == other.rightLength
				&& this.ancestorStart == other.ancestorStart
				&& this.ancestorLength == other.ancestorLength;
		}
		return super.equals(obj);
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + this.kind;
		result = prime * result + this.leftStart;
		result = prime * result + this.leftLength;
		result = prime * result + this.rightStart;
		result = prime * result + this.rightLength;
		result = prime * result + this.ancestorStart;
		result = prime * result + this.ancestorLength;
		return result;
	}

	@Override
	public String toString() {
		StringBuilder buf = new StringBuilder("RangeDifference {"); //$NON-NLS-1$
		switch (this.kind) {
		case NOCHANGE:
			buf.append("NOCHANGE"); //$NON-NLS-1$
			break;
		case CHANGE:
			buf.append("CHANGE/RIGHT"); //$NON-NLS-1$
			break;
		case CONFLICT:
			buf.append("CONFLICT"); //$NON-NLS-1$
			break;
		case LEFT:
			buf.append("LEFT"); //$NON-NLS-1$
			break;
		case ERROR:
			buf.append("ERROR"); //$NON-NLS-1$
			break;
		case ANCESTOR:
			buf.append("ANCESTOR"); //$NON-NLS-1$
			break;
		default:
			break;
		}

		buf.append(", "); //$NON-NLS-1$

		buf.append("Left: " + toRangeString(this.leftStart, this.leftLength) + " Right: " + toRangeString(this.rightStart, this.rightLength)); //$NON-NLS-1$ //$NON-NLS-2$
		if (this.ancestorLength > 0 || this.ancestorStart > 0)
			buf.append(" Ancestor: " + toRangeString(this.ancestorStart, this.ancestorLength)); //$NON-NLS-1$

		buf.append("}"); //$NON-NLS-1$
		return buf.toString();
	}

	private String toRangeString(int start, int length) {
		return "(" + start + ", " + length + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	}
}