package it.unimi.dsi.mg4j.query.nodes;
/*
* MG4J: Managing Gigabytes for Java
*
* Copyright (C) 2007-2010 Sebastiano Vigna
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
*/
import it.unimi.dsi.lang.MutableString;
/** A node representing a difference of two queries.
*
* @author Sebastiano Vigna
*/
public class Difference implements Query {
/** The minuend query. */
public final Query minuend;
/** The subtrahend query. */
public final Query subtrahend;
/** A margin that will be added to the left of each interval. */
public final int leftMargin;
/** A margin that will be added to the right of each interval. */
public final int rightMargin;
public Difference( final Query minuend, final Query subtrahend ) {
this( minuend, subtrahend, 0, 0 );
}
public Difference( final Query minuend, final Query subtrahend, final int leftMargin, final int rightMargin ) {
this.minuend = minuend;
this.subtrahend = subtrahend;
this.leftMargin = leftMargin;
this.rightMargin = rightMargin;
}
public String toString() {
return new MutableString().append( '(' ).append( minuend ).append( leftMargin == 0 && rightMargin == 0 ? " - " : " - [[" + leftMargin + ":" + rightMargin + "]] " ).append( subtrahend ).append( ')' ).toString();
}
public <T> T accept( final QueryBuilderVisitor<T> visitor ) throws QueryBuilderVisitorException {
if ( ! visitor.visitPre( this ) ) return null;
final T[] result = visitor.newArray( 2 );
if ( ( result[ 0 ] = minuend.accept( visitor ) ) == null ) return null;
if ( ( result[ 1 ] = subtrahend.accept( visitor ) ) == null ) return null;
return visitor.visitPost( this, result );
}
public boolean equals( final Object o ) {
if ( ! ( o instanceof Difference ) ) return false;
final Difference d = (Difference)o;
return minuend.equals( d.minuend ) && subtrahend.equals( d.subtrahend ) && leftMargin == d.leftMargin && rightMargin == d.rightMargin;
}
public int hashCode() {
return minuend.hashCode() ^ ( subtrahend.hashCode() * 23 ) ^ leftMargin ^ ( rightMargin * 23 );
}
}