/*
* JBoss, Home of Professional Open Source.
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership. Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
*
* 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 2.1 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA.
*/
package org.teiid.query.sql.lang;
import org.teiid.core.util.EquivalenceUtil;
import org.teiid.query.sql.*;
import org.teiid.query.sql.lang.PredicateCriteria.Negatable;
import org.teiid.query.sql.symbol.Expression;
/**
* Represents criteria such as: "<expression> IS NULL".
*/
public class IsNullCriteria extends PredicateCriteria implements Negatable {
private Expression expression;
/** Negation flag. Indicates whether the criteria expression contains a NOT. */
private boolean negated;
/**
* Constructs a default instance of this class.
*/
public IsNullCriteria() {}
/**
* Constructs an instance of this class with an expression
* @param expression The expression to be compared to null
*/
public IsNullCriteria( Expression expression ) {
this.expression = expression;
}
/**
* Set expression.
* @param expression Expression to compare to null
*/
public void setExpression(Expression expression) {
this.expression = expression;
}
/**
* Get expression.
* @return Expression to compare
*/
public Expression getExpression() {
return this.expression;
}
/**
* Returns whether this criteria is negated.
* @return flag indicating whether this criteria contains a NOT
*/
public boolean isNegated() {
return negated;
}
/**
* Sets the negation flag for this criteria.
* @param negationFlag true if this criteria contains a NOT; false otherwise
*/
public void setNegated(boolean negationFlag) {
negated = negationFlag;
}
@Override
public void negate() {
this.negated = !this.negated;
}
public void acceptVisitor(LanguageVisitor visitor) {
visitor.visit(this);
}
/**
* Get hash code. WARNING: The hash code is based on data in the criteria.
* If data values are changed, the hash code will change - don't hash this
* object and change values.
* @return Hash code for object
*/
public int hashCode() {
return (getExpression() == null) ? 0 : getExpression().hashCode();
}
/**
* Comparees this criteria to another object for equality
* @param obj Other object
* @return True if objects are equal
*/
public boolean equals(Object obj) {
if(this == obj) {
return true;
}
if(! (obj instanceof IsNullCriteria)) {
return false;
}
IsNullCriteria other = (IsNullCriteria) obj;
if (isNegated() ^ other.isNegated()) {
return false;
}
return EquivalenceUtil.areEqual(getExpression(), other.getExpression());
}
/**
* Deep copy of object
* @return Deep copy of object
*/
public Object clone() {
Expression copy = null;
if(getExpression() != null) {
copy = (Expression) getExpression().clone();
}
IsNullCriteria criteriaCopy = new IsNullCriteria(copy);
criteriaCopy.setNegated(isNegated());
return criteriaCopy;
}
}