/*
* 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.core.util.HashCodeUtil;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.symbol.Expression;
/**
* <p>A criteria which represents a simple operator relationship between two expressions.
* There are 6 operator types. Each side of the comparison may be an expression, which
* could be an element, a constant, or a function. </p>
*
* <p>Some examples are:</p>
* <UL>
* <LI>ticker = 'IBM'</LI>
* <li>price >= 50</LI>
* <LI>revenue < 0</LI>
* <LI>5 <= length(companyName)</LI>
* </UL>
*/
public class CompareCriteria extends AbstractCompareCriteria {
/** The right-hand expression. */
private Expression rightExpression;
//null means existing, but implied
//true means completely derived
//false means required
private Boolean isOptional = Boolean.FALSE;
/**
* Constructs a default instance of this class.
*/
public CompareCriteria() {
super();
}
/**
* Constructs an instance of this class for a specific "operand operator
* operand" clause.
*
* @param identifier The variable being compared
* @param value The value the variable is being compared to (literal or variable)
* @param operator The operator representing how the variable and value are to
* be compared
*/
public CompareCriteria( Expression leftExpression, int operator, Expression rightExpression ) {
super();
set(leftExpression, operator, rightExpression);
}
/**
* Set right expression.
* @param expression Right expression
*/
public void setRightExpression(Expression expression) {
this.rightExpression = expression;
}
/**
* Get right expression.
* @return right expression
*/
public Expression getRightExpression() {
return this.rightExpression;
}
/**
* Sets the operands and operator. The clause is of the form: <variable> <operator> <value>.
*
* @param leftExpression The left expression
* @param operator The operator representing how the expressions are compared
* @param rightExpression The right expression
*/
public void set( Expression leftExpression, int operator, Expression rightExpression ) {
setLeftExpression(leftExpression);
setOperator(operator);
setRightExpression(rightExpression);
}
/**
* Set during planning to indicate that this criteria is no longer needed
* to correctly process a join
* @param isOptional
*/
public void setOptional(Boolean isOptional) {
if (isOptional == null && Boolean.TRUE.equals(this.isOptional)) {
return;
}
this.isOptional = isOptional;
}
/**
* Returns true if the compare criteria is used as join criteria, but not needed
* during processing.
* @return
*/
public boolean isOptional() {
return isOptional == null || isOptional;
}
public Boolean getIsOptional() {
return isOptional;
}
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
*/
public int hashCode() {
int hc = 0;
hc = HashCodeUtil.hashCode(hc, getOperator());
//allow for semantic equivalence
hc += HashCodeUtil.hashCode(0, getLeftExpression());
hc += HashCodeUtil.hashCode(0, getRightExpression());
return hc;
}
/**
* Override equals() method.
* @param obj Other object
* @return true if objects are equivalent
*/
public boolean equals(Object obj) {
// Use super.equals() to check obvious stuff and variable
if(obj == this) {
return true;
}
if(! (obj instanceof CompareCriteria)) {
return false;
}
//also allow for semantic equivalence on equality
CompareCriteria cc = (CompareCriteria)obj;
return getOperator() == cc.getOperator() &&
(EquivalenceUtil.areEqual(getLeftExpression(), cc.getLeftExpression()) &&
EquivalenceUtil.areEqual(getRightExpression(), cc.getRightExpression())) || (getOperator() == EQ && EquivalenceUtil.areEqual(getLeftExpression(), cc.getRightExpression()) &&
EquivalenceUtil.areEqual(getRightExpression(), cc.getLeftExpression()));
}
/**
* Deep copy of object
* @return Deep copy of object
*/
public Object clone() {
Expression leftCopy = null;
if(getLeftExpression() != null) {
leftCopy = (Expression) getLeftExpression().clone();
}
Expression rightCopy = null;
if(getRightExpression() != null) {
rightCopy = (Expression) getRightExpression().clone();
}
CompareCriteria result = new CompareCriteria(leftCopy, getOperator(), rightCopy);
result.isOptional = isOptional;
return result;
}
} // END CLASS