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/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.qpid.qmf2.common;
// Misc Imports
import java.util.List;
/**
* A class to create and evaluate the BooleanExists Expression
*
* @author Fraser Adams
*/
public final class BooleanExists extends BooleanExpression
{
/**
* Factory method to create an instance of BooleanExists
* @param expr the List of Expressions extracted by parsing the Query predicate
* @return an instance of the concrete BooleanExpression
*/
public Expression create(final List expr) throws QmfException
{
return new BooleanExists(expr);
}
/**
* Basic Constructor primarily used by the prototype instance of each concrete BooleanExpression
*/
public BooleanExists()
{
}
/**
* Main Constructor, uses base class constructor to populate unevaluated operands
* @param expr the List of Expressions extracted by parsing the Query predicate
*/
public BooleanExists(final List expr) throws QmfException
{
super(1, expr);
}
/**
* Evaluate "exists" expression against a QmfData instance.
* N.B. to avoid complexities with types this class treats operands as Strings performing an appropriate evaluation
* of the String that makes sense for a given expression e.g. parsing as a double for {@literal >, >=, <, <= }
*
* @param data the object to evaluate the expression against
* @return true if query matches the QmfData instance, else false.
*/
public boolean evaluate(final QmfData data)
{
return _operands[0] != null;
}
}
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