org.apache.openjpa.kernel.exps.InstanceofExpression Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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
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* KIND, either express or implied. See the License for the
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*/
package org.apache.openjpa.kernel.exps;
import java.util.Collection;
import org.apache.openjpa.kernel.Filters;
import org.apache.openjpa.kernel.StoreContext;
/**
* Tests whether a value is an instance of a class.
*
* @author Abe White
*/
class InstanceofExpression
extends Exp {
private final Val _val;
private final Class _cls;
/**
* Constructor; supply value and class.
*/
public InstanceofExpression(Val val, Class cls) {
_val = val;
_cls = Filters.wrap(cls);
}
/**
* Evaluate the expression for the given context candidate and original
* candidate.
*/
protected boolean eval(Object candidate, Object orig,
StoreContext ctx, Object[] params) {
return _cls.isInstance(_val.eval(candidate, orig, ctx, params));
}
/**
* Evaluate the expression for the given group.
*/
protected boolean eval(Collection candidates, StoreContext ctx,
Object[] params) {
Collection c = _val.eval(candidates, null, ctx, params);
Object o = (c == null || c.isEmpty()) ? null : c.iterator().next();
return _cls.isInstance(o);
}
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
_val.acceptVisit(visitor);
visitor.exit(this);
}
}