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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.openjpa.kernel.exps;
import java.util.Collection;
import org.apache.openjpa.kernel.Filters;
import org.apache.openjpa.kernel.StoreContext;
/**
* Expression that compares two others.
*
* @author Abe White
*/
abstract class CompareExpression
extends Exp {
private final Val _val1;
private final Val _val2;
/**
* Constructor. Supply values to compare.
*/
public CompareExpression(Val val1, Val val2) {
_val1 = val1;
_val2 = val2;
}
protected boolean eval(Object candidate, Object orig,
StoreContext ctx, Object[] params) {
Object o1 = _val1.eval(candidate, orig, ctx, params);
Object o2 = _val2.eval(candidate, orig, ctx, params);
if (o1 != null && o2 != null) {
Class c = Filters.promote(o1.getClass(), o2.getClass());
o1 = Filters.convert(o1, c);
o2 = Filters.convert(o2, c);
}
return compare(o1, o2);
}
protected boolean eval(Collection candidates, StoreContext ctx,
Object[] params) {
Collection c1 = _val1.eval(candidates, null, ctx, params);
Collection c2 = _val2.eval(candidates, null, ctx, params);
Object o1 = (c1 == null || c1.isEmpty()) ? null
: c1.iterator().next();
Object o2 = (c2 == null || c2.isEmpty()) ? null
: c2.iterator().next();
if (o1 != null && o2 != null) {
Class c = Filters.promote(o1.getClass(), o2.getClass());
o1 = Filters.convert(o1, c);
o2 = Filters.convert(o2, c);
}
return compare(o1, o2);
}
/**
* Compare the two values.
*/
protected abstract boolean compare(Object o1, Object o2);
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
_val1.acceptVisit(visitor);
_val2.acceptVisit(visitor);
visitor.exit(this);
}
}