org.apache.openjpa.jdbc.kernel.exps.ConstInstanceofExpression 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
* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.openjpa.jdbc.kernel.exps;
import java.util.Map;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;
import org.apache.openjpa.kernel.Filters;
import org.apache.openjpa.kernel.exps.ExpressionVisitor;
/**
* Tests whether a value is an instance of a class.
*
* @author Abe White
*/
class ConstInstanceofExpression
implements Exp {
private final Const _const;
private final Class _cls;
/**
* Constructor. Supply the constant to test and the class.
*/
public ConstInstanceofExpression(Const val, Class cls) {
_const = val;
_cls = Filters.wrap(cls);
}
public ExpState initialize(Select sel, ExpContext ctx, Map contains) {
return _const.initialize(sel, ctx, 0);
}
public void appendTo(Select sel, ExpContext ctx, ExpState state,
SQLBuffer buf) {
_const.calculateValue(sel, ctx, state, null, null);
if (_cls.isInstance(_const.getValue(ctx, state)))
buf.append("1 = 1");
else
buf.append("1 <> 1");
}
public void selectColumns(Select sel, ExpContext ctx, ExpState state,
boolean pks) {
_const.selectColumns(sel, ctx, state, pks);
}
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
_const.acceptVisit(visitor);
visitor.exit(this);
}
}