org.apache.openjpa.jdbc.kernel.exps.BindVariableExpression 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.exps.ExpressionVisitor;
/**
* Binds a variable to a value. Typically, the {@link #initialize} and
* {@link #getJoins} methods of this expression are not called. They are
* only called if the variable being bound is otherwise unused in the filter,
* in which case we must at least make the joins to the variable because the
* act of binding a variable should at least guarantee that an instance
* represting the variable could exist (i.e. the binding collection is not
* empty).
*
* @author Abe White
*/
class BindVariableExpression
extends EmptyExpression {
private final Variable _var;
/**
* Constructor. Supply values.
*/
public BindVariableExpression(Variable var, PCPath val, boolean key) {
if (key)
val.getKey();
var.setPCPath(val);
_var = var;
}
public Variable getVariable() {
return _var;
}
public ExpState initialize(Select sel, ExpContext ctx, Map contains) {
return _var.initialize(sel, ctx, 0);
}
public void appendTo(Select sel, ExpContext ctx, ExpState state,
SQLBuffer buf) {
buf.append("1 = 1");
}
public void selectColumns(Select sel, ExpContext ctx, ExpState state,
boolean pks) {
}
public void acceptVisit(ExpressionVisitor visitor) {
visitor.enter(this);
_var.acceptVisit(visitor);
visitor.exit(this);
}
}