org.apache.openjpa.kernel.exps.BoundVariable Maven / Gradle / Ivy
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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 org.apache.openjpa.kernel.StoreContext;
/**
* Represents a bound variable. Variables are aliased to the
* collection that is stated to contain them in the query.
* When the query is evaluated, expressions containing variables will be
* executed once for every element in the collection.
*
* @author Abe White
*/
class BoundVariable
extends Val {
private Class _type = null;
private Object _val = null;
/**
* Constructor. Provide variable name and type.
*/
public BoundVariable(Class type) {
_type = type;
}
/**
* Set the value this variable should take for the current iteration.
*
* @return false if the type is incompatible with the variable's
* declared type
*/
public boolean setValue(Object value) {
if (value != null && !_type.isAssignableFrom(value.getClass()))
return false;
_val = value;
return true;
}
public boolean isVariable() {
return true;
}
public Class getType() {
return _type;
}
public void setImplicitType(Class type) {
_type = type;
}
/**
* Cast this value to the given type.
*/
public void castTo(Class type) {
// incompatible types?
if (!_type.isAssignableFrom(type)
&& !type.isAssignableFrom(_type))
throw new ClassCastException(_type.getName());
_type = type;
}
protected Object eval(Object candidate, Object orig,
StoreContext ctx, Object[] params) {
return _val;
}
}