com.mysema.query.support.EnumConversion Maven / Gradle / Ivy
/*
* Copyright 2012, Mysema Ltd
*
* Licensed 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 com.mysema.query.support;
import java.util.Collections;
import java.util.List;
import com.google.common.base.Preconditions;
import com.mysema.query.types.Expression;
import com.mysema.query.types.FactoryExpressionBase;
import com.mysema.query.types.Visitor;
/**
* EnumConversion ensures that the results of an enum projection confirm to the type of the
* projection expression
*
* @author tiwe
*
* @param
*/
public class EnumConversion extends FactoryExpressionBase {
private static final long serialVersionUID = 7840412008633901748L;
private final List> exprs;
private final T[] values;
public EnumConversion(Expression expr) {
super(expr.getType());
Class type = getType();
Preconditions.checkArgument(type.isEnum(), "%s is not an enum", type);
exprs = Collections.>singletonList(expr);
values = type.getEnumConstants();
}
@Override
public R accept(Visitor v, C context) {
return v.visit(this, context);
}
@Override
public List> getArgs() {
return exprs;
}
@Override
public T newInstance(Object... args) {
if (args[0] != null) {
if (args[0] instanceof String) {
@SuppressWarnings("unchecked") //The expression type is an enum
T rv = (T) Enum.valueOf(getType().asSubclass(Enum.class), (String)args[0]);
return rv;
} else if (args[0] instanceof Number) {
return values[((Number)args[0]).intValue()];
} else {
@SuppressWarnings("unchecked")
T rv = (T)args[0];
return rv;
}
} else {
return null;
}
}
}