openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/Cast.java

/*
 * 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.ArrayList;
import java.util.Collection;
import java.util.Iterator;

import org.apache.openjpa.kernel.Filters;
import org.apache.openjpa.kernel.StoreContext;

/**
 * Represents a cast.
 *
 * @author Abe White
 */
class Cast
    extends Val {

    private final Val _val;
    private final Class _cast;

    /**
     * Constructor. Provide value to cast and type to cast to.
     */
    public Cast(Val val, Class cast) {
        _val = val;
        _cast = cast;
    }

    public Class getType() {
        return _cast;
    }

    public void setImplicitType(Class type) {
    }

    protected Object eval(Object candidate, Object orig,
        StoreContext ctx, Object[] params) {
        return Filters.convert(_val.eval(candidate, orig, ctx, params), _cast);
    }

    protected Collection eval(Collection candidates, Object orig,
        StoreContext ctx, Object[] params) {
        Collection res = _val.eval(candidates, orig, ctx, params);
        if (res == null || res.isEmpty())
            return res;

        Collection casts = new ArrayList(res.size());
        for (Iterator itr = res.iterator(); itr.hasNext();)
            casts.add(Filters.convert(itr.next(), _cast));
        return casts;
    }

    public void acceptVisit(ExpressionVisitor visitor) {
        visitor.enter(this);
        _val.acceptVisit(visitor);
        visitor.exit(this);
    }
}