openjpa-kernel/src/main/java/org/apache/openjpa/kernel/exps/NotExpression.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.Collection;

import org.apache.openjpa.kernel.StoreContext;

/**
 * An expression that NOT's another.
 *
 * @author Abe White
 */
class NotExpression
    extends Exp {

    private final Exp _exp;

    /**
     * Constructor. Supply expression to negate.
     */
    public NotExpression(Exp exp) {
        _exp = exp;
    }

    protected boolean eval(Object candidate, Object orig,
        StoreContext ctx, Object[] params) {
        return !_exp.evaluate(candidate, orig, ctx, params);
    }

    protected boolean eval(Collection candidates, StoreContext ctx,
        Object[] params) {
        return !_exp.evaluate(candidates, ctx, params);
    }

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