/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * 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 proguard.classfile.attribute.visitor;

import proguard.classfile.Clazz;
import proguard.classfile.Method;
import proguard.classfile.attribute.Attribute;
import proguard.classfile.attribute.CodeAttribute;

/**
 * This {@link AttributeVisitor} delegates its visits to another given
 * {@link AttributeVisitor}, but only when the visited attribute has the proper
 * processing flags.
 *
 * @author Johan Leys
 */
public class AttributeProcessingFlagFilter
implements   AttributeVisitor
{
    private final int              requiredSetProcessingFlags;
    private final int              requiredUnsetProcessingFlags;
    private final AttributeVisitor attributeVisitor;


    /**
     * Creates a new AttributeProcessingFlagFilter.
     *
     * @param requiredSetProcessingFlags   the attribute processing flags that should be set.
     * @param requiredUnsetProcessingFlags the attribute processing flags that should beunset.
     * @param attributeVisitor             the <code>AttributeVisitor</code> to which visits will be delegated.
     */
    public AttributeProcessingFlagFilter(int              requiredSetProcessingFlags,
                                         int              requiredUnsetProcessingFlags,
                                         AttributeVisitor attributeVisitor)
    {
        this.requiredSetProcessingFlags   = requiredSetProcessingFlags;
        this.requiredUnsetProcessingFlags = requiredUnsetProcessingFlags;
        this.attributeVisitor             = attributeVisitor;
    }


    // Implementations for AttributeVisitor.

    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}


    public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
    {
        if (accepted(codeAttribute.processingFlags))
        {
            codeAttribute.accept(clazz, method, attributeVisitor);
        }
    }

    // Small utility methods.

    private boolean accepted(int processingFlags)
    {
        return (requiredSetProcessingFlags & ~processingFlags) == 0 &&
               (requiredUnsetProcessingFlags &  processingFlags) == 0;
    }
}
