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/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.optimize.evaluation;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import proguard.classfile.*;
import proguard.classfile.visitor.*;
import proguard.evaluation.value.*;
import proguard.optimize.OptimizationInfoMemberFilter;
import proguard.optimize.info.*;

/**
 * This ClassVisitor propagates the value of the $VALUES field to the values()
 * method in the simple enum classes that it visits.
 *
 * @see SimpleEnumMarker
 * @author Eric Lafortune
 */
public class SimpleEnumArrayPropagator
implements   ClassVisitor,
             MemberVisitor
{
    private static final Logger logger = LogManager.getLogger(SimpleEnumArrayPropagator.class);


    private final MemberVisitor fieldArrayFinder      = new MemberDescriptorFilter("[I", this);
    private final MemberVisitor methodArrayPropagator = new OptimizationInfoMemberFilter(
                                                        new MemberDescriptorFilter("()[I", this));
    private final ValueFactory  valueFactory          = new ParticularValueFactory();

    private Value array;


    // Implementations for ClassVisitor.

    @Override
    public void visitAnyClass(Clazz clazz) { }


    @Override
    public void visitProgramClass(ProgramClass programClass)
    {
        // Find the array of the "int[] $VALUES" field.
        array = null;

        programClass.fieldsAccept(fieldArrayFinder);

        if (array != null)
        {
            // Update the return value of the "int[] values()" method.
            programClass.methodsAccept(methodArrayPropagator);
        }
    }


    // Implementations for MemberVisitor.

    public void visitProgramField(ProgramClass programClass, ProgramField programField)
    {
        array = StoringInvocationUnit.getFieldValue(programField);
    }


    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
    {
        // Set the array value with the found array length. We can't use
        // the original array, because its elements might get overwritten.
        Value propagatedArray =
            valueFactory.createArrayReferenceValue("I",
                                                   null,
                                                   array.referenceValue().arrayLength(valueFactory));

        logger.debug("SimpleEnumArrayPropagator: [{}.{}{}]: propagating [{}] as return value",
                     programClass.getName(),
                     programMethod.getName(programClass),
                     programMethod.getDescriptor(programClass),
                     propagatedArray
        );

        setMethodReturnValue(programMethod, propagatedArray);
    }


    // Small utility methods.

    private static void setMethodReturnValue(Method method, Value value)
    {
        ProgramMethodOptimizationInfo.getProgramMethodOptimizationInfo(method).setReturnValue( value);
    }
}