InvokespecialHandler.java

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package org.eolang.opeo.decompilation.handlers;

import java.util.Collections;
import java.util.List;
import org.eolang.opeo.ast.AstNode;
import org.eolang.opeo.ast.Labeled;
import org.eolang.opeo.ast.Super;
import org.eolang.opeo.ast.This;
import org.eolang.opeo.decompilation.DecompilerState;
import org.eolang.opeo.decompilation.InstructionHandler;
import org.objectweb.asm.Type;

/**
 * Invokespecial instruction handler.
 *
 * @since 0.1
 * @todo #229:90min Is Labeled Class an Abstraction Failure?
 *  As you can see in {@link InvokespecialHandler} we use many 'instanceof' checks.
 *  This is a clear sign that the class hierarchy is not well designed.
 *  The original problem lies in the {@link Labeled} class.
 *  We need to find more elegant solutions to handle labels in AST.
 * @checkstyle NoJavadocForOverriddenMethodsCheck (500 lines)
 * @checkstyle MultilineJavadocTagsCheck (500 lines)
 */
public final class InvokespecialHandler implements InstructionHandler {

    /**
     * Handle invokespecial instruction.
     * @param state Current instruction to handle together with operand stack and variables.
     * @todo #344:90min Super and Constructor classes ambiguity.
     *  Recently I removed the following code from this method:
     *  {@code
     *    state.stack().push(
     *      new Constructor(
     *        target,
     *        new Attributes().descriptor(descriptor).interfaced(interfaced),
     *        args
     *      )
     *    );
     *  }
     *  The reason behind this integration test with
     *  WebProperties$Resources$Chain$Strategy$Content.xmir class.
     *  See {@link JeoAndOpeoTest} for more info.
     *  We need to use both Super and This classes.
     *  Moreover, we might need to add some other representations.
     *  Don't forget to remove suppressions.
     */
    @Override
    @SuppressWarnings("PMD.UnusedLocalVariable")
    public void handle(final DecompilerState state) {
        final String type = (String) state.operand(0);
        final String name = (String) state.operand(1);
        final String descriptor = (String) state.operand(2);
        final boolean interfaced = (boolean) state.operand(3);
        final List<AstNode> args = state.stack().pop(
            Type.getArgumentCount(descriptor)
        );
        Collections.reverse(args);
        final AstNode target = state.stack().pop();
        if (InvokespecialHandler.isThis(target)) {
            state.stack().push(
                new Super(target, args, descriptor, type, name)
            );
        } else {
            state.stack().push(
                new Super(target, args, descriptor, type, name)
            );
        }
    }

    /**
     * Check if the node is "this".
     * @param candidate Node to check
     * @return True if the node is "this"
     */
    private static boolean isThis(final AstNode candidate) {
        final boolean result;
        if (candidate instanceof This) {
            result = true;
        } else if (candidate instanceof Labeled) {
            result = InvokespecialHandler.isThis(((Labeled) candidate).origin());
        } else {
            result = false;
        }
        return result;
    }

}