third_party/checker_framework_dataflow/java/org/checkerframework/dataflow/cfg/node/MarkerNode.java

package org.checkerframework.dataflow.cfg.node;

/*>>>
import org.checkerframework.checker.nullness.qual.Nullable;
*/

import org.checkerframework.dataflow.util.HashCodeUtils;

import java.util.Collection;
import java.util.Collections;

import javax.lang.model.type.TypeKind;
import javax.lang.model.util.Types;

import com.sun.source.tree.Tree;

/**
 * MarkerNodes are no-op Nodes used for debugging information.
 * They can hold a Tree and a message, which will be part of the
 * String representation of the MarkerNode.
 *
 * An example use case for MarkerNodes is representing switch
 * statements.
 *
 * @author Stefan Heule
 * @author Charlie Garrett
 *
 */
public class MarkerNode extends Node {

    protected /*@Nullable*/ Tree tree;
    protected String message;

    public MarkerNode(/*@Nullable*/ Tree tree, String message, Types types) {
        super(types.getNoType(TypeKind.NONE));
        this.tree = tree;
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    @Override
    public Tree getTree() {
        return tree;
    }

    @Override
    public <R, P> R accept(NodeVisitor<R, P> visitor, P p) {
        return visitor.visitMarker(this, p);
    }

    @Override
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("marker ");
        sb.append("(" + message + ")");
        return sb.toString();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null || !(obj instanceof MarkerNode)) {
            return false;
        }
        MarkerNode other = (MarkerNode) obj;
        if (tree == null && other.getTree() != null) {
            return false;
        }

        return getTree().equals(other.getTree())
                && getMessage().equals(other.getMessage());
    }

    @Override
    public int hashCode() {
        int hash = 0;
        if (tree != null) {
            hash = HashCodeUtils.hash(tree);
        }
        return HashCodeUtils.hash(hash, getMessage());
    }

    @Override
    public Collection<Node> getOperands() {
        return Collections.emptyList();
    }
}