dataflow/src/main/java/org/checkerframework/dataflow/cfg/builder/ExtendedNode.java

package org.checkerframework.dataflow.cfg.builder;

import org.checkerframework.dataflow.cfg.block.BlockImpl;
import org.checkerframework.dataflow.cfg.builder.ExtendedNode.ExtendedNodeType;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.javacutil.BugInCF;

/**
 * An extended node can be one of several things (depending on its {@code type}):
 *
 * <ul>
 *   <li><em>NODE</em>: {@link CFGBuilder.NodeHolder}. An extended node of this type is just a
 *       wrapper for a {@link Node} (that cannot throw exceptions).
 *   <li><em>EXCEPTION_NODE</em>: {@link CFGBuilder.NodeWithExceptionsHolder}. A wrapper for a
 *       {@link Node} which can throw exceptions. It contains a label for every possible exception
 *       type the node might throw.
 *   <li><em>UNCONDITIONAL_JUMP</em>: {@link CFGBuilder.UnconditionalJump}. An unconditional jump to
 *       a label.
 *   <li><em>TWO_TARGET_CONDITIONAL_JUMP</em>: {@link CFGBuilder.ConditionalJump}. A conditional
 *       jump with two targets for both the 'then' and 'else' branch.
 * </ul>
 */
@SuppressWarnings("nullness") // TODO
abstract class ExtendedNode {

  /** The basic block this extended node belongs to (as determined in phase two). */
  protected BlockImpl block;

  /** Type of this node. */
  protected final ExtendedNodeType type;

  /** Does this node terminate the execution? (e.g., "System.exit()") */
  protected boolean terminatesExecution = false;

  /**
   * Create a new ExtendedNode.
   *
   * @param type the type of this node
   */
  protected ExtendedNode(ExtendedNodeType type) {
    this.type = type;
  }

  /** Extended node types (description see above). */
  public enum ExtendedNodeType {
    NODE,
    EXCEPTION_NODE,
    UNCONDITIONAL_JUMP,
    CONDITIONAL_JUMP
  }

  public ExtendedNodeType getType() {
    return type;
  }

  public boolean getTerminatesExecution() {
    return terminatesExecution;
  }

  public void setTerminatesExecution(boolean terminatesExecution) {
    this.terminatesExecution = terminatesExecution;
  }

  /**
   * Returns the node contained in this extended node (only applicable if the type is {@code NODE}
   * or {@code EXCEPTION_NODE}).
   *
   * @return the node contained in this extended node (only applicable if the type is {@code NODE}
   *     or {@code EXCEPTION_NODE})
   */
  public Node getNode() {
    throw new Error("Do not call");
  }

  /**
   * Returns the label associated with this extended node (only applicable if type is {@link
   * ExtendedNodeType#CONDITIONAL_JUMP} or {@link ExtendedNodeType#UNCONDITIONAL_JUMP}).
   *
   * @return the label associated with this extended node (only applicable if type is {@link
   *     ExtendedNodeType#CONDITIONAL_JUMP} or {@link ExtendedNodeType#UNCONDITIONAL_JUMP})
   */
  public Label getLabel() {
    throw new Error("Do not call");
  }

  public BlockImpl getBlock() {
    return block;
  }

  public void setBlock(BlockImpl b) {
    this.block = b;
  }

  @Override
  public String toString() {
    throw new BugInCF("DO NOT CALL ExtendedNode.toString(). Write your own.");
  }

  /**
   * Returns a verbose string representation of this, useful for debugging.
   *
   * @return a string representation of this
   */
  public abstract String toStringDebug();
}