dataflow/src/main/java/org/checkerframework/dataflow/expression/Unknown.java

package org.checkerframework.dataflow.expression;

import com.sun.source.tree.Tree;
import javax.lang.model.type.TypeMirror;
import org.checkerframework.checker.interning.qual.UsesObjectEquals;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.dataflow.analysis.Store;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.javacutil.AnnotationProvider;
import org.checkerframework.javacutil.TreeUtils;

/** Stands for any expression that the Dataflow Framework lacks explicit support for. */
@UsesObjectEquals
public class Unknown extends JavaExpression {

  /** String representation of the expression that has no corresponding {@code JavaExpression}. */
  private final String originalExpression;
  /**
   * Create a new Unknown JavaExpression.
   *
   * @param type the Java type of this
   */
  public Unknown(TypeMirror type) {
    this(type, "?");
  }

  /**
   * Create a new Unknown JavaExpression.
   *
   * @param type the Java type of this
   * @param originalExpression String representation of the expression that has no corresponding
   *     {@code JavaExpression}
   */
  public Unknown(TypeMirror type, String originalExpression) {
    super(type);
    this.originalExpression = originalExpression;
  }

  /**
   * Create a new Unknown JavaExpression.
   *
   * @param tree a tree that does not have a corresponding {@code JavaExpression}
   */
  public Unknown(Tree tree) {
    this(TreeUtils.typeOf(tree), TreeUtils.toStringTruncated(tree, 40));
  }

  /**
   * Create a new Unknown JavaExpression.
   *
   * @param node a node that does not have a corresponding {@code JavaExpression}
   */
  public Unknown(Node node) {
    this(node.getType(), node.toString());
  }

  @Override
  public boolean equals(@Nullable Object obj) {
    return obj == this;
  }

  // Overridden to avoid an error "overrides equals, but does not override hashCode"
  @Override
  public int hashCode() {
    return System.identityHashCode(this);
  }

  @Override
  public String toString() {
    return originalExpression;
  }

  @Override
  public boolean containsOfClass(Class<? extends JavaExpression> clazz) {
    return getClass() == clazz;
  }

  @Override
  public boolean isDeterministic(AnnotationProvider provider) {
    return false;
  }

  @Override
  public boolean isUnassignableByOtherCode() {
    return false;
  }

  @Override
  public boolean isUnmodifiableByOtherCode() {
    return false;
  }

  @Override
  public boolean syntacticEquals(JavaExpression je) {
    return this == je;
  }

  @Override
  public boolean containsSyntacticEqualJavaExpression(JavaExpression other) {
    return this.syntacticEquals(other);
  }

  @Override
  public boolean containsModifiableAliasOf(Store<?> store, JavaExpression other) {
    return true;
  }

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