dataflow/src/main/java/org/checkerframework/dataflow/util/NodeUtils.java

package org.checkerframework.dataflow.util;

import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.tree.JCTree;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.type.TypeKind;
import org.checkerframework.dataflow.cfg.node.BooleanLiteralNode;
import org.checkerframework.dataflow.cfg.node.ConditionalNotNode;
import org.checkerframework.dataflow.cfg.node.ConditionalOrNode;
import org.checkerframework.dataflow.cfg.node.FieldAccessNode;
import org.checkerframework.dataflow.cfg.node.MethodInvocationNode;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.javacutil.ElementUtils;
import org.checkerframework.javacutil.TypesUtils;

/** A utility class to operate on a given {@link Node}. */
public class NodeUtils {

  /**
   * Returns true iff {@code node} corresponds to a boolean typed expression (either the primitive
   * type {@code boolean}, or class type {@link java.lang.Boolean}).
   *
   * @return true iff {@code node} corresponds to a boolean typed expression (either the primitive
   *     type {@code boolean}, or class type {@link java.lang.Boolean})
   */
  public static boolean isBooleanTypeNode(Node node) {

    if (node instanceof ConditionalOrNode) {
      return true;
    }

    // not all nodes have an associated tree, but those are all not of a boolean type.
    Tree tree = node.getTree();
    if (tree == null) {
      return false;
    }

    Type type = ((JCTree) tree).type;
    if (TypesUtils.isBooleanType(type)) {
      return true;
    }

    return false;
  }

  /**
   * Returns true iff {@code node} is a {@link FieldAccessNode} that is an access to an array's
   * length.
   *
   * @return true iff {@code node} is a {@link FieldAccessNode} that is an access to an array's
   *     length
   */
  public static boolean isArrayLengthFieldAccess(Node node) {
    if (!(node instanceof FieldAccessNode)) {
      return false;
    }
    FieldAccessNode fieldAccess = (FieldAccessNode) node;
    return fieldAccess.getFieldName().equals("length")
        && fieldAccess.getReceiver().getType().getKind() == TypeKind.ARRAY;
  }

  /** Returns true iff {@code node} is an invocation of the given method. */
  public static boolean isMethodInvocation(
      Node node, ExecutableElement method, ProcessingEnvironment env) {
    if (!(node instanceof MethodInvocationNode)) {
      return false;
    }
    ExecutableElement invoked = ((MethodInvocationNode) node).getTarget().getMethod();
    return ElementUtils.isMethod(invoked, method, env);
  }

  /**
   * Returns true if the given node statically evaluates to {@code value} and has no side effects.
   *
   * @param n a node
   * @param value the boolean value that the node is tested against
   * @return true if the node is equivalent to a literal with value {@code value}
   */
  public static boolean isConstantBoolean(Node n, boolean value) {
    if (n instanceof BooleanLiteralNode) {
      return ((BooleanLiteralNode) n).getValue() == value;
    } else if (n instanceof ConditionalNotNode) {
      return isConstantBoolean(((ConditionalNotNode) n).getOperand(), !value);
    } else {
      return false;
    }
  }
}