/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.metapath.cst;
   
   import java.util.List;
   import java.util.Objects;
  
  import dev.metaschema.core.metapath.IExpression;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * An immutable expression with a single sub-expression.
   */
  public abstract class AbstractUnaryExpression
      extends AbstractExpression {
    @NonNull
    private final IExpression expr;
  
    /**
     * Construct a new unary expression.
     *
     * @param text
     *          the parsed text of the expression
     * @param expr
     *          the single sub-expression
     */
    public AbstractUnaryExpression(@NonNull String text, @NonNull IExpression expr) {
      super(text);
      this.expr = Objects.requireNonNull(expr, "expr");
    }
  
    /**
     * Retrieve the single child sub-expression.
     *
     * @return the sub-expression
     */
    @NonNull
    public IExpression getChild() {
      return expr;
    }
  
    @SuppressWarnings("null")
    @Override
    public List<? extends IExpression> getChildren() {
      return List.of(expr);
    }
  }