#define DEBUG
using System.Diagnostics;

namespace AspClassic.Parser;

/// <summary>
/// A parse tree for an expression.
/// </summary>
public class Expression : Tree
{
	/// <summary>
	/// Whether the expression is constant or not.
	/// </summary>
	public virtual bool IsConstant => false;

	public override bool IsBad => base.Type == TreeType.SyntaxError;

	/// <summary>
	/// Creates a bad expression.
	/// </summary>
	/// <param name="span">The location of the parse tree.</param>
	/// <returns>A bad expression.</returns>
	public static Expression GetBadExpression(Span span)
	{
		return new Expression(span);
	}

	protected Expression(TreeType type, Span span)
		: base(type, span)
	{
		Debug.Assert(type >= TreeType.SimpleNameExpression && type <= TreeType.GetTypeExpression);
	}

	private Expression(Span span)
		: base(TreeType.SyntaxError, span)
	{
	}
}