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AspClassic.Parser/Expression.cs

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+#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)
+	{
+	}
+}