chore: initial git load of code space

src/Strata.SqlTools.Rules/Rule/Expression/Expression.cs

@@ -0,0 +1,17 @@
+namespace Strata.SqlTools.Rules.Rule.Expression;
+
+/// <summary>
+/// Base class for all rule expressions.
+/// </summary>
+#pragma warning disable CS0660, CS0661
+public abstract partial class Expression : IVisitable
+#pragma warning restore CS0660, CS0661
+{
+    /// <summary>
+    /// Accepts a visitor and allows it to process this rule expression.
+    /// </summary>
+    /// <typeparam name="T">The return type of the visitor.</typeparam>
+    /// <param name="visitor">The visitor to accept.</param>
+    /// <returns>The result of the visitor's processing.</returns>
+    public abstract T Accept<T>(IVisitor<T> visitor);
+}