Add project files.

Parser/ASTNode.cs

@@ -0,0 +1,78 @@
+using System.Collections;
+using System.Reflection;
+using System.Text;
+
+namespace Parser;
+
+public record ASTNode
+{
+    public string Accept(IAccepter compiler)
+    {
+        return ((string)compiler.GetType()
+            .GetMethod("Visit", BindingFlags.Public | BindingFlags.Instance, new[] { this.GetType() })!
+            .Invoke(compiler, new[] { this })!)!;
+    }
+
+    public static string PrintNode(ASTNode node)
+    {
+        // print type name and string representation of all its fields
+        var type = node.GetType();
+        var fields = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
+        var sb = new StringBuilder();
+        sb.Append(type.Name);
+        sb.Append("(");
+        int i = 0;
+        foreach (var field in fields)
+        {
+            if (i++ > 0) sb.Append(",");
+            var value = field.GetValue(node);
+            if (value is ASTNode valueNode)
+            {
+                sb.Append(PrintNode(valueNode));
+            }
+            else
+            {
+                sb.Append(value);
+            }
+
+            // if field is list - print all its elements
+            if (field.PropertyType.IsGenericType && field.PropertyType.GetGenericTypeDefinition() == typeof(List<>))
+            {
+                var list = (IList)field.GetValue(node);
+                sb.Append("[");
+                int j = 0;
+                sb.AppendLine();
+                foreach (var item in list)
+                {
+                    if (j++ > 0)
+                    {
+                        sb.Append(",");
+                        sb.AppendLine();
+                    }
+
+                    if (item is ASTNode itemNode)
+                    {
+                        sb.Append(PrintNode(itemNode));
+
+                    }
+                    else
+                    {
+                        sb.Append(item);
+                    }
+
+                }
+
+                sb.Append("]");
+            }
+        }
+
+        sb.Append(")");
+        return sb.ToString();
+
+
+    }
+}
+
+public interface IAccepter
+{
+}