From b9b8c8e24b19b5fe4ea1e646349f290a242f1753 Mon Sep 17 00:00:00 2001
From: Brandon Dyck <brandon@dyck.us>
Date: Mon, 26 Jun 2023 13:47:31 -0700
Subject: [PATCH] Added an AST printer

---
 ASTPrinter.cs | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 ASTPrinter.cs

diff --git a/ASTPrinter.cs b/ASTPrinter.cs
new file mode 100644
index 0000000..a5ae86c
--- /dev/null
+++ b/ASTPrinter.cs
@@ -0,0 +1,46 @@
+using System;
+using System.IO;
+using Finn.AST;
+
+namespace Finn;
+
+class ASTPrinter : IVisitor<string>
+{
+	string print(Expr expr)
+	{
+		return expr.accept(this);
+	}
+
+	private string parenthesize(string name, params Expr[] exprs)
+	{
+		var w = new StringWriter();
+		w.Write($"({name}");
+		foreach (Expr expr in exprs)
+		{
+			w.Write(" ");
+			w.Write(expr.accept(this));
+		}
+		w.Write(")");
+		return w.ToString();
+	}
+
+	public string visitBinaryExpr(Binary expr)
+	{
+		return parenthesize(expr.Op.lexeme, expr.Left, expr.Right);
+	}
+
+	public string visitGroupingExpr(Grouping expr)
+	{
+		return parenthesize("group", expr.Expression);
+	}
+
+	public string visitLiteralExpr(Literal expr)
+	{
+		return expr.Value.ToString() ?? "";
+	}
+
+	public string visitUnaryExpr(Unary expr)
+	{
+		return parenthesize(expr.Op.lexeme, expr.Right);
+	}
+}