finn-lang/ASTPrinter.cs

using System;
using System.IO;
using Finn.AST;

namespace Finn;

class ASTPrinter : IVisitor<string>
{
	public 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);
	}
}