From be36d4697d5477a926f61d5d65b0daa186d81609 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Fri, 22 Jan 2016 02:55:07 -0800
Subject: [PATCH] Pretty-print evaluated AST nodes

---
 src/eval.rs   |  2 +-
 src/parser.rs | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/eval.rs b/src/eval.rs
index 53a79a5..7bd90c1 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -73,7 +73,7 @@ impl Evaluator {
             }
         }
 
-        format!("{:?}", node) //TODO make better
+        format!("{}", node) //TODO make better
     }
 
     fn step(&mut self, node: ASTNode) -> ASTNode {
diff --git a/src/parser.rs b/src/parser.rs
index e9e9f6f..e9b8cbe 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,3 +1,4 @@
+use std::fmt;
 use tokenizer::{Token, Kw, Op};
 
 /* Grammar
@@ -45,6 +46,28 @@ pub enum Expression {
     Call(String, Vec<Expression>),
 }
 
+impl fmt::Display for ASTNode {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::ASTNode::*;
+        match self {
+            &ExprNode(ref expr) => write!(f, "{}", expr),
+            &FuncNode(_) => write!(f, "UNIMPLEMENTED"),
+        }
+    }
+}
+
+impl fmt::Display for Expression {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::Expression::*;
+        match self {
+            &Null => write!(f, "null"),
+            &StringLiteral(ref s) => write!(f, "\"{}\"", s),
+            &Number(n) => write!(f, "{}", n),
+            _ => write!(f, "UNIMPLEMENTED"),
+        }
+    }
+}
+
 pub type AST = Vec<ASTNode>;
 
 type Precedence = u8;