From ec5b3371fc7dac24f6a55fb5d614a0c97aca3232 Mon Sep 17 00:00:00 2001
From: Kasper <kasperkh.kh@gmail.com>
Date: Wed, 25 Dec 2019 23:56:43 +0100
Subject: [PATCH] Evaluation of negative numbers

---
 src/evaluator.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/evaluator.rs b/src/evaluator.rs
index 544b545..b33ce96 100644
--- a/src/evaluator.rs
+++ b/src/evaluator.rs
@@ -117,6 +117,11 @@ fn evaluate_node(ast_node: &AstNode) -> Result<Answer, String> {
       let child_answer = evaluate_node(child_node)?;
       Ok(Answer::new(child_answer.value, unit.clone()))
     },
+    Token::Negative => {
+      let child_node = children.get(0).expect("Negative has no child[0]");
+      let child_answer = evaluate_node(child_node)?;
+      Ok(Answer::new(-child_answer.value, child_answer.unit))
+    },
     Token::Paren => {
       let child_node = children.get(0).expect("Paren has no child[0]");
       return evaluate_node(child_node)
@@ -248,8 +253,5 @@ fn evaluate_node(ast_node: &AstNode) -> Result<Answer, String> {
         }
       }
     },
-    _ => {
-      Err(format!("Unexpected ast node {:?}", token))
-    },
   }
 }