Implement the negation operator

src/ast/parser.rs

@@ -1,6 +1,7 @@
 use super::astnode;
 use super::astnode::{ASTNode, BinaryExpr};
 use crate::lexer::{token, token::TokenType};
+
 use std::iter;
 use std::result::Result as StdResult;
 
@@ -8,6 +9,7 @@ type Result<T> = StdResult<T, ASTParsingError>;
 
 #[derive(Debug)]
 pub enum ASTParsingError {
+	IncorrectToken(TokenType),
 	UnmatchedBrace,
 }
 
@@ -15,6 +17,7 @@ impl std::fmt::Display for ASTParsingError {
 	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 		match *self {
 			Self::UnmatchedBrace => write!(f, "Unmatched brace"),
+			Self::IncorrectToken(ref token) => write!(f, "Incorrect token {:?}", token),
 		}
 	}
 }
@@ -159,7 +162,7 @@ impl<'a, T: Iterator<Item = token::Token<'a>>> Parser<'a, T> {
 					None => return Err(ASTParsingError::UnmatchedBrace),
 				}
 			}
-			Some(a) => panic!("{:#?}", a),
+			Some(a) => return Err(ASTParsingError::IncorrectToken(a)),
 			None => todo!(),
 		};
 		Ok(node)

src/interpreter/ast_walker.rs

@@ -1,6 +1,6 @@
 use std::fmt::Display;
 
-use super::types;
+use super::types::Value;
 use crate::ast::astnode::{self, UnaryOperator};
 
 #[derive(Debug)]
@@ -14,23 +14,23 @@ impl Display for RuntimeError {
 impl std::error::Error for RuntimeError {}
 
 pub trait Interpret {
-	fn interpret(&self) -> Result<types::Value, RuntimeError>;
+	fn interpret(&self) -> Result<Value, RuntimeError>;
 }
 
 impl Interpret for astnode::ASTNode {
-	fn interpret(&self) -> Result<types::Value, RuntimeError> {
+	fn interpret(&self) -> Result<Value, RuntimeError> {
 		astnode::all_variants!(self, n => n.interpret())
 	}
 }
 
 impl Interpret for astnode::Literal {
-	fn interpret(&self) -> Result<types::Value, RuntimeError> {
+	fn interpret(&self) -> Result<Value, RuntimeError> {
 		Ok(self.clone().into())
 	}
 }
 
 impl Interpret for astnode::BinaryExpr {
-	fn interpret(&self) -> Result<types::Value, RuntimeError> {
+	fn interpret(&self) -> Result<Value, RuntimeError> {
 		let left_val = self.left.interpret().expect("expected lval");
 		let right_val = self.right.interpret().expect("expected rval");
 		match self.operator {
@@ -46,17 +46,21 @@ impl Interpret for astnode::BinaryExpr {
 }
 
 impl Interpret for astnode::UnaryExpr {
-	fn interpret(&self) -> Result<types::Value, RuntimeError> {
+	fn interpret(&self) -> Result<Value, RuntimeError> {
 		let val = self.right.interpret()?;
 		match self.operator {
-			UnaryOperator::Bang => Ok(types::Value::Bool(!val.truthy())),
-			UnaryOperator::Minus => todo!(),
+			UnaryOperator::Bang => Ok(Value::Bool(!val.truthy())),
+			UnaryOperator::Minus => match val {
+				Value::Int(i) => Ok(Value::Int(-i)),
+				Value::Float(f) => Ok(Value::Float(-f)),
+				_ => Err(RuntimeError),
+			},
 		}
 	}
 }
 
 impl Interpret for astnode::GroupingExpr {
-	fn interpret(&self) -> Result<types::Value, RuntimeError> {
+	fn interpret(&self) -> Result<Value, RuntimeError> {
 		self.0.interpret()
 	}
 }