Fixed unary minus

Cargo.lock

@@ -3,5 +3,5 @@
 version = 4
 
 [[package]]
-name = "tea"
+name = "matcha"
 version = "0.1.0"

src/interpret.rs

@@ -35,7 +35,7 @@ fn get_value(v: Value, scopes: &mut [Scope]) -> Result<TeaValue, InterpreterErro
 	match v {
 		Value::Lit(t) => Ok(t),
 		Value::Id(s) => {
-			match scopes.iter().rev().skip_while(|scope| !scope.contains_key(&s)).next() {
+			match scopes.iter().rev().find(|scope| scope.contains_key(&s)) {
 				None => Err(InterpreterError::new("undefined variable")),
 				Some(scope) => match scope.get(&s).unwrap() {
 					VarType::Const(t) => Ok(t.clone()),

src/lex.rs

@@ -67,6 +67,7 @@ pub fn lex_tokens(s: &str) -> Result<Vec<Token>, (Vec<Token>, &str)> {
 	let mut tokens: Vec<Token> = vec![];
 	loop {
 		if input.is_empty() {
+			println!("tokens: {tokens:?}\n\n");
 			return Ok(tokens);
 		}
 		try_parse!(parse_literal(input), tokens, input);

src/lex/symbol.rs

@@ -6,6 +6,8 @@ pub enum Symbol {
 	Semicolon,
 	OpenBrace,
 	CloseBrace,
+	OpenParen,
+	CloseParen,
 }
 
 pub fn parse_symbol(input: &str) -> Option<(Token, &str)> {
@@ -16,6 +18,8 @@ pub fn parse_symbol(input: &str) -> Option<(Token, &str)> {
 		';' => Some((Token::Sym(Symbol::Semicolon), input)),
 		'{' => Some((Token::Sym(Symbol::OpenBrace), input)),
 		'}' => Some((Token::Sym(Symbol::CloseBrace), input)),
+		'(' => Some((Token::Sym(Symbol::OpenParen), input)),
+		')' => Some((Token::Sym(Symbol::CloseParen), input)),
 		_ => None
 	}
 }

src/parse.rs

@@ -71,13 +71,29 @@ fn next_expr_end(tokens: &[Token]) -> usize {
 
 fn next_block_end(tokens: &[Token]) -> Result<usize, ParseError> {
 	let mut index = 0;
+	let mut block_count = 0usize;
 	loop {
-		let token = tokens.get(index);
-		if token.is_none() {
-			return Err(ParseError::new("} expected"));
+		match tokens.get(index) {
+			Some(Token::Sym(Symbol::OpenBrace)) => block_count += 1,
+			Some(Token::Sym(Symbol::CloseBrace)) if block_count == 0 => return Ok(index),
+			Some(Token::Sym(Symbol::CloseBrace)) => block_count -= 1,
+			None => return Err(ParseError::new("mismatched {")),
+			_ => (),
 		}
-		if matches!(token, Some(Token::Sym(Symbol::CloseBrace))) {
-			return Ok(index);
+		index += 1;
+	}
+}
+
+fn next_paren_end(tokens: &[Token]) -> Result<usize, ParseError> {
+	let mut index = 0;
+	let mut paren_count = 0usize;
+	loop {
+		match tokens.get(index) {
+			Some(Token::Sym(Symbol::OpenParen)) => paren_count += 1,
+			Some(Token::Sym(Symbol::CloseParen)) if paren_count == 0 => return Ok(index),
+			Some(Token::Sym(Symbol::CloseParen)) => paren_count -= 1,
+			None => return Err(ParseError::new("mismatched (")),
+			_ => (),
 		}
 		index += 1;
 	}
@@ -87,26 +103,30 @@ fn parse_expr(tokens: &[Token]) -> Result<(Vec<ASTNode>, usize), ParseError> {
 	let mut ast = vec![];
 	let mut index = 0;
 	let mut op_stack: Vec<Operator> = vec![];
+	let mut unary_negate = false;
 	loop {
 		match tokens.get(index) {
 			None => {
 				while !op_stack.is_empty() {
 					ast.push(ASTNode::BinOp(op_stack.pop().unwrap()));
 				}
-				return Ok((ast, index));
+				if unary_negate && !matches!(tokens.get(index), Some(Token::Sym(Symbol::Semicolon))) {
+					ast.push(ASTNode::UnaryMinus);
 				}
+				return Ok((ast, index));
+			},
 			Some(Token::Lit(v)) => ast.push(ASTNode::Val(Value::Lit(v.clone()))),
 			Some(Token::Id(v)) => ast.push(ASTNode::Val(Value::Id(v.clone()))),
 			Some(Token::Kw(Keyword::Let)) => {
 				let id = match_or_return!(tokens.get(index + 1), Token::Id(a), a, ParseError::new("identifier expected after 'let' keyword"));
 				match_or_return!(tokens.get(index + 2), Token::Sym(Symbol::EqualSign), (), ParseError::new("= expected after identifier"));
-				let tokens = &tokens[(3 + index)..];
-				let next_end = next_expr_end(tokens);
-				let (mut expr, count) = parse_expr(&tokens[..next_end])?;
+				let stokens = &tokens[(3 + index)..];
+				let next_end = next_expr_end(stokens);
+				let (mut expr, count) = parse_expr(&stokens[..next_end])?;
 				ast.push(ASTNode::Val(Value::Id(id.to_owned())));
 				ast.append(&mut expr);
 				ast.push(ASTNode::ConstDecl);
-				index += count + 3; // 4 + count - 1
+				index += count + 2;// 4 + count - 1
 			},
 			Some(Token::Kw(Keyword::Fn)) => {
 				/*let id = match_or_return!(tokens.get(index + 1), Token::Id(a), a, ParseError::new("identifier expected after 'let' keyword"));
@@ -130,13 +150,36 @@ fn parse_expr(tokens: &[Token]) -> Result<(Vec<ASTNode>, usize), ParseError> {
 			Some(Token::Sym(Symbol::CloseBrace)) => {
 				return Err(ParseError::new("unexpected }"));
 			},
+			Some(Token::Sym(Symbol::OpenParen)) => {
+				let end = next_paren_end(&tokens[(index + 1)..])?;
+				let (expr, count) = parse_expr(&tokens[(index + 1)..(index + end + 1)])?;
+				ast.push(ASTNode::Block(expr));
+				index += count + 1;
+			},
+			Some(Token::Sym(Symbol::CloseParen)) => {
+				return Err(ParseError::new("unexpected )"));
+			},
 			Some(Token::Sym(Symbol::Semicolon)) => {
 				while !op_stack.is_empty() {
 					ast.push(ASTNode::BinOp(op_stack.pop().unwrap()));
 				}
+				// I'll macro this later
+				if unary_negate && !matches!(tokens.get(index), Some(Token::Sym(Symbol::Semicolon))) {
+					ast.push(ASTNode::UnaryMinus);
+					unary_negate = false;
+				}
 				ast.push(ASTNode::StatementEnd);
 			},
 			Some(Token::Op(op)) => {
+				if (matches!(ast.last(), Some(ASTNode::StatementEnd) | None) || !op_stack.is_empty()) && matches!(op, Operator::Minus) {
+					unary_negate = true;
+					index += 1;
+					continue;
+				}
+				if unary_negate && !matches!(tokens.get(index), Some(Token::Sym(Symbol::Semicolon))) {
+					ast.push(ASTNode::UnaryMinus);
+					unary_negate = false;
+				}
 				match op_stack.last() {
 					None => op_stack.push(op.clone()),
 					Some(last_op) if last_op.get_precedence() < op.get_precedence() => {

test.matcha

@@ -1,8 +1,8 @@
 
 let x = 5;
 let y = {
-	let x = 1;
-	x + 1
+	let x = -x;
+	x + 1 * -x
 };
 x + y