#9 - add prefix ops to parser

danilopedraza · Feb 7, 2024 · 87ca23e · 87ca23e
1 parent 5233947
commit 87ca23e
Show file tree

Hide file tree

Showing 3 changed files with 56 additions and 0 deletions.
diff --git a/src/eval.rs b/src/eval.rs
@@ -73,6 +73,7 @@ pub fn eval(node: &ASTNode) -> Type {
         ASTNode::Tuple(_) => todo!(),
         ASTNode::Signature(_, _) => todo!(),
         ASTNode::Infix(op, lhs, rhs) => infix(*op, eval(lhs), eval(rhs)),
+        ASTNode::Prefix(_, _) => todo!(),
     }
 }
 

diff --git a/src/lexer.rs b/src/lexer.rs
@@ -4,6 +4,7 @@ use std::{iter::Peekable, str::Chars, vec};
 pub enum Token {
     Arrow,
     Assign,
+    Bang,
     BitwiseAnd,
     BitwiseOr,
     BitwiseXor,
@@ -32,6 +33,7 @@ pub enum Token {
     RightShift,
     Rparen,
     Over,
+    Tilde,
     Times,
     ToThe,
     True,
@@ -53,6 +55,7 @@ impl Iterator for Lexer<'_> {
                 self.next()
             }
             Some(chr) => Some(match chr {
+                '!' => Token::Bang,
                 '^' => Token::BitwiseXor,
                 ',' => Token::Comma,
                 '.' => Token::Dot,
@@ -77,6 +80,7 @@ impl Iterator for Lexer<'_> {
                 '*' => self.stars(),
                 '}' => Token::Rbrace,
                 ')' => Token::Rparen,
+                '~' => Token::Tilde,
                 '0'..='9' => self.integer(chr),
                 chr if chr.is_alphabetic() => self.identifier_or_keyword(chr),
                 _ => Token::Unknown,

diff --git a/src/parser.rs b/src/parser.rs
@@ -16,6 +16,7 @@ enum Precedence {
     Multiplication,
     Exponentiation,
     Correspondence,
+    Highest,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -95,6 +96,24 @@ impl InfixOperator {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum PrefixOperator {
+    BitwiseNot,
+    LogicNot,
+    Minus,
+}
+
+impl PrefixOperator {
+    fn from(tok: Token) -> Option<Self> {
+        match tok {
+            Token::Bang => Some(Self::LogicNot),
+            Token::Minus => Some(Self::Minus),
+            Token::Tilde => Some(Self::BitwiseNot),
+            _ => None,
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum ASTNode {
     Boolean(bool),
@@ -103,6 +122,7 @@ pub enum ASTNode {
     Infix(InfixOperator, Box<ASTNode>, Box<ASTNode>),
     Integer(String),
     Let(Box<ASTNode>, Vec<ASTNode>, Box<ASTNode>),
+    Prefix(PrefixOperator, Box<ASTNode>),
     Signature(Box<ASTNode>, Option<Box<ASTNode>>),
     Symbol(String),
     Tuple(Vec<ASTNode>),
@@ -238,6 +258,9 @@ impl<T: Iterator<Item = Token>> Parser<T> {
                 Token::Lbrace => self.set(),
                 Token::Integer(int) => Ok(ASTNode::Integer(int)),
                 Token::Ident(literal) => Ok(ASTNode::Symbol(literal)),
+                tok if PrefixOperator::from(tok.clone()).is_some() => {
+                    self.prefix(PrefixOperator::from(tok).unwrap())
+                }
                 tok => Err(ParserError::UnexpectedTokenError(
                     vec![
                         Token::Lparen,
@@ -268,6 +291,11 @@ impl<T: Iterator<Item = Token>> Parser<T> {
             .and_then(|tok| InfixOperator::from(tok.clone()))
     }
 
+    fn prefix(&mut self, op: PrefixOperator) -> NodeResult {
+        self.expression(Precedence::Highest)
+            .map(|expr| ASTNode::Prefix(op, Box::new(expr)))
+    }
+
     fn parenthesis(&mut self) -> NodeResult {
         if matches!(self.tokens.peek(), Some(&Token::Rparen)) {
             self.tokens.next();
@@ -814,4 +842,27 @@ mod tests {
             ])))
         );
     }
+
+    #[test]
+    fn prefixes() {
+        let lexer = build_lexer("!(~1 - -1)");
+
+        assert_eq!(
+            parser_from(lexer).next(),
+            Some(Ok(ASTNode::Prefix(
+                PrefixOperator::LogicNot,
+                Box::new(ASTNode::Infix(
+                    InfixOperator::Substraction,
+                    Box::new(ASTNode::Prefix(
+                        PrefixOperator::BitwiseNot,
+                        Box::new(ASTNode::Integer(String::from("1"))),
+                    )),
+                    Box::new(ASTNode::Prefix(
+                        PrefixOperator::Minus,
+                        Box::new(ASTNode::Integer(String::from("1"))),
+                    )),
+                ))
+            )))
+        );
+    }
 }