Lex & parse function call

src/ast.rs

@@ -82,6 +82,8 @@ pub enum Expression {
     I64(i64),
     /// String literal
     String(Rc<String>),
+
+    FunCall(String, Vec<Expression>),
     /// Variable
     Var(String),
     /// Binary operation. Consists of type, left hand side and right hand side
@@ -116,6 +118,7 @@ pub enum Statement {
     Loop(Loop),
     If(If),
     Print(Expression),
+    FunDecl(Vec<(String, Expression)>),
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Default)]

src/interpreter.rs

@@ -68,6 +68,7 @@ impl Interpreter {
                         self.run(body_true);
                     }
                 }
+                Statement::FunDecl(_) => todo!(),
             }
 
         }
@@ -80,6 +81,7 @@ impl Interpreter {
             Expression::BinOp(bo, lhs, rhs) => self.resolve_binop(bo, lhs, rhs),
             Expression::UnOp(uo, operand) => self.resolve_unop(uo, operand),
             Expression::Var(name) => self.resolve_var(name),
+            Expression::FunCall(_, _) => todo!(),
         }
     }
 

src/lexer.rs

@@ -106,6 +106,7 @@ impl<'a> Lexer<'a> {
                 '{' => tokens.push(Token::LBraces),
                 '}' => tokens.push(Token::RBraces),
                 '!' => tokens.push(Token::LNot),
+                ',' => tokens.push(Token::Comma),
 
                 // Lex numbers
                 ch @ '0'..='9' => {
@@ -189,6 +190,7 @@ impl<'a> Lexer<'a> {
                         "print" => Token::Print,
                         "if" => Token::If,
                         "else" => Token::Else,
+                        "fun" => Token::Fun,
 
                         // If it doesn't match a keyword, it is a normal identifier
                         _ => Token::Ident(ident),

src/parser.rs

@@ -1,7 +1,7 @@
 use std::iter::Peekable;
 
-use crate::token::Token;
 use crate::ast::*;
+use crate::token::Token;
 
 struct Parser<T: Iterator<Item = Token>> {
     tokens: Peekable<T>,
@@ -28,14 +28,11 @@ impl<T: Iterator<Item = Token>> Parser<T> {
                 }
 
                 // By default try to lex a statement
-                _ => {
-                    prog.push(self.parse_stmt())
-                }
+                _ => prog.push(self.parse_stmt()),
             }
         }
 
         Ast { prog }
-
     }
 
     fn parse_stmt(&mut self) -> Statement {
@@ -104,7 +101,11 @@ impl<T: Iterator<Item = Token>> Parser<T> {
             }
         }
 
-        If { condition, body_true, body_false }
+        If {
+            condition,
+            body_true,
+            body_false,
+        }
     }
 
     fn parse_loop(&mut self) -> Loop {
@@ -130,17 +131,20 @@ impl<T: Iterator<Item = Token>> Parser<T> {
                 }
 
                 body = self.parse();
-            },
+            }
 
-            _ => panic!("Error lexing loop: Expected ';' or '{{'")
+            _ => panic!("Error lexing loop: Expected ';' or '{{'"),
         }
 
         if !matches!(self.next(), Token::RBraces) {
             panic!("Error lexing loop: Expected '}}'")
         }
 
-        Loop { condition, advancement, body }
-
+        Loop {
+            condition,
+            advancement,
+            body,
+        }
     }
 
     fn parse_expr(&mut self) -> Expression {
@@ -185,6 +189,8 @@ impl<T: Iterator<Item = Token>> Parser<T> {
             // Literal String
             Token::String(text) => Expression::String(text.into()),
 
+            Token::Ident(name) if matches!(self.peek(), Token::LParen) => self.parse_funcall(name),
+
             Token::Ident(name) => Expression::Var(name),
 
             // Parentheses grouping
@@ -221,6 +227,24 @@ impl<T: Iterator<Item = Token>> Parser<T> {
         }
     }
 
+    fn parse_funcall(&mut self, name: String) -> Expression {
+        let mut args = Vec::new();
+
+        // Consume (
+        self.next();
+
+        while self.peek() != &Token::RParen {
+            args.push(self.parse_expr());
+
+            if self.peek() == &Token::Comma {
+                self.next();
+            }
+        }
+        self.next();
+
+        Expression::FunCall(name, args)
+    }
+
     /// Get the next Token without removing it
     fn peek(&mut self) -> &Token {
         self.tokens.peek().unwrap_or(&Token::EoF)
@@ -265,8 +289,11 @@ impl BinOpType {
 
 #[cfg(test)]
 mod tests {
-    use super::{parse, Expression, BinOpType};
-    use crate::{token::Token, parser::{Statement, Ast}};
+    use super::{parse, BinOpType, Expression};
+    use crate::{
+        parser::{Ast, Statement},
+        token::Token,
+    };
 
     #[test]
     fn test_parser() {
@@ -288,13 +315,20 @@ mod tests {
             Expression::BinOp(
                 BinOpType::Add,
                 Expression::I64(1).into(),
-                Expression::BinOp(BinOpType::Mul, Expression::I64(2).into(), Expression::I64(3).into()).into(),
+                Expression::BinOp(
+                    BinOpType::Mul,
+                    Expression::I64(2).into(),
+                    Expression::I64(3).into(),
+                )
+                .into(),
             )
             .into(),
             Expression::I64(4).into(),
         ));
 
-        let expected = Ast { prog: vec![expected] };
+        let expected = Ast {
+            prog: vec![expected],
+        };
 
         let actual = parse(tokens);
         assert_eq!(expected, actual);

src/token.rs

@@ -23,6 +23,10 @@ pub enum Token {
     /// Else keyword (else)
     Else,
 
+    Fun,
+
+    Comma,
+
     /// Left Parenthesis ('(')
     LParen,