From 6807779a923234c829ec119da21d58e0c9ec9e64 Mon Sep 17 00:00:00 2001
From: Felipe Coury <felipe.coury@gmail.com>
Date: Tue, 17 Sep 2024 23:15:53 -0300
Subject: [PATCH] feat: parser binary operations

---
 core/src/ir.rs        |   1 +
 core/src/parser.rs    | 125 +++++++++++++++++++++++++++++++++++++++++-
 samples/operators.prg |   4 ++
 3 files changed, 128 insertions(+), 2 deletions(-)
 create mode 100644 samples/operators.prg

diff --git a/core/src/ir.rs b/core/src/ir.rs
index f137cd5..a4a424f 100644
--- a/core/src/ir.rs
+++ b/core/src/ir.rs
@@ -91,6 +91,7 @@ pub fn emit_ir(
             result
         }
         Exp::Unary(_, _) => todo!(),
+        Exp::Binary(_, _, _) => todo!(),
     };
 
     Ok(val)
diff --git a/core/src/parser.rs b/core/src/parser.rs
index e771245..3795d41 100644
--- a/core/src/parser.rs
+++ b/core/src/parser.rs
@@ -24,6 +24,44 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_exp(&mut self) -> anyhow::Result<Exp> {
+        let left = self.parse_lhs()?;
+
+        if let Some(op) = self.parse_binary_operator()? {
+            let right = self.parse_exp()?;
+            return Ok(Exp::Binary(Box::new(left), op, Box::new(right)));
+        }
+
+        Ok(left)
+    }
+
+    fn parse_binary_operator(&mut self) -> anyhow::Result<Option<BinaryOperator>> {
+        let res = match self.peek_token() {
+            Some(Token::Plus) => Some(BinaryOperator::Add),
+            Some(Token::Minus) => Some(BinaryOperator::Subtract),
+            Some(Token::Star) => Some(BinaryOperator::Multiply),
+            Some(Token::Slash) => Some(BinaryOperator::Divide),
+            Some(Token::StarStar) => Some(BinaryOperator::Exponent),
+            Some(Token::Percent) => Some(BinaryOperator::Modulo),
+            Some(Token::And) => Some(BinaryOperator::And),
+            Some(Token::Or) => Some(BinaryOperator::Or),
+            Some(Token::Less) => Some(BinaryOperator::LessThan),
+            Some(Token::LessEqual) => Some(BinaryOperator::LessThanEqual),
+            Some(Token::Greater) => Some(BinaryOperator::GreaterThan),
+            Some(Token::GreaterEqual) => Some(BinaryOperator::GreaterThanEqual),
+            Some(Token::LessGreater) | Some(Token::BangEqual) | Some(Token::Hash) => {
+                Some(BinaryOperator::NotEqual)
+            }
+            _ => None,
+        };
+
+        if res.is_some() {
+            self.take_token()?;
+        }
+
+        Ok(res)
+    }
+
+    fn parse_lhs(&mut self) -> anyhow::Result<Exp> {
         let exp = match self.peek_token() {
             Some(Token::Identifier(name)) => {
                 self.take_token()?; // consumes identifier
@@ -40,7 +78,7 @@ impl<'a> Parser<'a> {
                 Exp::Constant(n)
             }
             Some(_) => {
-                self.parse_unary()?
+                self.parse_unary_prefix()?
                 // anyhow::bail!("Expected expression, found {token:?}");
             }
             None => {
@@ -75,9 +113,15 @@ impl<'a> Parser<'a> {
         Ok(Exp::FunCall(name, args))
     }
 
-    fn parse_unary(&mut self) -> anyhow::Result<Exp> {
+    fn parse_unary_prefix(&mut self) -> anyhow::Result<Exp> {
         let operator = match self.next_token()? {
             Some(Token::Not) => UnaryOperator::Not,
+            Some(Token::And) => UnaryOperator::And,
+            Some(Token::Plus) => UnaryOperator::Positive,
+            Some(Token::Minus) => UnaryOperator::Negative,
+            Some(Token::PlusPlus) => UnaryOperator::Increment,
+            Some(Token::MinusMinus) => UnaryOperator::Decrement,
+            Some(Token::At) => UnaryOperator::Ref,
             Some(token) => {
                 return Err(anyhow::anyhow!(
                     "Expected unary operator, found {:?}",
@@ -150,11 +194,45 @@ pub enum Exp {
     Assignment(Box<Exp>, Box<Exp>),
     FunCall(String, Vec<Exp>),
     Unary(UnaryOperator, Box<Exp>),
+    Binary(Box<Exp>, BinaryOperator, Box<Exp>),
 }
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum UnaryOperator {
     Not,
+    And,
+    Positive,
+    Negative,
+    Increment,
+    Decrement,
+    Ref,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum BinaryOperator {
+    Add,
+    Subtract,
+    Multiply,
+    Divide,
+    Exponent,
+    Modulo,
+
+    And,
+    Or,
+
+    LessThan,
+    LessThanEqual,
+    GreaterThan,
+    GreaterThanEqual,
+    Equal,
+    NotEqual,
+
+    // TODO: implement those
+    SimpleAssign,
+    CompoundAssign,
+    SubstringComparison,
+    AliasAssignment,
+    Send,
 }
 
 #[cfg(test)]
@@ -163,6 +241,49 @@ mod tests {
 
     use super::*;
 
+    #[test]
+    fn binary_subtraction() {
+        let program = r#"nVar2 := 10 - nVar1"#;
+        let mut lexer = Lexer::new(program);
+        let tokens = lexer.tokenize().unwrap();
+        let mut parser = Parser::new(&tokens);
+        let program = parser.parse().unwrap();
+
+        assert_eq!(
+            program,
+            Program {
+                statements: vec![Statement::Expression(Exp::Assignment(
+                    Box::new(Exp::Var("nVar2".into())),
+                    Box::new(Exp::Binary(
+                        Box::new(Exp::Constant(10)),
+                        BinaryOperator::Subtract,
+                        Box::new(Exp::Var("nVar1".into()),)
+                    ))
+                ))]
+            }
+        );
+    }
+
+    #[test]
+    fn binary_add() {
+        let program = r#"2 + 3"#;
+        let mut lexer = Lexer::new(program);
+        let tokens = lexer.tokenize().unwrap();
+        let mut parser = Parser::new(&tokens);
+        let program = parser.parse().unwrap();
+
+        assert_eq!(
+            program,
+            Program {
+                statements: vec![Statement::Expression(Exp::Binary(
+                    Box::new(Exp::Constant(2)),
+                    BinaryOperator::Add,
+                    Box::new(Exp::Constant(3)),
+                ))]
+            }
+        );
+    }
+
     #[test]
     fn unary_not() {
         let program = r#".NOT. a"#;
diff --git a/samples/operators.prg b/samples/operators.prg
new file mode 100644
index 0000000..0b90856
--- /dev/null
+++ b/samples/operators.prg
@@ -0,0 +1,4 @@
+nVar1 := 2 + 2
+nVar2 := 10 - nVar1
+nVar3 := -nVar1
+nVar4 := ++nVar2