Fix operator precedence parsing

examples/easiest.rs

@@ -1,9 +1,9 @@
 use reid::compile;
 
-pub static EASIEST: &str = include_str!("./reid/easiest.reid");
+pub static EASY: &str = include_str!("./reid/easy.reid");
 
 fn main() {
-    let text = match compile(EASIEST) {
+    let text = match compile(EASY) {
         Ok(t) => t,
         Err(e) => panic!("{}", e),
     };

examples/reid/easy.reid

@@ -3,10 +3,10 @@
 import std::print;
 
 fn main() {
-    let test = 5;
+    let test = 9;
     let simpleAdd = 2 + 2;
+    let simpleMult = 7 * 2;
     let arithmetic = 3 + 2 * 5 + 1 * 2;
-    let multiplier = 5 * 2;
 
-    return arithmetic + multiplier * arithmetic;
+    return arithmetic + simpleMult * arithmetic;
 }

src/ast.rs

@@ -46,7 +46,7 @@ pub enum Expression {
 impl Parse for Expression {
     fn parse(mut stream: TokenStream) -> Result<Expression, Error> {
         let lhs = parse_primary_expression(&mut stream)?;
-        parse_binop_rhs(&mut stream, lhs, None)
+        parse_binop_rhs(&mut stream, lhs, 0, None).map(|(rhs, _)| rhs)
     }
 }
 
@@ -81,27 +81,28 @@ fn parse_primary_expression(stream: &mut TokenStream) -> Result<Expression, Erro
 fn parse_binop_rhs(
     stream: &mut TokenStream,
     mut lhs: Expression,
+    expr_prec: i8,
     mut operator: Option<BinaryOperator>,
-) -> Result<Expression, Error> {
+) -> Result<(Expression, Option<BinaryOperator>), Error> {
-    let expr_prec = if let Some(op) = operator {
-        op.get_precedence() + 1
-    } else {
-        0
-    };
-
     while let Some(op) = operator.take().as_ref().or(stream.parse().as_ref().ok()) {
         let curr_token_prec = op.get_precedence();
 
         if curr_token_prec < expr_prec {
+            let _ = operator.insert(*op);
             break; // Just return lhs
         } else {
             let mut rhs = parse_primary_expression(stream)?;
+
             if let Ok(next_op) = stream.parse::<BinaryOperator>() {
                 let next_prec = next_op.get_precedence();
                 if curr_token_prec < next_prec {
                     // Operator on the right of rhs has more precedence, turn
                     // rhs into lhs for new binop
-                    rhs = parse_binop_rhs(stream, rhs, Some(next_op))?;
+                    let op;
+                    (rhs, op) = parse_binop_rhs(stream, rhs, curr_token_prec + 1, Some(next_op))?;
+                    if let Some(upcoming_op) = op {
+                        let _ = operator.insert(upcoming_op);
+                    }
                 } else {
                     let _ = operator.insert(next_op);
                 }
@@ -111,7 +112,7 @@ fn parse_binop_rhs(
         }
     }
 
-    Ok(lhs)
+    Ok((lhs, operator))
 }
 
 #[derive(Debug, Clone, Copy)]

src/token_stream.rs

@@ -57,7 +57,7 @@ impl<'a, 'b> TokenStream<'a, 'b> {
         }
     }
 
-    pub fn parse<T: Parse>(&mut self) -> Result<T, Error> {
+    pub fn parse<T: Parse + std::fmt::Debug>(&mut self) -> Result<T, Error> {
         let mut ref_pos = self.position;
 
         let position = self.position;
@@ -70,6 +70,7 @@ impl<'a, 'b> TokenStream<'a, 'b> {
         match T::parse(clone) {
             Ok(res) => {
                 self.position = ref_pos.max(self.position);
+                dbg!(&res);
                 Ok(res)
             }
             Err(e) => Err(e),