First commit

src/parser.rs

@@ -0,0 +1,45 @@
+use winnow::Parser;
+use winnow::ascii::multispace0;
+use winnow::combinator::{Infix, Prefix, peek};
+use winnow::combinator::{delimited, dispatch, expression, fail};
+use winnow::error::ContextError;
+use winnow::token::any;
+
+use crate::binary_repr::parse_binary_repr;
+use crate::expr::{BinOp, Expr, UnaryOp};
+
+pub fn parser<'i>(size: usize) -> impl Parser<&'i str, Expr, ContextError> {
+    move |i: &mut &str| {
+        use Infix::Left;
+        expression(delimited(
+            multispace0,
+            dispatch! {peek(any);
+                '(' => delimited('(',  parser(size).map(|e| Expr::Group(Box::new(e))), ')'),
+                _ =>                 parse_binary_repr(size).map(Expr::Constant),
+
+            },
+            multispace0,
+        ))
+        .prefix(delimited(
+            multispace0,
+            dispatch! {any;
+                '-' => Prefix(12, |_, a| Ok(Expr::UnaryOp(UnaryOp::Neg, Box::new(a)))),
+                '!' => Prefix(12, |_, a| Ok(Expr::UnaryOp(UnaryOp::Not, Box::new(a)))),
+                _ => fail,
+            },
+            multispace0,
+        ))
+        .infix(delimited(
+            multispace0,
+            dispatch! {any;
+                '+' => Left(5, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Plus, Box::new(b)))),
+                '-' => Left(5, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Sub, Box::new(b)))),
+                '*' => Left(7, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Mul, Box::new(b)))),
+                '/' => Left(7, |_, a, b| Ok(Expr::BinaryOp(Box::new(a), BinOp::Div, Box::new(b)))),
+                _ => fail,
+            },
+            multispace0,
+        ))
+        .parse_next(i)
+    }
+}