if conditions

crates/parser/src/lib.rs

@@ -605,7 +605,7 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> {
 
         let field = just(Token::Dot).ignore_then(select! {Token::Ident(ident) => ident});
 
-        let expr = simple.pratt((
+        let assignment_expr = simple.pratt((
             postfix(100, subscript, |expr, index, e: &mut E| {
                 let node = AstNode::Subscript { expr, index };
                 e.state().push(node)
@@ -729,6 +729,27 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> {
             }),
         ));
 
+        let else_expr = just(Token::Else).ignore_then(_expr.clone());
+
+        let if_expr = just(Token::If)
+            .ignore_then(
+                _expr
+                    .clone()
+                    .delimited_by(just(Token::OpenParens), just(Token::CloseParens)),
+            )
+            .then(_expr.clone())
+            .then(else_expr.or_not())
+            .map_with(|((condition, then), r#else), e: &mut E| {
+                let node = AstNode::If {
+                    condition,
+                    then,
+                    r#else,
+                };
+                e.state().push(node)
+            });
+
+        let expr = choice((if_expr, assignment_expr)).labelled("expression");
+
         Arc::new(expr)
     })
 }