From 3ad915cafd8b0726460078720c40d2c589d98c30 Mon Sep 17 00:00:00 2001
From: rvcas <x@rvcas.dev>
Date: Mon, 3 Oct 2022 17:00:26 -0400
Subject: [PATCH] fix: list spread allowing no comma before spread

---
 crates/lang/src/lexer.rs  |  2 +-
 crates/lang/src/parser.rs | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/crates/lang/src/lexer.rs b/crates/lang/src/lexer.rs
index 75d2ddba..431b532f 100644
--- a/crates/lang/src/lexer.rs
+++ b/crates/lang/src/lexer.rs
@@ -8,7 +8,7 @@ pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = ParseError> {
     let op = choice((
         just("==").to(Token::EqualEqual),
         just('=').to(Token::Equal),
-        just("..").to(Token::Dot),
+        just("..").to(Token::DotDot),
         just('.').to(Token::Dot),
         just("!=").to(Token::NotEqual),
         just('!').to(Token::Bang),
diff --git a/crates/lang/src/parser.rs b/crates/lang/src/parser.rs
index ce91c04c..bbbf04eb 100644
--- a/crates/lang/src/parser.rs
+++ b/crates/lang/src/parser.rs
@@ -326,13 +326,16 @@ pub fn expr_parser(
             });
 
         let list_parser = just(Token::LeftSquare)
-            .ignore_then(r.clone().separated_by(just(Token::Comma)).allow_trailing())
-            .then(
-                just(Token::DotDot)
-                    .ignore_then(r.clone())
-                    .map(Box::new)
-                    .or_not(),
-            )
+            .ignore_then(r.clone().separated_by(just(Token::Comma)))
+            .then(choice((
+                just(Token::Comma).ignore_then(
+                    just(Token::DotDot)
+                        .ignore_then(r.clone())
+                        .map(Box::new)
+                        .or_not(),
+                ),
+                just(Token::Comma).ignored().or_not().map(|_| None),
+            )))
             .then_ignore(just(Token::RightSquare))
             // TODO: check if tail.is_some and elements.is_empty then return ListSpreadWithoutElements error
             .map_with_span(|(elements, tail), span| expr::UntypedExpr::List {