Improve parsing related to missing brackets

Author: vascocosta

src/parser.rs

@@ -69,6 +69,22 @@ impl Parser {
         }
     }
 
+    fn expect_end(&mut self, expected: &Token, label: &str) -> Result<Spanned<Token>, ParseError> {
+        let at = self
+            .tokens
+            .get(self.pos.wrapping_sub(1))
+            .map(|t| Span::point(t.span.end))
+            .unwrap_or(Span::point(0));
+        match self.peek() {
+            Some(s) if &s.token == expected => {
+                let out = s.clone();
+                self.pos += 1;
+                Ok(out)
+            }
+            _ => Err(self.err(format!("expected {}", label), Some(at))),
+        }
+    }
+
     fn with_context<R>(
         &mut self,
         ctx: &'static str,
@@ -322,7 +338,7 @@ impl Parser {
                 }
             }
 
-            p.expect(&Token::RParen, "')'")?;
+            p.expect_end(&Token::RParen, "')'")?;
 
             p.expect(&Token::LBrace, "'{'")?;
 
@@ -377,7 +393,7 @@ impl Parser {
                 }
             }
 
-            p.expect(&Token::RParen, "')'")?;
+            p.expect_end(&Token::RParen, "')'")?;
 
             Ok(args)
         })
@@ -393,7 +409,7 @@ impl Parser {
 
                     let index = self.parse_expr(0)?;
 
-                    self.expect(&Token::RBracket, "']'")?;
+                    self.expect_end(&Token::RBracket, "']'")?;
 
                     left = Expr::Index {
                         target: Box::new(left),
@@ -515,7 +531,7 @@ impl Parser {
                 ..
             }) => {
                 let expr = self.parse_expr(0)?;
-                self.expect(&Token::RParen, "')'")?;
+                self.expect_end(&Token::RParen, "')'")?;
                 Ok(expr)
             }
 
@@ -537,7 +553,7 @@ impl Parser {
                     }
                 }
 
-                p.expect(&Token::RBracket, "']'")?;
+                p.expect_end(&Token::RBracket, "']'")?;
 
                 Ok(Expr::ListLiteral(elements))
             }),
@@ -566,7 +582,7 @@ impl Parser {
                     }
                 }
 
-                p.expect(&Token::RBrace, "'}'")?;
+                p.expect_end(&Token::RBrace, "'}'")?;
 
                 Ok(Expr::RecordLiteral(fields))
             }),
@@ -590,7 +606,7 @@ impl Parser {
                     }
                 }
 
-                p.expect(&Token::RParen, "')'")?;
+                p.expect_end(&Token::RParen, "')'")?;
                 p.expect(&Token::LBrace, "'{'")?;
 
                 let mut body = Vec::new();