From aa5ca2f9a8f36fba434c28d33c67dfb25ffc86c3 Mon Sep 17 00:00:00 2001
From: Mark McCulloh <Mark.McCulloh@gmail.com>
Date: Fri, 22 Sep 2023 05:26:31 -0400
Subject: [PATCH] fix: automatically semicolon incorrectly inserted into `as`
 and `in` expressions (#4254)

Fixes #4247

*By submitting this pull request, I confirm that my contribution is made under the terms of the [Wing Cloud Contribution License](https://github.com/winglang/wing/blob/main/CONTRIBUTION_LICENSE.md)*.
---
 libs/tree-sitter-wing/src/scanner.c           | 30 +++++++++++++++++++
 .../test/corpus/expressions.txt               | 22 ++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/libs/tree-sitter-wing/src/scanner.c b/libs/tree-sitter-wing/src/scanner.c
index 87a5fca5280..02ee7e61323 100644
--- a/libs/tree-sitter-wing/src/scanner.c
+++ b/libs/tree-sitter-wing/src/scanner.c
@@ -84,6 +84,16 @@ static bool scan_whitespace_and_comments(TSLexer *lexer)
   }
 }
 
+/**
+ * Check if a character is a valid identifier character
+ *
+ * @return true if the character is a valid identifier character, false otherwise
+ */
+static bool iswidentifier(int c)
+{
+  return iswalnum(c) || c == '_';
+}
+
 /**
  * Check if an automatic semicolon could be inserted
  *
@@ -146,6 +156,26 @@ static bool scan_automatic_semicolon(TSLexer *lexer)
   case '!':
     skip(lexer);
     return lexer->lookahead != '=';
+
+  // Don't insert a semicolon before `in` (unless it's part of an identifier)
+  case 'i':
+    skip(lexer);
+    if (lexer->lookahead == 'n')
+    {
+      skip(lexer);
+      if (!iswidentifier(lexer->lookahead))
+        return false;
+    }
+  
+  // Don't insert a semicolon before `as` (unless it's part of an identifier)
+  case 'a':
+    skip(lexer);
+    if (lexer->lookahead == 's')
+    {
+      skip(lexer);
+      if (!iswidentifier(lexer->lookahead))
+        return false;
+    }
   }
 
   return true;
diff --git a/libs/tree-sitter-wing/test/corpus/expressions.txt b/libs/tree-sitter-wing/test/corpus/expressions.txt
index f04eca2346a..abddffe1961 100644
--- a/libs/tree-sitter-wing/test/corpus/expressions.txt
+++ b/libs/tree-sitter-wing/test/corpus/expressions.txt
@@ -158,6 +158,28 @@ new A() as "b" in c;
 
 --------------------------------------------------------------------------------
 
+(source
+  (expression_statement
+    (new_expression
+      class: (custom_type
+        object: (type_identifier))
+      args: (argument_list)
+      id: (string)
+      scope: (reference
+        (reference_identifier)))))
+
+================================================================================
+New expression with id and scope on different lines
+================================================================================
+
+new A()
+  as 
+  "b" 
+  in 
+  c;
+
+--------------------------------------------------------------------------------
+
 (source
   (expression_statement
     (new_expression