chore: expose insert_after_imports predicate (#236)

.grit/patterns/js/imports.grit

@@ -60,24 +60,28 @@ private pattern process_one_source($p, $all_imports) {
     }
 }
 
+predicate insert_after_imports($p, $insert) {
+    or {
+        // Try to find a shebang and insert after that
+        $p <: program(hash_bang=$h) where {
+            $h <: hash_bang_line() += `\n$insert`
+        },
+        // Find an import statement to anchor on
+        $p <: program($statements) where {
+            $statements <: some $anchor where { $anchor <: import_statement() },
+            $anchor += `\n$insert`
+        },
+        // Fall back to inserting at the start of the whole program
+        $p => `$insert\n$p`
+    }
+}
+
 private pattern insert_imports() {
     $p where {
         $all_imports = [],
         $GLOBAL_IMPORTED_SOURCES <: some process_one_source($p, $all_imports),
         if ($all_imports <: not []) {
-            or {
-              // Try to find a shebang and insert after that
-              $p <: program(hash_bang=$h) where {
-                $h <: hash_bang_line() += `\n$all_imports`
-              },
-              // Find an import statement to anchor on
-              $p <: program($statements) where {
-                $statements <: some $anchor where { $anchor <: import_statement() },
-                $anchor += `\n$all_imports`
-              },
-              // Fall back to inserting the whole program
-              $p => `$all_imports\n$p`
-            }
+            insert_after_imports($p, insert=$all_imports)
         } else {
             true
         }