Add constrained_json_whitespace_pattern to ServerArgs (#1438)

python/sglang/srt/server_args.py

@@ -70,6 +70,7 @@ class ServerArgs:
     tp_size: int = 1
     stream_interval: int = 1
     random_seed: Optional[int] = None
+    constrained_json_whitespace_pattern: Optional[str] = None
 
     # Logging
     log_level: str = "info"
@@ -370,6 +371,12 @@ class ServerArgs:
             default=ServerArgs.random_seed,
             help="The random seed.",
         )
+        parser.add_argument(
+            "--constrained-json-whitespace-pattern",
+            type=str,
+            default=ServerArgs.constrained_json_whitespace_pattern,
+            help=r"Regex pattern for syntactic whitespaces allowed in JSON constrained output. For example, to allow the model generate consecutive whitespaces, set the pattern to [\n\t ]*",
+        )
         parser.add_argument(
             "--log-level",
             type=str,