[Feature] support regex strings as a stopping condition (#10635)

python/sglang/srt/managers/schedule_batch.py

@@ -36,6 +36,7 @@ TODO(lmzheng): ModelWorkerBatch seems a bit redundant and we consider removing i
 import copy
 import dataclasses
 import logging
+import re
 import threading
 import time
 from enum import Enum, auto
@@ -154,6 +155,18 @@ class FINISH_MATCHED_STR(BaseFinishReason):
         }
 
 
+class FINISHED_MATCHED_REGEX(BaseFinishReason):
+    def __init__(self, matched: str):
+        super().__init__()
+        self.matched = matched
+
+    def to_json(self):
+        return {
+            "type": "stop",  # to match OpenAI API's return value
+            "matched": self.matched,
+        }
+
+
 class FINISH_LENGTH(BaseFinishReason):
     def __init__(self, length: int):
         super().__init__()
@@ -735,8 +748,17 @@ class Req:
         return self.surr_and_decode_ids, self.read_offset - self.surr_offset
 
     def tail_str(self) -> str:
-        tail_len = self.sampling_params.stop_str_max_len + 1
-        tail_len = min(tail_len, len(self.output_ids))
+        # Check stop strings and stop regex patterns together
+        if (
+            len(self.sampling_params.stop_strs) > 0
+            or len(self.sampling_params.stop_regex_strs) > 0
+        ):
+            max_len_tail_str = max(
+                self.sampling_params.stop_str_max_len + 1,
+                self.sampling_params.stop_regex_max_len + 1,
+            )
+
+        tail_len = min((max_len_tail_str + 1), len(self.output_ids))
         return self.tokenizer.decode(self.output_ids[-tail_len:])
 
     def check_match_stop_str_prefix(self) -> bool:
@@ -817,14 +839,27 @@ class Req:
             self.finished_reason = FINISH_MATCHED_STR(matched="NaN happened")
             return
 
-        # Check stop strings
-        if len(self.sampling_params.stop_strs) > 0:
+        if (
+            len(self.sampling_params.stop_strs) > 0
+            or len(self.sampling_params.stop_regex_strs) > 0
+        ):
             tail_str = self.tail_str()
 
-            for stop_str in self.sampling_params.stop_strs:
-                if stop_str in tail_str or stop_str in self.decoded_text:
-                    self.finished_reason = FINISH_MATCHED_STR(matched=stop_str)
-                    return
+            # Check stop strings
+            if len(self.sampling_params.stop_strs) > 0:
+                for stop_str in self.sampling_params.stop_strs:
+                    if stop_str in tail_str or stop_str in self.decoded_text:
+                        self.finished_reason = FINISH_MATCHED_STR(matched=stop_str)
+                        return
+
+            # Check stop regex
+            if len(self.sampling_params.stop_regex_strs) > 0:
+                for stop_regex_str in self.sampling_params.stop_regex_strs:
+                    if re.search(stop_regex_str, tail_str):
+                        self.finished_reason = FINISHED_MATCHED_REGEX(
+                            matched=stop_regex_str
+                        )
+                        return
 
     def reset_for_retract(self):
         self.prefix_indices = torch.empty((0,), dtype=torch.int64)