[FEAT] JSON constrained support (#1125)

Co-authored-by: Yineng Zhang <me@zhyncs.com>

python/sglang/srt/constrained/fsm_cache.py

@@ -15,6 +15,8 @@ limitations under the License.
 
 """Cache for the compressed finite state machine."""
 
+from outlines.fsm.json_schema import build_regex_from_schema
+
 from sglang.srt.constrained import RegexGuide, TransformerTokenizer
 from sglang.srt.constrained.base_tool_cache import BaseToolCache
 
@@ -26,9 +28,12 @@ class FSMCache(BaseToolCache):
         tokenizer_args_dict,
         enable=True,
         skip_tokenizer_init=False,
+        json_schema_mode=False,
     ):
         super().__init__(enable=enable)
 
+        self.json_schema_mode = json_schema_mode
+
         if (
             skip_tokenizer_init
             or tokenizer_path.endswith(".json")
@@ -72,5 +77,9 @@ class FSMCache(BaseToolCache):
                 tokenizer_path, **tokenizer_args_dict
             )
 
-    def init_value(self, regex):
-        return RegexGuide(regex, self.outlines_tokenizer)
+    def init_value(self, value):
+        if self.json_schema_mode:
+            regex = build_regex_from_schema(value)
+            return RegexGuide(regex, self.outlines_tokenizer), regex
+        else:
+            return RegexGuide(value, self.outlines_tokenizer)

python/sglang/srt/constrained/jump_forward.py

@@ -23,6 +23,7 @@ from collections import defaultdict
 
 import interegular
 import outlines.caching
+from outlines.fsm.json_schema import build_regex_from_schema
 
 from sglang.srt.constrained import (
     FSMInfo,