Restore FSM interface for backward compatibility

outlines/fsm/fsm.py

@@ -0,0 +1,69 @@
+import warnings
+from typing import TYPE_CHECKING, List, NewType
+
+from outlines.fsm.guide import CFGGuide, RegexGuide, StopAtEOSGuide
+
+if TYPE_CHECKING:
+    from outlines.models.tokenizer import Tokenizer
+
+FSMState = NewType("FSMState", int)
+
+
+class StopAtEosFSM(StopAtEOSGuide):
+    """FSM to generate text until EOS has been generated."""
+
+    def __init__(self, tokenizer: "Tokenizer"):
+        warnings.warn(
+            UserWarning(
+                "The `StopAtTokenFSM` interface is deprecated and will be removed on 2024-06-01. Please use `StopAtEOSGuide` instead."
+            )
+        )
+        super().__init__(tokenizer)
+
+    def allowed_token_ids(self, state: FSMState) -> List[int]:
+        next_instruction = self.get_next_instruction(state)
+        return next_instruction.tokens
+
+    def next_state(self, state: FSMState, token_id: int) -> FSMState:
+        return FSMState(self.get_next_state(state, token_id))
+
+
+class RegexFSM(RegexGuide):
+    """FSM to generate text that is in the language of a regular expression."""
+
+    def __init__(self, regex_string: str, tokenizer):
+        warnings.warn(
+            UserWarning(
+                "The `RegexFSM` interface is deprecated and will be removed on 2024-06-01. Please use `RegexGuide` instead."
+            )
+        )
+        super().__init__(regex_string, tokenizer)
+
+    def allowed_token_ids(self, state: FSMState) -> List[int]:
+        next_instruction = self.get_next_instruction(state)
+        return next_instruction.tokens
+
+    def next_state(self, state: FSMState, token_id: int) -> FSMState:
+        return FSMState(self.get_next_state(state, token_id))
+
+
+class CFGFSM(CFGGuide):
+    """FSM to generate text that is in the language of a context-free grammar."""
+
+    def __init__(self, cfg_string: str, tokenizer):
+        warnings.warn(
+            UserWarning(
+                "The `CFGFSM` interface is deprecated and will be removed on 2024-06-01. Please use `CFGGuide` instead."
+            )
+        )
+        super().__init__(cfg_string, tokenizer)
+
+    def allowed_token_ids(self, state: FSMState) -> List[int]:
+        return self.get_next_instruction(state).tokens
+
+    def next_state(self, state: FSMState, token_id: int) -> FSMState:
+        return FSMState(self.get_next_state(state, token_id))
+
+    def copy(self) -> "CFGFSM":
+        """Create a copy of the FSM."""
+        return CFGFSM(self.cfg_string, self.tokenizer)