Overload Variables class for better typing experience

Author: tchalupnik

Diff for: src/prompt_toolkit/contrib/regular_languages/compiler.py

@@ -42,7 +42,7 @@
 from __future__ import annotations
 
 import re
-from typing import Callable, Dict, Iterable, Iterator, Pattern
+from typing import Callable, Dict, Iterable, Iterator, Pattern, TypeVar, overload
 from typing import Match as RegexMatch
 
 from .regex_parser import (
@@ -57,9 +57,7 @@
     tokenize_regex,
 )
 
-__all__ = [
-    "compile",
-]
+__all__ = ["compile", "Match", "Variables"]
 
 
 # Name of the named group in the regex, matching trailing input.
@@ -491,6 +489,9 @@ def end_nodes(self) -> Iterable[MatchVariable]:
                 yield MatchVariable(varname, value, (reg[0], reg[1]))
 
 
+_T = TypeVar("_T")
+
+
 class Variables:
     def __init__(self, tuples: list[tuple[str, str, tuple[int, int]]]) -> None:
         #: List of (varname, value, slice) tuples.
@@ -502,7 +503,13 @@ def __repr__(self) -> str:
             ", ".join(f"{k}={v!r}" for k, v, _ in self._tuples),
         )
 
-    def get(self, key: str, default: str | None = None) -> str | None:
+    @overload
+    def get(self, key: str) -> str | None: ...
+
+    @overload
+    def get(self, key: str, default: _T = None) -> str | _T: ...
+
+    def get(self, key: str, default: _T = None) -> str | _T:
         items = self.getall(key)
         return items[0] if items else default