Add string.templatelib in 3.14 (python#14044)

Author: sobolevn

stdlib/@tests/stubtest_allowlists/py314.txt

@@ -111,7 +111,6 @@ sre_compile.CH_NEGATE
 sre_constants.CH_NEGATE
 sre_parse.CH_NEGATE
 string.Template.flags
-string.templatelib
 sys.is_remote_debug_enabled
 sys.remote_exec
 tarfile.TarFile.zstopen

stdlib/VERSIONS

@@ -283,6 +283,7 @@ ssl: 3.0-
 stat: 3.0-
 statistics: 3.4-
 string: 3.0-
+string.templatelib: 3.14-
 stringprep: 3.0-
 struct: 3.0-
 subprocess: 3.0-

stdlib/string.pyi renamed to stdlib/string/__init__.pyi

@@ -0,0 +1,28 @@
+from collections.abc import Iterator
+from typing import Any, Literal, final
+
+__all__ = ["Interpolation", "Template"]
+
+@final
+class Template:  # TODO: consider making `Template` generic on `TypeVarTuple`
+    strings: tuple[str, ...]
+    interpolations: tuple[Interpolation, ...]
+
+    def __new__(cls, *args: str | Interpolation) -> Template: ...
+    def __iter__(self) -> Iterator[str | Interpolation]: ...
+    def __add__(self, other: Template | str) -> Template: ...
+    @property
+    def values(self) -> tuple[Any, ...]: ...  # Tuple of interpolation values, which can have any type
+
+@final
+class Interpolation:
+    value: Any  # TODO: consider making `Interpolation` generic in runtime
+    expression: str
+    conversion: Literal["a", "r", "s"] | None
+    format_spec: str
+
+    __match_args__ = ("value", "expression", "conversion", "format_spec")
+
+    def __new__(
+        cls, value: Any, expression: str, conversion: Literal["a", "r", "s"] | None = None, format_spec: str = ""
+    ) -> Interpolation: ...