feat: add comprehensive GitHub workflow and development tools

app/.venv/Lib/site-packages/psycopg/_struct.py

@@ -0,0 +1,57 @@
+"""
+Utility functions to deal with binary structs.
+"""
+
+# Copyright (C) 2020 The Psycopg Team
+
+from __future__ import annotations
+
+import struct
+from typing import Callable, cast, Protocol
+
+from . import errors as e
+from .abc import Buffer
+from ._compat import TypeAlias
+
+PackInt: TypeAlias = Callable[[int], bytes]
+UnpackInt: TypeAlias = Callable[[Buffer], "tuple[int]"]
+PackFloat: TypeAlias = Callable[[float], bytes]
+UnpackFloat: TypeAlias = Callable[[Buffer], "tuple[float]"]
+
+
+class UnpackLen(Protocol):
+    def __call__(self, data: Buffer, start: int | None) -> tuple[int]: ...
+
+
+pack_int2 = cast(PackInt, struct.Struct("!h").pack)
+pack_uint2 = cast(PackInt, struct.Struct("!H").pack)
+pack_int4 = cast(PackInt, struct.Struct("!i").pack)
+pack_uint4 = cast(PackInt, struct.Struct("!I").pack)
+pack_int8 = cast(PackInt, struct.Struct("!q").pack)
+pack_float4 = cast(PackFloat, struct.Struct("!f").pack)
+pack_float8 = cast(PackFloat, struct.Struct("!d").pack)
+
+unpack_int2 = cast(UnpackInt, struct.Struct("!h").unpack)
+unpack_uint2 = cast(UnpackInt, struct.Struct("!H").unpack)
+unpack_int4 = cast(UnpackInt, struct.Struct("!i").unpack)
+unpack_uint4 = cast(UnpackInt, struct.Struct("!I").unpack)
+unpack_int8 = cast(UnpackInt, struct.Struct("!q").unpack)
+unpack_float4 = cast(UnpackFloat, struct.Struct("!f").unpack)
+unpack_float8 = cast(UnpackFloat, struct.Struct("!d").unpack)
+
+_struct_len = struct.Struct("!i")
+pack_len = cast(Callable[[int], bytes], _struct_len.pack)
+unpack_len = cast(UnpackLen, _struct_len.unpack_from)
+
+
+def pack_float4_bug_304(x: float) -> bytes:
+    raise e.InterfaceError(
+        "cannot dump Float4: Python affected by bug #304. Note that the psycopg-c"
+        " and psycopg-binary packages are not affected by this issue."
+        " See https://github.com/psycopg/psycopg/issues/304"
+    )
+
+
+# If issue #304 is detected, raise an error instead of dumping wrong data.
+if struct.Struct("!f").pack(1.0) != bytes.fromhex("3f800000"):
+    pack_float4 = pack_float4_bug_304