Add types to pre-commit

pre_commit/resources/hook-tmpl

@@ -4,6 +4,8 @@ import distutils.spawn
 import os
 import subprocess
 import sys
+from typing import Callable
+from typing import Dict
 from typing import Tuple
 
 # work around https://github.com/Homebrew/homebrew-core/issues/30445
@@ -28,7 +30,7 @@ class FatalError(RuntimeError):
     pass
 
 
-def _norm_exe(exe):
+def _norm_exe(exe: str) -> Tuple[str, ...]:
     """Necessary for shebang support on windows.
 
     roughly lifted from `identify.identify.parse_shebang`
@@ -47,7 +49,7 @@ def _norm_exe(exe):
         return tuple(cmd)
 
 
-def _run_legacy():
+def _run_legacy() -> Tuple[int, bytes]:
     if __file__.endswith('.legacy'):
         raise SystemExit(
             "bug: pre-commit's script is installed in migration mode\n"
@@ -59,9 +61,9 @@ def _run_legacy():
         )
 
     if HOOK_TYPE == 'pre-push':
-        stdin = getattr(sys.stdin, 'buffer', sys.stdin).read()
+        stdin = sys.stdin.buffer.read()
     else:
-        stdin = None
+        stdin = b''
 
     legacy_hook = os.path.join(HERE, f'{HOOK_TYPE}.legacy')
     if os.access(legacy_hook, os.X_OK):
@@ -73,7 +75,7 @@ def _run_legacy():
         return 0, stdin
 
 
-def _validate_config():
+def _validate_config() -> None:
     cmd = ('git', 'rev-parse', '--show-toplevel')
     top_level = subprocess.check_output(cmd).decode('UTF-8').strip()
     cfg = os.path.join(top_level, CONFIG)
@@ -97,7 +99,7 @@ def _validate_config():
         )
 
 
-def _exe():
+def _exe() -> Tuple[str, ...]:
     with open(os.devnull, 'wb') as devnull:
         for exe in (INSTALL_PYTHON, sys.executable):
             try:
@@ -117,11 +119,11 @@ def _exe():
     )
 
 
-def _rev_exists(rev):
+def _rev_exists(rev: str) -> bool:
     return not subprocess.call(('git', 'rev-list', '--quiet', rev))
 
 
-def _pre_push(stdin):
+def _pre_push(stdin: bytes) -> Tuple[str, ...]:
     remote = sys.argv[1]
 
     opts: Tuple[str, ...] = ()
@@ -158,8 +160,8 @@ def _pre_push(stdin):
         raise EarlyExit()
 
 
-def _opts(stdin):
-    fns = {
+def _opts(stdin: bytes) -> Tuple[str, ...]:
+    fns: Dict[str, Callable[[bytes], Tuple[str, ...]]] = {
         'prepare-commit-msg': lambda _: ('--commit-msg-filename', sys.argv[1]),
         'commit-msg': lambda _: ('--commit-msg-filename', sys.argv[1]),
         'pre-merge-commit': lambda _: (),
@@ -171,13 +173,14 @@ def _opts(stdin):
 
 
 if sys.version_info < (3, 7):  # https://bugs.python.org/issue25942
-    def _subprocess_call(cmd):  # this is the python 2.7 implementation
+    # this is the python 2.7 implementation
+    def _subprocess_call(cmd: Tuple[str, ...]) -> int:
         return subprocess.Popen(cmd).wait()
 else:
     _subprocess_call = subprocess.call
 
 
-def main():
+def main() -> int:
     retv, stdin = _run_legacy()
     try:
         _validate_config()