Factor out bash and activate files

pre_commit/languages/pcre.py

@@ -2,7 +2,7 @@ from __future__ import unicode_literals
 
 from sys import platform
 
-from pre_commit.languages.helpers import file_args_to_stdin
+from pre_commit.languages import helpers
 from pre_commit.util import shell_escape
 
 
@@ -12,29 +12,28 @@ ENVIRONMENT_DIR = None
 def install_environment(
         repo_cmd_runner,
         version='default',
-        additional_dependencies=None,
+        additional_dependencies=(),
 ):
     """Installation for pcre type is a noop."""
     raise AssertionError('Cannot install pcre repo.')
 
 
 def run_hook(repo_cmd_runner, hook, file_args):
-    grep_command = 'grep -H -n -P'
-    if platform == 'darwin':  # pragma: no cover (osx)
-        grep_command = 'ggrep -H -n -P'
+    grep_command = '{0} -H -n -P'.format(
+        'ggrep' if platform == 'darwin' else 'grep',
+    )
 
     # For PCRE the entry is the regular expression to match
-    return repo_cmd_runner.run(
-        [
-            'xargs', '-0', 'sh', '-c',
+    return helpers.run_hook(
+        (
+            'sh', '-c',
             # Grep usually returns 0 for matches, and nonzero for non-matches
             # so we flip it here.
             '! {0} {1} {2} $@'.format(
                 grep_command, ' '.join(hook['args']),
-                shell_escape(hook['entry'])),
+                shell_escape(hook['entry']),
+            ),
             '--',
-        ],
-        stdin=file_args_to_stdin(file_args),
-        retcode=None,
-        encoding=None,
+        ),
+        file_args,
     )