Use ggrep instead of grep for pcre on mac os

pre_commit/languages/pcre.py

@@ -1,5 +1,7 @@
 from __future__ import unicode_literals
 
+from sys import platform
+
 from pre_commit.languages.helpers import file_args_to_stdin
 from pre_commit.util import shell_escape
 
@@ -13,13 +15,17 @@ def install_environment(repo_cmd_runner, version='default'):
 
 
 def run_hook(repo_cmd_runner, hook, file_args):
+    grep_command = 'grep -H -n -P'
+    if platform == 'darwin':
+        grep_command = 'ggrep -H -n -P'
+
     # For PCRE the entry is the regular expression to match
     return repo_cmd_runner.run(
         [
             'xargs', '-0', 'sh', '-c',
             # Grep usually returns 0 for matches, and nonzero for non-matches
             # so we flip it here.
-            '! grep -H -n -P {0} $@'.format(shell_escape(hook['entry'])),
+            '! {0} {1} $@'.format(grep_command, shell_escape(hook['entry'])),
             '--',
         ],
         stdin=file_args_to_stdin(file_args),