Add pcre type.

pre_commit/languages/all.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 from pre_commit.languages import node
+from pre_commit.languages import pcre
 from pre_commit.languages import python
 from pre_commit.languages import ruby
 from pre_commit.languages import script
@@ -36,6 +37,7 @@ from pre_commit.languages import system
 
 languages = {
     'node': node,
+    'pcre': pcre,
     'python': python,
     'ruby': ruby,
     'script': script,

pre_commit/languages/helpers.py

@@ -1,10 +1,14 @@
 from __future__ import unicode_literals
 
 
+def file_args_to_stdin(file_args):
+    return '\n'.join(list(file_args) + [''])
+
+
 def run_hook(env, hook, file_args):
     return env.run(
         ' '.join(['xargs', hook['entry']] + hook['args']),
-        stdin='\n'.join(list(file_args) + ['']),
+        stdin=file_args_to_stdin(file_args),
         retcode=None,
     )
 

pre_commit/languages/pcre.py

@@ -0,0 +1,27 @@
+from __future__ import unicode_literals
+
+from pre_commit.languages.helpers import file_args_to_stdin
+from pre_commit.util import shell_escape
+
+
+ENVIRONMENT_DIR = None
+
+
+def install_environment(repo_cmd_runner, version='default'):
+    """Installation for pcre type is a noop."""
+    raise AssertionError('Cannot install pcre repo.')
+
+
+def run_hook(repo_cmd_runner, hook, file_args):
+    # For PCRE the entry is the regular expression to match
+    return repo_cmd_runner.run(
+        [
+            'xargs', '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'])),
+            '--',
+        ],
+        stdin=file_args_to_stdin(file_args),
+        retcode=None,
+    )

pre_commit/languages/script.py

@@ -1,16 +1,20 @@
 from __future__ import unicode_literals
 
+from pre_commit.languages.helpers import file_args_to_stdin
+
+
 ENVIRONMENT_DIR = None
 
 
 def install_environment(repo_cmd_runner, version='default'):
     """Installation for script type is a noop."""
+    raise AssertionError('Cannot install script repo.')
 
 
 def run_hook(repo_cmd_runner, hook, file_args):
     return repo_cmd_runner.run(
         ['xargs', '{{prefix}}{0}'.format(hook['entry'])] + hook['args'],
         # TODO: this is duplicated in pre_commit/languages/helpers.py
-        stdin='\n'.join(list(file_args) + ['']),
+        stdin=file_args_to_stdin(file_args),
         retcode=None,
     )

pre_commit/languages/system.py

@@ -2,18 +2,20 @@ from __future__ import unicode_literals
 
 import shlex
 
+from pre_commit.languages.helpers import file_args_to_stdin
+
 
 ENVIRONMENT_DIR = None
 
 
 def install_environment(repo_cmd_runner, version='default'):
     """Installation for system type is a noop."""
+    raise AssertionError('Cannot install system repo.')
 
 
 def run_hook(repo_cmd_runner, hook, file_args):
     return repo_cmd_runner.run(
         ['xargs'] + shlex.split(hook['entry']) + hook['args'],
-        # TODO: this is duplicated in pre_commit/languages/helpers.py
-        stdin='\n'.join(list(file_args) + ['']),
+        stdin=file_args_to_stdin(file_args),
         retcode=None,
     )

pre_commit/util.py

@@ -49,7 +49,10 @@ def clean_path_on_failure(path):
         raise
 
 
-# TODO: asottile.contextlib this with a forward port of nested
 @contextlib.contextmanager
 def noop_context():
     yield
+
+
+def shell_escape(arg):
+    return "'" + arg.replace("'", "'\"'\"'".strip()) + "'"