Implement no-dependency system and script hook types. Closes #39.

pre_commit/languages/all.py

@@ -2,6 +2,8 @@
 from pre_commit.languages import node
 from pre_commit.languages import python
 from pre_commit.languages import ruby
+from pre_commit.languages import script
+from pre_commit.languages import system
 
 # A language implements the following two functions in its module:
 #
@@ -29,4 +31,9 @@ languages = {
     'node': node,
     'python': python,
     'ruby': ruby,
+    'script': script,
+    'system': system,
 }
+
+
+all_languages = languages.keys()

pre_commit/languages/script.py

@@ -0,0 +1,13 @@
+
+def install_environment(repo_cmd_runner):
+    """Installation for script type is a noop."""
+    pass
+
+
+def run_hook(repo_cmd_runner, hook, file_args):
+    return repo_cmd_runner.run(
+        ['xargs', '{{prefix}}{0}'.format(hook['entry'])] + hook.get('args', []),
+        # TODO: this is duplicated in pre_commit/languages/helpers.py
+        stdin='\n'.join(list(file_args) + ['']),
+        retcode=None,
+    )

pre_commit/languages/system.py

@@ -0,0 +1,13 @@
+
+def install_environment(repo_cmd_runner):
+    """Installation for system type is a noop."""
+    pass
+
+
+def run_hook(repo_cmd_runner, hook, file_args):
+    return repo_cmd_runner.run(
+        ['xargs', hook['entry']] + hook.get('args', []),
+        # TODO: this is duplicated in pre_commit/languages/helpers.py
+        stdin='\n'.join(list(file_args) + ['']),
+        retcode=None,
+    )