first pass at #50 (yapf hook)

README.md

@@ -24,6 +24,8 @@ Add this to your `.pre-commit-config.yaml`
 ### Hooks available
 
 - `autopep8-wrapper` - Runs autopep8 over python source. (You'll want `args: ['-i]` when using this hook, see `.pre-commit-config.yaml` for an example.)
+- `yapf-wrapper` - Runs yapf over python source. (You'll want `args: ['-i]` when using this hook, see `.pre-commit-config.yaml` for an example.)
+  **NOTE: yapf is currently alpha and has not yet been released, so enabling this hook currently requires you to install yapf manually from source.**
 - `check-added-large-files` - Prevent giant files from being committed.
 - `check-case-conflict` - Check for files that would conflict in case-insensitive filesystems.
 - `check-docstring-first` - Checks a common error of defining a docstring after code.

hooks.yaml

@@ -1,3 +1,10 @@
+-   id: yapf-wrapper
+    name: yapf wrapper
+    description: "Runs yapf over python source. (You'll want args: [-i] when using this hook, see .pre-commit-config.yaml for an example.)"
+    entry: yapf-wrapper
+    language: python
+    files: \.py$
+    args: [-i]
 -   id: autopep8-wrapper
     name: autopep8 wrapper
     description: "Runs autopep8 over python source. (You'll want args: [-i] when using this hook, see .pre-commit-config.yaml for an example.)"

pre_commit_hooks/yapf_wrapper.py

@@ -0,0 +1,17 @@
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import io
+import sys
+
+import yapf
+
+
+def main(argv=None):
+    argv = argv if argv is not None else sys.argv[1:]
+    return yapf.main(argv)
+
+
+if __name__ == '__main__':
+    exit(main())

setup.py

@@ -33,9 +33,11 @@ setup(
         'pyflakes',
         'pyyaml',
         'simplejson',
+        # TODO: include yapf when it is released
     ],
     entry_points={
         'console_scripts': [
+            'yapf-wrapper = pre_commit_hooks.yapf_wrapper:main',
             'autopep8-wrapper = pre_commit_hooks.autopep8_wrapper:main',
             'check-added-large-files = pre_commit_hooks.check_added_large_files:main',
             'check-case-conflict = pre_commit_hooks.check_case_conflict:main',