Add support for meta hooks

pre_commit/clientlib.py

@@ -98,6 +98,8 @@ def validate_manifest_main(argv=None):
 
 
 _LOCAL_SENTINEL = 'local'
+_META_SENTINEL = 'meta'
+
 CONFIG_HOOK_DICT = schema.Map(
     'Hook', 'id',
 
@@ -121,7 +123,8 @@ CONFIG_REPO_DICT = schema.Map(
 
     schema.Conditional(
         'sha', schema.check_string,
-        condition_key='repo', condition_value=schema.Not(_LOCAL_SENTINEL),
+        condition_key='repo',
+        condition_value=schema.NotIn((_LOCAL_SENTINEL, _META_SENTINEL)),
         ensure_absent=True,
     ),
 )
@@ -138,6 +141,10 @@ def is_local_repo(repo_entry):
     return repo_entry['repo'] == _LOCAL_SENTINEL
 
 
+def is_meta_repo(repo_entry):
+    return repo_entry['repo'] == _META_SENTINEL
+
+
 class InvalidConfigError(FatalError):
     pass
 

pre_commit/repository.py

@@ -5,6 +5,7 @@ import json
 import logging
 import os
 import shutil
+import sys
 from collections import defaultdict
 
 import pkg_resources
@@ -14,6 +15,7 @@ import pre_commit.constants as C
 from pre_commit import five
 from pre_commit import git
 from pre_commit.clientlib import is_local_repo
+from pre_commit.clientlib import is_meta_repo
 from pre_commit.clientlib import MANIFEST_HOOK_DICT
 from pre_commit.languages.all import languages
 from pre_commit.languages.helpers import environment_dir
@@ -128,6 +130,8 @@ class Repository(object):
     def create(cls, config, store):
         if is_local_repo(config):
             return LocalRepository(config, store)
+        elif is_meta_repo(config):
+            return MetaRepository(config, store)
         else:
             return cls(config, store)
 
@@ -242,6 +246,45 @@ class LocalRepository(Repository):
         return tuple(ret)
 
 
+class MetaRepository(LocalRepository):
+    meta_hooks = {
+        'test-hook': {
+            'name': 'Test Hook',
+            'files': '',
+            'language': 'system',
+            'entry': 'echo "Hello World!"',
+            'always_run': True,
+        },
+    }
+
+    @cached_property
+    def hooks(self):
+        for hook in self.repo_config['hooks']:
+            if hook['id'] not in self.meta_hooks:
+                logger.error(
+                    '`{}` is not a valid meta hook.  '
+                    'Typo? Perhaps it is introduced in a newer version?  '
+                    'Often `pre-commit autoupdate` fixes this.'.format(
+                        hook['id'],
+                    ),
+                )
+                exit(1)
+
+        return tuple(
+            (
+                hook['id'],
+                apply_defaults(
+                    validate(
+                        dict(self.meta_hooks[hook['id']], **hook),
+                        MANIFEST_HOOK_DICT,
+                    ),
+                    MANIFEST_HOOK_DICT,
+                ),
+            )
+            for hook in self.repo_config['hooks']
+        )
+
+
 class _UniqueList(list):
     def __init__(self):
         self._set = set()

pre_commit/schema.py

@@ -101,6 +101,9 @@ def _check_conditional(self, dct):
         if isinstance(self.condition_value, Not):
             op = 'is'
             cond_val = self.condition_value.val
+        elif isinstance(self.condition_value, NotIn):
+            op = 'is any of'
+            cond_val = self.condition_value.values
         else:
             op = 'is not'
             cond_val = self.condition_value
@@ -206,6 +209,14 @@ class Not(object):
         return other is not MISSING and other != self.val
 
 
+class NotIn(object):
+    def __init__(self, values):
+        self.values = values
+
+    def __eq__(self, other):
+        return other is not MISSING and other not in self.values
+
+
 def check_any(_):
     pass