Repository: pre-commit/pre-commit (python)

Issue:
Expose `negate` and deprecate pcre hooks
See https://github.com/pre-commit/pre-commit/blob/b05cc4077e621cec637b22d6ad2b80ee84749f97/pre_commit/xargs.py#L48

I imagine something like this:

``` yaml
- id: test
  language: system
  negate_returncode: true
  entry: grep -P herp
```

Instead of the equivalent pcre hook


Pull request description:
Implement pygrep language as a replacement for pcre
This is more cross-platform compatible than pcre.

Resolves #404

Patch:
diff --git a/pre_commit/languages/all.py b/pre_commit/languages/all.py
index 67b7dde..514ba61 100644
--- a/pre_commit/languages/all.py
+++ b/pre_commit/languages/all.py
@@ -5,6 +5,7 @@ from pre_commit.languages import docker_image
 from pre_commit.languages import golang
 from pre_commit.languages import node
 from pre_commit.languages import pcre
+from pre_commit.languages import pygrep
 from pre_commit.languages import python
 from pre_commit.languages import ruby
 from pre_commit.languages import script
@@ -54,6 +55,7 @@ languages = {
     'golang': golang,
     'node': node,
     'pcre': pcre,
+    'pygrep': pygrep,
     'python': python,
     'ruby': ruby,
     'script': script,
diff --git a/pre_commit/languages/pygrep.py b/pre_commit/languages/pygrep.py
new file mode 100644
index 0000000..4914fd6
--- /dev/null
+++ b/pre_commit/languages/pygrep.py
@@ -0,0 +1,59 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import argparse
+import re
+import sys
+
+from pre_commit import output
+from pre_commit.languages import helpers
+from pre_commit.xargs import xargs
+
+
+ENVIRONMENT_DIR = None
+get_default_version = helpers.basic_get_default_version
+healthy = helpers.basic_healthy
+install_environment = helpers.no_install
+
+
+def _process_filename_by_line(pattern, filename):
+    retv = 0
+    with open(filename, 'rb') as f:
+        for line_no, line in enumerate(f, start=1):
+            if pattern.search(line):
+                retv = 1
+                output.write('{}:{}:'.format(filename, line_no))
+                output.write_line(line.rstrip(b'\r\n'))
+    return retv
+
+
+def run_hook(repo_cmd_runner, hook, file_args):
+    exe = (sys.executable, '-m', __name__)
+    exe += tuple(hook['args']) + (hook['entry'],)
+    return xargs(exe, file_args)
+
+
+def main(argv=None):
+    parser = argparse.ArgumentParser(
+        description=(
+            'grep-like finder using python regexes.  Unlike grep, this tool '
+            'returns nonzero when it finds a match and zero otherwise.  The '
+            'idea here being that matches are "problems".'
+        ),
+    )
+    parser.add_argument('-i', '--ignore-case', action='store_true')
+    parser.add_argument('pattern', help='python regex pattern.')
+    parser.add_argument('filenames', nargs='*')
+    args = parser.parse_args(argv)
+
+    flags = re.IGNORECASE if args.ignore_case else 0
+    pattern = re.compile(args.pattern.encode(), flags)
+
+    retv = 0
+    for filename in args.filenames:
+        retv |= _process_filename_by_line(pattern, filename)
+    return retv
+
+
+if __name__ == '__main__':
+    exit(main())
diff --git a/pre_commit/repository.py b/pre_commit/repository.py
index 675c471..6955a73 100644
--- a/pre_commit/repository.py
+++ b/pre_commit/repository.py
@@ -202,8 +202,8 @@ class LocalRepository(Repository):
     def _cmd_runner_from_deps(self, language_name, deps):
         """local repositories have a cmd runner per hook"""
         language = languages[language_name]
-        # pcre / script / system / docker_image do not have environments so
-        # they work out of the current directory
+        # pcre / pygrep / script / system / docker_image do not have
+        # environments so they work out of the current directory
         if language.ENVIRONMENT_DIR is None:
             return PrefixedCommandRunner(git.get_root())
         else:


Test patch:
diff --git a/testing/fixtures.py b/testing/fixtures.py
index befc3f5..388b344 100644
--- a/testing/fixtures.py
+++ b/testing/fixtures.py
@@ -73,7 +73,7 @@ def config_with_local_hooks():
                 ('id', 'do_not_commit'),
                 ('name', 'Block if "DO NOT COMMIT" is found'),
                 ('entry', 'DO NOT COMMIT'),
-                ('language', 'pcre'),
+                ('language', 'pygrep'),
                 ('files', '^(.*)$'),
             ))],
         ),
diff --git a/testing/resources/pcre_hooks_repo/.pre-commit-hooks.yaml b/testing/resources/pcre_hooks_repo/.pre-commit-hooks.yaml
deleted file mode 100644
index 709d8df..0000000
--- a/testing/resources/pcre_hooks_repo/.pre-commit-hooks.yaml
+++ /dev/null
@@ -1,16 +0,0 @@
--   id: regex-with-quotes
-    name: Regex with quotes
-    entry: "foo'bar"
-    language: pcre
-    files: ''
--   id: other-regex
-    name: Other regex
-    entry: ^\[INFO\]
-    language: pcre
-    files: ''
--   id: regex-with-grep-args
-    name: Regex with grep extra arguments
-    entry: foo.+bar
-    language: pcre
-    files: ''
-    args: [-i]
diff --git a/tests/languages/pygrep_test.py b/tests/languages/pygrep_test.py
new file mode 100644
index 0000000..048a590
--- /dev/null
+++ b/tests/languages/pygrep_test.py
@@ -0,0 +1,40 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import pytest
+
+from pre_commit.languages import pygrep
+
+
+@pytest.fixture
+def some_files(tmpdir):
+    tmpdir.join('f1').write_binary(b'foo\nbar\n')
+    tmpdir.join('f2').write_binary(b'[INFO] hi\n')
+    tmpdir.join('f3').write_binary(b"with'quotes\n")
+    with tmpdir.as_cwd():
+        yield
+
+
+@pytest.mark.usefixtures('some_files')
+@pytest.mark.parametrize(
+    ('pattern', 'expected_retcode', 'expected_out'),
+    (
+        ('baz', 0, ''),
+        ('foo', 1, 'f1:1:foo\n'),
+        ('bar', 1, 'f1:2:bar\n'),
+        (r'(?i)\[info\]', 1, 'f2:1:[INFO] hi\n'),
+        ("h'q", 1, "f3:1:with'quotes\n"),
+    ),
+)
+def test_main(some_files, cap_out, pattern, expected_retcode, expected_out):
+    ret = pygrep.main((pattern, 'f1', 'f2', 'f3'))
+    out = cap_out.get()
+    assert ret == expected_retcode
+    assert out == expected_out
+
+
+def test_ignore_case(some_files, cap_out):
+    ret = pygrep.main(('--ignore-case', 'info', 'f1', 'f2', 'f3'))
+    out = cap_out.get()
+    assert ret == 1
+    assert out == 'f2:1:[INFO] hi\n'
diff --git a/tests/repository_test.py b/tests/repository_test.py
index 8ff9db4..37a609b 100644
--- a/tests/repository_test.py
+++ b/tests/repository_test.py
@@ -1,6 +1,7 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+import collections
 import io
 import os.path
 import re
@@ -36,6 +37,10 @@ from testing.util import xfailif_windows_no_node
 from testing.util import xfailif_windows_no_ruby
 
 
+def _norm_out(b):
+    return b.replace(b'\r\n', b'\n')
+
+
 def _test_hook_repo(
         tempdir_factory,
         store,
@@ -54,7 +59,7 @@ def _test_hook_repo(
     ]
     ret = repo.run_hook(hook_dict, args)
     assert ret[0] == expected_return_code
-    assert ret[1].replace(b'\r\n', b'\n') == expected
+    assert _norm_out(ret[1]) == expected
 
 
 @pytest.mark.integration
@@ -114,7 +119,7 @@ def test_switch_language_versions_doesnt_clobber(tempdir_factory, store):
         ]
         ret = repo.run_hook(hook_dict, [])
         assert ret[0] == 0
-        assert ret[1].replace(b'\r\n', b'\n') == expected_output
+        assert _norm_out(ret[1]) == expected_output
 
     run_on_version('python3.4', b'3.4\n[]\nHello World\n')
     run_on_version('python3.5', b'3.5\n[]\nHello World\n')
@@ -277,25 +282,6 @@ def test_missing_executable(tempdir_factory, store):
     )
 
 
-@pytest.mark.integration
-def test_missing_pcre_support(tempdir_factory, store):
-    orig_find_executable = parse_shebang.find_executable
-
-    def no_grep(exe, **kwargs):
-        if exe == pcre.GREP:
-            return None
-        else:
-            return orig_find_executable(exe, **kwargs)
-
-    with mock.patch.object(parse_shebang, 'find_executable', no_grep):
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'regex-with-quotes', ['/dev/null'],
-            'Executable `{}` not found'.format(pcre.GREP).encode('UTF-8'),
-            expected_return_code=1,
-        )
-
-
 @pytest.mark.integration
 def test_run_a_script_hook(tempdir_factory, store):
     _test_hook_repo(
@@ -330,85 +316,88 @@ def test_run_hook_with_curly_braced_arguments(tempdir_factory, store):
     )
 
 
-@xfailif_no_pcre_support
-@pytest.mark.integration
-def test_pcre_hook_no_match(tempdir_factory, store):
-    path = git_dir(tempdir_factory)
-    with cwd(path):
-        with io.open('herp', 'w') as herp:
-            herp.write('foo')
-
-        with io.open('derp', 'w') as derp:
-            derp.write('bar')
-
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'regex-with-quotes', ['herp', 'derp'], b'',
-        )
-
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'other-regex', ['herp', 'derp'], b'',
-        )
-
+def _make_grep_repo(language, entry, store, args=()):
+    config = collections.OrderedDict((
+        ('repo', 'local'),
+        (
+            'hooks', [
+                collections.OrderedDict((
+                    ('id', 'grep-hook'),
+                    ('name', 'grep-hook'),
+                    ('language', language),
+                    ('entry', entry),
+                    ('args', args),
+                    ('types', ['text']),
+                )),
+            ],
+        ),
+    ))
+    repo = Repository.create(config, store)
+    (_, hook), = repo.hooks
+    return repo, hook
 
-@xfailif_no_pcre_support
-@pytest.mark.integration
-def test_pcre_hook_matching(tempdir_factory, store):
-    path = git_dir(tempdir_factory)
-    with cwd(path):
-        with io.open('herp', 'w') as herp:
-            herp.write("\nherpfoo'bard\n")
 
-        with io.open('derp', 'w') as derp:
-            derp.write('[INFO] information yo\n')
+@pytest.fixture
+def greppable_files(tmpdir):
+    with tmpdir.as_cwd():
+        cmd_output('git', 'init', '.')
+        tmpdir.join('f1').write_binary(b"hello'hi\nworld\n")
+        tmpdir.join('f2').write_binary(b'foo\nbar\nbaz\n')
+        tmpdir.join('f3').write_binary(b'[WARN] hi\n')
+        yield tmpdir
 
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'regex-with-quotes', ['herp', 'derp'], b"herp:2:herpfoo'bard\n",
-            expected_return_code=1,
-        )
 
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'other-regex', ['herp', 'derp'], b'derp:1:[INFO] information yo\n',
-            expected_return_code=1,
-        )
+class TestPygrep(object):
+    language = 'pygrep'
 
+    def test_grep_hook_matching(self, greppable_files, store):
+        repo, hook = _make_grep_repo(self.language, 'ello', store)
+        ret, out, _ = repo.run_hook(hook, ('f1', 'f2', 'f3'))
+        assert ret == 1
+        assert _norm_out(out) == b"f1:1:hello'hi\n"
 
-@xfailif_no_pcre_support
-@pytest.mark.integration
-def test_pcre_hook_case_insensitive_option(tempdir_factory, store):
-    path = git_dir(tempdir_factory)
-    with cwd(path):
-        with io.open('herp', 'w') as herp:
-            herp.write('FoOoOoObar\n')
+    def test_grep_hook_case_insensitive(self, greppable_files, store):
+        repo, hook = _make_grep_repo(self.language, 'ELLO', store, args=['-i'])
+        ret, out, _ = repo.run_hook(hook, ('f1', 'f2', 'f3'))
+        assert ret == 1
+        assert _norm_out(out) == b"f1:1:hello'hi\n"
 
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'regex-with-grep-args', ['herp'], b'herp:1:FoOoOoObar\n',
-            expected_return_code=1,
-        )
+    @pytest.mark.parametrize('regex', ('nope', "foo'bar", r'^\[INFO\]'))
+    def test_grep_hook_not_matching(self, regex, greppable_files, store):
+        repo, hook = _make_grep_repo(self.language, regex, store)
+        ret, out, _ = repo.run_hook(hook, ('f1', 'f2', 'f3'))
+        assert (ret, out) == (0, b'')
 
 
 @xfailif_no_pcre_support
-@pytest.mark.integration
-def test_pcre_many_files(tempdir_factory, store):
-    # This is intended to simulate lots of passing files and one failing file
-    # to make sure it still fails.  This is not the case when naively using
-    # a system hook with `grep -H -n '...'` and expected_return_code=1.
-    path = git_dir(tempdir_factory)
-    with cwd(path):
-        with io.open('herp', 'w') as herp:
-            herp.write('[INFO] info\n')
-
-        _test_hook_repo(
-            tempdir_factory, store, 'pcre_hooks_repo',
-            'other-regex',
-            ['/dev/null'] * 15000 + ['herp'],
-            b'herp:1:[INFO] info\n',
-            expected_return_code=1,
-        )
+class TestPCRE(TestPygrep):
+    """organized as a class for xfailing pcre"""
+    language = 'pcre'
+
+    def test_pcre_hook_many_files(self, greppable_files, store):
+        # This is intended to simulate lots of passing files and one failing
+        # file to make sure it still fails.  This is not the case when naively
+        # using a system hook with `grep -H -n '...'`
+        repo, hook = _make_grep_repo('pcre', 'ello', store)
+        ret, out, _ = repo.run_hook(hook, (os.devnull,) * 15000 + ('f1',))
+        assert ret == 1
+        assert _norm_out(out) == b"f1:1:hello'hi\n"
+
+    def test_missing_pcre_support(self, greppable_files, store):
+        orig_find_executable = parse_shebang.find_executable
+
+        def no_grep(exe, **kwargs):
+            if exe == pcre.GREP:
+                return None
+            else:
+                return orig_find_executable(exe, **kwargs)
+
+        with mock.patch.object(parse_shebang, 'find_executable', no_grep):
+            repo, hook = _make_grep_repo('pcre', 'ello', store)
+            ret, out, _ = repo.run_hook(hook, ('f1', 'f2', 'f3'))
+            assert ret == 1
+            expected = 'Executable `{}` not found'.format(pcre.GREP).encode()
+            assert out == expected
 
 
 def _norm_pwd(path):
@@ -703,7 +692,7 @@ def test_local_python_repo(store):
     (_, hook), = repo.hooks
     ret = repo.run_hook(hook, ('filename',))
     assert ret[0] == 0
-    assert ret[1].replace(b'\r\n', b'\n') == b"['filename']\nHello World\n"
+    assert _norm_out(ret[1]) == b"['filename']\nHello World\n"
 
 
 def test_hook_id_not_present(tempdir_factory, store, fake_log_handler):
diff --git a/tests/runner_test.py b/tests/runner_test.py
index cfca44f..b5c0ce7 100644
--- a/tests/runner_test.py
+++ b/tests/runner_test.py
@@ -70,7 +70,7 @@ def test_local_hooks(tempdir_factory, mock_out_store_directory):
                     ('id', 'do_not_commit'),
                     ('name', 'Block if "DO NOT COMMIT" is found'),
                     ('entry', 'DO NOT COMMIT'),
-                    ('language', 'pcre'),
+                    ('language', 'pygrep'),
                     ('files', '^(.*)$'),
                 )),
             ),
@@ -105,7 +105,7 @@ def test_local_hooks_alt_config(tempdir_factory, mock_out_store_directory):
                     ('id', 'do_not_commit'),
                     ('name', 'Block if "DO NOT COMMIT" is found'),
                     ('entry', 'DO NOT COMMIT'),
-                    ('language', 'pcre'),
+                    ('language', 'pygrep'),
                     ('files', '^(.*)$'),
                 )),
             ),