First cut at Perl hook support

pre_commit/languages/all.py

@@ -11,6 +11,7 @@ from pre_commit.languages import docker_image
 from pre_commit.languages import fail
 from pre_commit.languages import golang
 from pre_commit.languages import node
+from pre_commit.languages import perl
 from pre_commit.languages import pygrep
 from pre_commit.languages import python
 from pre_commit.languages import python_venv
@@ -45,6 +46,7 @@ languages = {
     'fail': Language(name='fail', ENVIRONMENT_DIR=fail.ENVIRONMENT_DIR, get_default_version=fail.get_default_version, healthy=fail.healthy, install_environment=fail.install_environment, run_hook=fail.run_hook),  # noqa: E501
     'golang': Language(name='golang', ENVIRONMENT_DIR=golang.ENVIRONMENT_DIR, get_default_version=golang.get_default_version, healthy=golang.healthy, install_environment=golang.install_environment, run_hook=golang.run_hook),  # noqa: E501
     'node': Language(name='node', ENVIRONMENT_DIR=node.ENVIRONMENT_DIR, get_default_version=node.get_default_version, healthy=node.healthy, install_environment=node.install_environment, run_hook=node.run_hook),  # noqa: E501
+    'perl': Language(name='perl', ENVIRONMENT_DIR=perl.ENVIRONMENT_DIR, get_default_version=perl.get_default_version, healthy=perl.healthy, install_environment=perl.install_environment, run_hook=perl.run_hook),  # noqa: E501
     'pygrep': Language(name='pygrep', ENVIRONMENT_DIR=pygrep.ENVIRONMENT_DIR, get_default_version=pygrep.get_default_version, healthy=pygrep.healthy, install_environment=pygrep.install_environment, run_hook=pygrep.run_hook),  # noqa: E501
     'python': Language(name='python', ENVIRONMENT_DIR=python.ENVIRONMENT_DIR, get_default_version=python.get_default_version, healthy=python.healthy, install_environment=python.install_environment, run_hook=python.run_hook),  # noqa: E501
     'python_venv': Language(name='python_venv', ENVIRONMENT_DIR=python_venv.ENVIRONMENT_DIR, get_default_version=python_venv.get_default_version, healthy=python_venv.healthy, install_environment=python_venv.install_environment, run_hook=python_venv.run_hook),  # noqa: E501

pre_commit/languages/perl.py

@@ -0,0 +1,66 @@
+import contextlib
+import os
+from typing import Generator
+from typing import Sequence
+from typing import Tuple
+
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import PatchesT
+from pre_commit.envcontext import Var
+from pre_commit.hook import Hook
+from pre_commit.languages import helpers
+from pre_commit.prefix import Prefix
+from pre_commit.util import clean_path_on_failure
+
+ENVIRONMENT_DIR = 'perl_env'
+get_default_version = helpers.basic_get_default_version
+healthy = helpers.basic_healthy
+
+
+def _envdir(prefix: Prefix, version: str) -> str:
+    directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
+    return prefix.path(directory)
+
+
+def get_env_patch(venv: str) -> PatchesT:
+    return (
+        ('PATH', (os.path.join(venv, 'bin'), os.pathsep, Var('PATH'))),
+        ('PERL5LIB', os.path.join(venv, 'lib', 'perl5')),
+        ('PERL_MB_OPT', f'--install_base {venv}'),
+        (
+            'PERL_MM_OPT', (
+                f'INSTALL_BASE={venv}'
+                ' INSTALLSITEMAN1DIR=none INSTALLSITEMAN3DIR=none'
+            ),
+        ),
+    )
+
+
+@contextlib.contextmanager
+def in_env(
+        prefix: Prefix,
+        language_version: str,
+) -> Generator[None, None, None]:
+    with envcontext(get_env_patch(_envdir(prefix, language_version))):
+        yield
+
+
+def install_environment(
+        prefix: Prefix, version: str, additional_dependencies: Sequence[str],
+) -> None:
+    helpers.assert_version_default('perl', version)
+
+    with clean_path_on_failure(_envdir(prefix, version)):
+        with in_env(prefix, version):
+            helpers.run_setup_cmd(
+                prefix, ('cpan', '-T', '.', *additional_dependencies),
+            )
+
+
+def run_hook(
+        hook: 'Hook',
+        file_args: Sequence[str],
+        color: bool,
+) -> Tuple[int, bytes]:
+    with in_env(hook.prefix, hook.language_version):
+        return helpers.run_xargs(hook, hook.cmd, file_args, color=color)