Add first class support for golang hooks

pre_commit/languages/all.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 from pre_commit.languages import docker
+from pre_commit.languages import golang
 from pre_commit.languages import node
 from pre_commit.languages import pcre
 from pre_commit.languages import python
@@ -43,6 +44,7 @@ from pre_commit.languages import system
 
 languages = {
     'docker': docker,
+    'golang': golang,
     'node': node,
     'pcre': pcre,
     'python': python,

pre_commit/languages/docker.py

@@ -60,9 +60,8 @@ def install_environment(
     assert repo_cmd_runner.exists('Dockerfile'), (
         'No Dockerfile was found in the hook repository'
     )
-    assert version == 'default', (
-        'Pre-commit does not support language_version for docker '
-    )
+    helpers.assert_version_default('docker', version)
+    helpers.assert_no_additional_deps('docker', additional_dependencies)
     assert_docker_available()
 
     directory = repo_cmd_runner.path(

pre_commit/languages/golang.py

@@ -0,0 +1,72 @@
+from __future__ import unicode_literals
+
+import contextlib
+import os.path
+
+from pre_commit import git
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import Var
+from pre_commit.languages import helpers
+from pre_commit.util import clean_path_on_failure
+from pre_commit.util import cmd_output
+from pre_commit.xargs import xargs
+
+
+ENVIRONMENT_DIR = 'golangenv'
+
+
+def get_env_patch(venv):  # pragma: windows no cover
+    return (
+        ('PATH', (os.path.join(venv, 'bin'), os.pathsep, Var('PATH'))),
+    )
+
+
+@contextlib.contextmanager
+def in_env(repo_cmd_runner):  # pragma: windows no cover
+    envdir = repo_cmd_runner.path(
+        helpers.environment_dir(ENVIRONMENT_DIR, 'default'),
+    )
+    with envcontext(get_env_patch(envdir)):
+        yield
+
+
+def guess_go_dir(remote_url):
+    if remote_url.endswith('.git'):
+        remote_url = remote_url[:-1 * len('.git')]
+    remote_url = remote_url.replace(':', '/')
+    looks_like_url = '//' in remote_url or '@' in remote_url
+    if looks_like_url:
+        _, _, remote_url = remote_url.rpartition('//')
+        _, _, remote_url = remote_url.rpartition('@')
+        return remote_url
+    else:
+        return 'unknown_src_dir'
+
+
+def install_environment(
+        repo_cmd_runner,
+        version='default',
+        additional_dependencies=(),
+):  # pragma: windows no cover
+    helpers.assert_version_default('golang', version)
+    helpers.assert_no_additional_deps('golang', additional_dependencies)
+    directory = repo_cmd_runner.path(
+        helpers.environment_dir(ENVIRONMENT_DIR, 'default'),
+    )
+
+    with clean_path_on_failure(directory):
+        remote = git.get_remote_url(repo_cmd_runner.path())
+        repo_src_dir = os.path.join(directory, 'src', guess_go_dir(remote))
+
+        # Clone into the goenv we'll create
+        helpers.run_setup_cmd(
+            repo_cmd_runner, ('git', 'clone', '.', repo_src_dir),
+        )
+
+        env = dict(os.environ, GOPATH=directory)
+        cmd_output('go', 'get', './...', cwd=repo_src_dir, env=env)
+
+
+def run_hook(repo_cmd_runner, hook, file_args):  # pragma: windows no cover
+    with in_env(repo_cmd_runner):
+        return xargs(helpers.to_cmd(hook), file_args)

pre_commit/languages/helpers.py

@@ -18,3 +18,18 @@ def environment_dir(ENVIRONMENT_DIR, language_version):
 
 def to_cmd(hook):
     return tuple(shlex.split(hook['entry'])) + tuple(hook['args'])
+
+
+def assert_version_default(binary, version):
+    if version != 'default':
+        raise AssertionError(
+            'For now, pre-commit requires system-installed {}'.format(binary),
+        )
+
+
+def assert_no_additional_deps(lang, additional_deps):
+    if additional_deps:
+        raise AssertionError(
+            'For now, pre-commit does not support '
+            'additional_dependencies for {}'.format(lang),
+        )

pre_commit/languages/swift.py

@@ -33,9 +33,8 @@ def install_environment(
         version='default',
         additional_dependencies=(),
 ):  # pragma: windows no cover
-    assert version == 'default', (
-        'Pre-commit does not support language_version for docker '
-    )
+    helpers.assert_version_default('swift', version)
+    helpers.assert_no_additional_deps('swift', additional_dependencies)
     directory = repo_cmd_runner.path(
         helpers.environment_dir(ENVIRONMENT_DIR, 'default'),
     )