Add flake8 plugin for Breezy.

setup.py

@@ -127,6 +127,9 @@ setuptools.setup(
             'quiet-filename = flake8.formatting.default:FilenameOnly',
             'quiet-nothing = flake8.formatting.default:Nothing',
         ],
+        'breezy.plugin': [
+            'flake8 = flake8.main.breezy',
+        ],
     },
     classifiers=[
         "Development Status :: 5 - Production/Stable",

src/flake8/main/breezy.py

@@ -0,0 +1,145 @@
+"""Module containing the Breezy hook interface and helpers.
+
+.. autofunction:: install
+
+"""
+
+
+from __future__ import absolute_import
+
+
+__all__ = ("install")
+
+
+import os
+
+
+def install():
+    """Install the Breezy hook script.
+
+    This searches for the ``.bzr`` directory and will install an executable
+    pre-commit python script in the hooks sub-directory if one does not
+    already exist.
+
+    It will also print a message to stdout about how to configure the hook.
+
+    :returns:
+        True if successful, False if the Breezy directory doesn't exist.
+    :rtype:
+        bool
+    """
+    import breezy.bzr  # noqa: F401
+    from breezy.branch import Branch
+    from breezy.errors import NotBranchError
+
+    try:
+        branch, _ = Branch.open_containing('.')
+    except NotBranchError:
+        return False
+
+    config = branch.get_config_stack()
+    config.set('flake8.pre_commit_check', True)
+
+    print("Breezy pre-commit hook installed, for configuration options see")
+    print("http://flake8.pycqa.org/en/latest/user/using-hooks.html")
+    return True
+
+
+def _delta_files(tree_delta):
+    for path, file_id, kind in tree_delta.added:
+        if kind == 'file':
+            yield path
+    for (path, file_id, kind, text_modified,
+            meta_modified) in tree_delta.modified:
+        if kind == 'file' and text_modified:
+            yield path
+    for (oldpath, newpath, id, kind, text_modified,
+            meta_modified) in tree_delta.renamed:
+        if kind == 'file' and text_modified:
+            yield newpath
+    for path, id, old_kind, new_kind in tree_delta.kind_changed:
+        if new_kind == 'file':
+            yield path
+
+
+def _copy_files_to(tree, target_dir, files):
+    from breezy import osutils
+    for relpath in files:
+        target_path = os.path.join(target_dir, relpath)
+        os.makedirs(os.path.dirname(target_path))
+        with tree.get_file(relpath) as inf, \
+                open(target_path, 'wb') as outf:
+            osutils.pumpfile(inf, outf)
+            yield target_path
+
+
+def _update_paths(checker_manager, temp_prefix):
+    temp_prefix_length = len(temp_prefix)
+    for checker in checker_manager.checkers:
+        filename = checker.display_name
+        if filename.startswith(temp_prefix):
+            checker.display_name = os.path.relpath(
+                filename[temp_prefix_length:])
+
+
+def hook(config, tree_delta, future_tree):
+    """Execute Flake8 on the files in git's index.
+
+    Determine which files are about to be committed and run Flake8 over
+    them to check for violations.
+
+    :param bool strict:
+        If True, return the total number of errors/violations found by
+        Flake8. This will cause the hook to fail.
+    :returns:
+        Total number of errors found during the run.
+    :rtype:
+        int
+    """
+    from flake8.main import application
+    import tempfile
+
+    strict = config.get('flake8.strict')
+
+    app = application.Application()
+    with tempfile.TemporaryDirectory() as tempdir:
+        filepaths = list(_copy_files_to(
+            future_tree, tempdir, _delta_files(tree_delta)))
+        app.initialize([tempdir])
+        app.options._running_from_vcs = True
+        app.run_checks(filepaths)
+        _update_paths(app.file_checker_manager, tempdir)
+        app.report_errors()
+
+    from breezy.errors import BzrError
+
+    class Flake8Errors(BzrError):
+
+        _fmt = ("Running in strict flake8 mode; aborting commit, "
+                "since %(errors)d flake8 errors exist.")
+
+        def __init__(self, errors):
+            self.errors = errors
+
+    if strict:
+        if app.result_count:
+            raise Flake8Errors(app.result_count)
+
+
+def _check_flake8(local, master, old_revno, old_revid, future_revno,
+                  future_revid, tree_delta, future_tree):
+    branch = local or master
+    config = branch.get_config_stack()
+    if config.get('flake8.pre_commit_check'):
+        hook(config, tree_delta, future_tree)
+
+
+if __name__ == 'breezy.plugins.flake8':
+    __doc__ = """Flake8 type checking before commits.
+
+Set the ``flake8.pre_commit_check`` configuration variable to True
+to enable this.
+"""
+    from breezy.branch import Branch
+    Branch.hooks.install_named_hook(
+        'pre_commit', _check_flake8, 'Check flake8')

src/flake8/main/vcs.py

@@ -1,5 +1,6 @@
 """Module containing some of the logic for our VCS installation logic."""
 from flake8 import exceptions as exc
+from flake8.main import breezy
 from flake8.main import git
 from flake8.main import mercurial
 
@@ -8,7 +9,9 @@ from flake8.main import mercurial
 # as plugins, e.g., adding a flake8.vcs entry-point. In that case, this
 # dictionary should disappear, and this module might contain more code for
 # managing those bits (in conjuntion with flake8.plugins.manager).
-_INSTALLERS = {"git": git.install, "mercurial": mercurial.install}
+_INSTALLERS = {"git": git.install,
+               "mercurial": mercurial.install,
+               "breezy": breezy.install}
 
 
 def install(option, option_string, value, parser):