patchinator.py

#!/usr/bin/python
"""
Script that automatically generates a Django patch from the Channels codebase
based on some simple rules and string replacements.

Once Channels lands in Django, will be reversed to instead generate this
third-party app from the now-canonical Django source.
"""

import re
import os.path
import sys

from isort import SortImports


# Transforms: Turn one content string into another

class Replacement(object):
    """
    Represents a string replacement in a file; uses a regular expression to
    substitute strings in the file.
    """

    def __init__(self, match, sub, regex=True):
        self.match = match
        self.sub = sub
        self.regex = regex

    def __call__(self, value):
        if self.regex:
            return re.sub(self.match, self.sub, value)
        else:
            return value.replace(self.match, self.sub)


class Insert(object):
    """
    Inserts a string before/after another in a file, one time only, with multiline match.
    """

    def __init__(self, match, to_insert, after=False):
        self.match = match
        self.to_insert = to_insert
        self.after = after

    def __call__(self, value):
        match = re.search(self.match, value, flags=re.MULTILINE)
        if not match:
            raise ValueError("Could not find match %s" % self.match)
        if self.after:
            return value[:match.end()] + self.to_insert + value[match.end():]
        else:
            return value[:match.start()] + self.to_insert + value[match.start():]


class Isort(object):
    """
    Runs isort on the file
    """

    def __call__(self, value):
        return SortImports(file_contents=value).output


# Operations: Copy or patch files

class FileMap(object):
    """
    Represents a file map from the source to the destination, with
    optional extra regex transforms.
    """

    def __init__(self, source_path, dest_path, transforms, makedirs=True):
        self.source_path = source_path
        self.dest_path = dest_path
        self.transforms = transforms
        self.makedirs = makedirs

    def run(self, source_dir, dest_dir):
        print("COPY: %s -> %s" % (self.source_path, self.dest_path))
        # Open and read in source file
        source = os.path.join(source_dir, self.source_path)
        with open(source, "r") as fh:
            content = fh.read()
        # Run transforms
        for transform in self.transforms:
            content = transform(content)
        # Save new file
        dest = os.path.join(dest_dir, self.dest_path)
        if self.makedirs:
            if not os.path.isdir(os.path.dirname(dest)):
                os.makedirs(os.path.dirname(dest))
        with open(dest, "w") as fh:
            fh.write(content)


class NewFile(object):
    """
    Writes a file to the destination, either blank or with some content from
    a string.
    """

    def __init__(self, dest_path, content=""):
        self.dest_path = dest_path
        self.content = content

    def run(self, source_dir, dest_dir):
        print("NEW: %s" % (self.dest_path, ))
        # Save new file
        dest = os.path.join(dest_dir, self.dest_path)
        with open(dest, "w") as fh:
            fh.write(self.content)


# Main class and config


global_transforms = [
    Replacement(r"import channels.([a-zA-Z0-9_\.]+)$", r"import django.channels.\1 as channels"),
    Replacement(r"from channels import", r"from django.channels import"),
    Replacement(r"from channels.([a-zA-Z0-9_\.]+) import", r"from django.channels.\1 import"),
    Replacement(r"from .handler import", r"from django.core.handlers.asgi import"),
    Replacement(r"from django.channels.tests import", r"from django.test.channels import"),
    Replacement(r"from django.channels.handler import", r"from django.core.handlers.asgi import"),
    Replacement(r"channels.tests.test_routing", r"channels_tests.test_routing"),
    Replacement(r"django.core.urlresolvers", r"django.urls"),
]

python_transforms = global_transforms + [
    Isort(),
]

docs_transforms = global_transforms + [
    Replacement(r"<concepts>`", r"</topics/channels/concepts>`"),
    Replacement(r":doc:`concepts`", r":doc:`/topics/channels/concepts`"),
    Replacement(r":doc:`deploying`", r":doc:`/topics/channels/deploying`"),
    Replacement(r":doc:`scaling`", r":doc:`/topics/channels/scaling`"),
    Replacement(r":doc:`getting-started`", r":doc:`/intro/channels`"),
    Replacement(r"<backends>`", r"</ref/channels/backends>`"),
    Replacement(r":doc:`backends`", r":doc:`/ref/channels/backends`"),
    Replacement(r":doc:`([\w\d\s]+) <asgi>`", r"`\1 <http://channels.readthedocs.org/en/latest/asgi.html>`_"),
    Replacement(r"\n\(.*installation>`\)\n", r""),
    Replacement(r":doc:`installed Channels correctly <installation>`", r"added the channel layer setting"),
    Replacement(r"Channels", r"channels"),
    Replacement(r"Started with channels", r"Started with Channels"),
    Replacement(r"Running with channels", r"Running with Channels"),
    Replacement(r"channels consumers", r"channel consumers"),
    Replacement(r"channels' design", r"The channels design"),
    Replacement(r"channels is being released", r"Channels is being released"),
    Replacement(r"channels is", r"channels are"),
    Replacement(r"channels provides a", r"Channels provides a"),
    Replacement(r"channels can use", r"Channels can use"),
    Replacement(r"channels Concepts", r"Channels Concepts"),
    Replacement(r"channels works", r"channels work"),
]


class Patchinator(object):

    operations = [
        FileMap(
            "channels/asgi.py", "django/channels/asgi.py", python_transforms + [
                Replacement("if django.VERSION[1] > 9:\n        django.setup(set_prefix=False)\n    else:\n        django.setup()", "django.setup(set_prefix=False)", regex=False),  # NOQA
            ],
        ),
        FileMap(
            "channels/auth.py", "django/channels/auth.py", python_transforms,
        ),
        FileMap(
            "channels/channel.py", "django/channels/channel.py", python_transforms,
        ),
        FileMap(
            "channels/exceptions.py", "django/channels/exceptions.py", python_transforms,
        ),
        FileMap(
            "channels/handler.py", "django/core/handlers/asgi.py", python_transforms,
        ),
        FileMap(
            "channels/routing.py", "django/channels/routing.py", python_transforms,
        ),
        FileMap(
            "channels/message.py", "django/channels/message.py", python_transforms,
        ),
        FileMap(
            "channels/sessions.py", "django/channels/sessions.py", python_transforms,
        ),
        FileMap(
            "channels/staticfiles.py", "django/contrib/staticfiles/consumers.py", python_transforms,
        ),
        FileMap(
            "channels/utils.py", "django/channels/utils.py", python_transforms,
        ),
        FileMap(
            "channels/worker.py", "django/channels/worker.py", python_transforms,
        ),
        FileMap(
            "channels/management/commands/runworker.py",
            "django/core/management/commands/runworker.py",
            python_transforms,
        ),
        # Tests
        FileMap(
            "channels/tests/base.py", "django/test/channels.py", python_transforms,
        ),
        NewFile(
            "tests/channels_tests/__init__.py",
        ),
        FileMap(
            "channels/tests/test_handler.py", "tests/channels_tests/test_handler.py", python_transforms,
        ),
        FileMap(
            "channels/tests/test_routing.py", "tests/channels_tests/test_routing.py", python_transforms,
        ),
        FileMap(
            "channels/tests/test_request.py", "tests/channels_tests/test_request.py", python_transforms,
        ),
        FileMap(
            "channels/tests/test_sessions.py", "tests/channels_tests/test_sessions.py", python_transforms,
        ),
        # Docs
        FileMap(
            "docs/backends.rst", "docs/ref/channels/backends.txt", docs_transforms,
        ),
        FileMap(
            "docs/concepts.rst", "docs/topics/channels/concepts.txt", docs_transforms,
        ),
        FileMap(
            "docs/deploying.rst", "docs/topics/channels/deploying.txt", docs_transforms,
        ),
        FileMap(
            "docs/getting-started.rst", "docs/intro/channels.txt", docs_transforms,
        ),
        FileMap(
            "docs/reference.rst", "docs/ref/channels/api.txt", docs_transforms,
        ),
        FileMap(
            "docs/testing.rst", "docs/topics/channels/testing.txt", docs_transforms,
        ),
        FileMap(
            "docs/cross-compat.rst", "docs/topics/channels/cross-compat.txt", docs_transforms,
        ),
    ]

    def __init__(self, source, destination):
        self.source = os.path.abspath(source)
        self.destination = os.path.abspath(destination)

    def run(self):
        print("Patchinator running.\n Source: %s\n Destination: %s" % (self.source, self.destination))
        for operation in self.operations:
            operation.run(self.source, self.destination)


if __name__ == '__main__':
    try:
        Patchinator(os.path.dirname(__file__), sys.argv[1]).run()
    except IndexError:
        print("Supply the target Django directory on the command line")