Add first version of patchinator

patchinator.py

@@ -0,0 +1,195 @@
+#!/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
+
+
+### 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):
+        self.match = match
+        self.sub = sub
+
+    def __call__(self, value):
+        return re.sub(self.match, self.sub, value)
+
+
+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():]            
+
+
+### 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 DestPatch(object):
+    """
+    Patches a destination file in place with transforms
+    """
+
+    def __init__(self, dest_path, transforms):
+        self.dest_path = dest_path
+        self.transforms = transforms
+
+    def run(self, source_dir, dest_dir):
+        print("PATCH: %s" % (self.dest_path, ))
+        # Open and read in the file
+        dest = os.path.join(dest_dir, self.dest_path)
+        with open(dest, "r") as fh:
+            content = fh.read()
+        # Run transforms
+        for transform in self.transforms:
+            content = transform(content)
+        # Save new file
+        with open(dest, "w") as fh:
+            fh.write(content)
+
+
+### Main class ###
+
+
+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")
+]
+
+
+class Patchinator(object):
+
+    operations = [
+        FileMap(
+            "channels/__init__.py", "django/channels/__init__.py", global_transforms,
+        ),
+        FileMap(
+            "channels/asgi.py", "django/channels/asgi.py", global_transforms,
+        ),
+        FileMap(
+            "channels/auth.py", "django/channels/auth.py", global_transforms,
+        ),
+        FileMap(
+            "channels/channel.py", "django/channels/channel.py", global_transforms,
+        ),
+        FileMap(
+            "channels/database_layer.py", "django/channels/database_layer.py", global_transforms,
+        ),
+        FileMap(
+            "channels/exceptions.py", "django/channels/exceptions.py", global_transforms,
+        ),
+        FileMap(
+            "channels/handler.py", "django/core/handlers/asgi.py", global_transforms,
+        ),
+        FileMap(
+            "channels/routing.py", "django/channels/routing.py", global_transforms,
+        ),
+        FileMap(
+            "channels/sessions.py", "django/channels/sessions.py", global_transforms,
+        ),
+        FileMap(
+            "channels/staticfiles.py", "django/channels/staticfiles.py", global_transforms,
+        ),
+        FileMap(
+            "channels/utils.py", "django/channels/utils.py", global_transforms,
+        ),
+        FileMap(
+            "channels/worker.py", "django/channels/worker.py", global_transforms,
+        ),
+        FileMap(
+            "channels/management/commands/runworker.py", "django/core/management/commands/runworker.py", global_transforms,
+        ),
+        FileMap(
+            "channels/tests/base.py", "django/test/channels.py", global_transforms,
+        ),
+        FileMap(
+            "channels/tests/test_database_layer.py", "tests/channels_tests/test_database_layer.py", global_transforms,
+        ),
+        FileMap(
+            "channels/tests/test_handler.py", "tests/channels_tests/test_handler.py", global_transforms,
+        ),
+        FileMap(
+            "channels/tests/test_routing.py", "tests/channels_tests/test_routing.py", global_transforms,
+        ),
+        FileMap(
+            "channels/tests/test_request.py", "tests/channels_tests/test_request.py", global_transforms,
+        ),
+        DestPatch(
+            "django/test/__init__.py", [
+                Insert(r"from django.test.utils import", "from django.test.channels import ChannelTestCase\n"),
+                Insert(r"'LiveServerTestCase'", ", 'ChannelTestCase'", after=True),
+            ]
+        )
+    ]
+
+    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")