blackd.py

   1 import asyncio
   2 from concurrent.futures import Executor, ProcessPoolExecutor
   3 from functools import partial
   4 import logging
   5
   6 from aiohttp import web
   7 import black
   8 import click
   9
  10 # This is used internally by tests to shut down the server prematurely
  11 _stop_signal = asyncio.Event()
  12
  13 VERSION_HEADER = "X-Protocol-Version"
  14 LINE_LENGTH_HEADER = "X-Line-Length"
  15 PYTHON_VARIANT_HEADER = "X-Python-Variant"
  16 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
  17 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
  18
  19
  20 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  21 @click.option(
  22     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  23 )
  24 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  25 @click.version_option(version=black.__version__)
  26 def main(bind_host: str, bind_port: int) -> None:
  27     logging.basicConfig(level=logging.INFO)
  28     app = make_app()
  29     ver = black.__version__
  30     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  31     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  32
  33
  34 def make_app() -> web.Application:
  35     app = web.Application()
  36     executor = ProcessPoolExecutor()
  37     app.add_routes([web.post("/", partial(handle, executor=executor))])
  38     return app
  39
  40
  41 async def handle(request: web.Request, executor: Executor) -> web.Response:
  42     try:
  43         if request.headers.get(VERSION_HEADER, "1") != "1":
  44             return web.Response(
  45                 status=501, text="This server only supports protocol version 1"
  46             )
  47         try:
  48             line_length = int(
  49                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  50             )
  51         except ValueError:
  52             return web.Response(status=400, text="Invalid line length header value")
  53         py36 = False
  54         pyi = False
  55         if PYTHON_VARIANT_HEADER in request.headers:
  56             value = request.headers[PYTHON_VARIANT_HEADER]
  57             if value == "pyi":
  58                 pyi = True
  59             else:
  60                 try:
  61                     major, *rest = value.split(".")
  62                     if int(major) == 3 and len(rest) > 0:
  63                         if int(rest[0]) >= 6:
  64                             py36 = True
  65                 except ValueError:
  66                     return web.Response(
  67                         status=400, text=f"Invalid value for {PYTHON_VARIANT_HEADER}"
  68                     )
  69         skip_string_normalization = bool(
  70             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
  71         )
  72         fast = False
  73         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
  74             fast = True
  75         mode = black.FileMode.from_configuration(
  76             py36=py36, pyi=pyi, skip_string_normalization=skip_string_normalization
  77         )
  78         req_bytes = await request.content.read()
  79         charset = request.charset if request.charset is not None else "utf8"
  80         req_str = req_bytes.decode(charset)
  81         loop = asyncio.get_event_loop()
  82         formatted_str = await loop.run_in_executor(
  83             executor,
  84             partial(
  85                 black.format_file_contents,
  86                 req_str,
  87                 line_length=line_length,
  88                 fast=fast,
  89                 mode=mode,
  90             ),
  91         )
  92         return web.Response(
  93             content_type=request.content_type, charset=charset, text=formatted_str
  94         )
  95     except black.NothingChanged:
  96         return web.Response(status=204)
  97     except black.InvalidInput as e:
  98         return web.Response(status=400, text=str(e))
  99     except Exception as e:
 100         logging.exception("Exception during handling a request")
 101         return web.Response(status=500, text=str(e))
 102
 103
 104 if __name__ == "__main__":
 105     black.patch_click()
 106     main()