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 SKIP_NUMERIC_UNDERSCORE_NORMALIZATION_HEADER = "X-Skip-Numeric-Underscore-Normalization"
  18 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
  19
  20
  21 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  22 @click.option(
  23     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  24 )
  25 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  26 @click.version_option(version=black.__version__)
  27 def main(bind_host: str, bind_port: int) -> None:
  28     logging.basicConfig(level=logging.INFO)
  29     app = make_app()
  30     ver = black.__version__
  31     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  32     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  33
  34
  35 def make_app() -> web.Application:
  36     app = web.Application()
  37     executor = ProcessPoolExecutor()
  38     app.add_routes([web.post("/", partial(handle, executor=executor))])
  39     return app
  40
  41
  42 async def handle(request: web.Request, executor: Executor) -> web.Response:
  43     try:
  44         if request.headers.get(VERSION_HEADER, "1") != "1":
  45             return web.Response(
  46                 status=501, text="This server only supports protocol version 1"
  47             )
  48         try:
  49             line_length = int(
  50                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  51             )
  52         except ValueError:
  53             return web.Response(status=400, text="Invalid line length header value")
  54         py36 = False
  55         pyi = False
  56         if PYTHON_VARIANT_HEADER in request.headers:
  57             value = request.headers[PYTHON_VARIANT_HEADER]
  58             if value == "pyi":
  59                 pyi = True
  60             else:
  61                 try:
  62                     major, *rest = value.split(".")
  63                     if int(major) == 3 and len(rest) > 0:
  64                         if int(rest[0]) >= 6:
  65                             py36 = True
  66                 except ValueError:
  67                     return web.Response(
  68                         status=400, text=f"Invalid value for {PYTHON_VARIANT_HEADER}"
  69                     )
  70         skip_string_normalization = bool(
  71             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
  72         )
  73         skip_numeric_underscore_normalization = bool(
  74             request.headers.get(SKIP_NUMERIC_UNDERSCORE_NORMALIZATION_HEADER, False)
  75         )
  76         fast = False
  77         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
  78             fast = True
  79         mode = black.FileMode.from_configuration(
  80             py36=py36,
  81             pyi=pyi,
  82             skip_string_normalization=skip_string_normalization,
  83             skip_numeric_underscore_normalization=skip_numeric_underscore_normalization,
  84         )
  85         req_bytes = await request.content.read()
  86         charset = request.charset if request.charset is not None else "utf8"
  87         req_str = req_bytes.decode(charset)
  88         loop = asyncio.get_event_loop()
  89         formatted_str = await loop.run_in_executor(
  90             executor,
  91             partial(
  92                 black.format_file_contents,
  93                 req_str,
  94                 line_length=line_length,
  95                 fast=fast,
  96                 mode=mode,
  97             ),
  98         )
  99         return web.Response(
 100             content_type=request.content_type, charset=charset, text=formatted_str
 101         )
 102     except black.NothingChanged:
 103         return web.Response(status=204)
 104     except black.InvalidInput as e:
 105         return web.Response(status=400, text=str(e))
 106     except Exception as e:
 107         logging.exception("Exception during handling a request")
 108         return web.Response(status=500, text=str(e))
 109
 110
 111 if __name__ == "__main__":
 112     black.patch_click()
 113     main()