djavu-asus/emacs/elpa/elpy-20230803.1455/elpy/rpc.py

   1 """A simple JSON-RPC-like server.
   2
   3 The server will read and write lines of JSON-encoded method calls and
   4 responses.
   5
   6 See the documentation of the JSONRPCServer class for further details.
   7
   8 """
   9
  10 import json
  11 import sys
  12 import traceback
  13
  14
  15 class JSONRPCServer(object):
  16     """Simple JSON-RPC-like server.
  17
  18     This class will read single-line JSON expressions from stdin,
  19     decode them, and pass them to a handler. Return values from the
  20     handler will be JSON-encoded and written to stdout.
  21
  22     To implement a handler, you need to subclass this class and add
  23     methods starting with "rpc_". Methods then will be found.
  24
  25     Method calls should be encoded like this:
  26
  27     {"id": 23, "method": "method_name", "params": ["foo", "bar"]}
  28
  29     This will call self.rpc_method("foo", "bar").
  30
  31     Responses will be encoded like this:
  32
  33     {"id": 23, "result": "foo"}
  34
  35     Errors will be encoded like this:
  36
  37     {"id": 23, "error": "Simple error message"}
  38
  39     See http://www.jsonrpc.org/ for the inspiration of the protocol.
  40
  41     """
  42
  43     def __init__(self, stdin=None, stdout=None):
  44         """Return a new JSON-RPC server object.
  45
  46         It will read lines of JSON data from stdin, and write the
  47         responses to stdout.
  48
  49         """
  50         if stdin is None:
  51             self.stdin = sys.stdin
  52         else:
  53             self.stdin = stdin
  54         if stdout is None:
  55             self.stdout = sys.stdout
  56         else:
  57             self.stdout = stdout
  58
  59     def read_json(self):
  60         """Read a single line and decode it as JSON.
  61
  62         Can raise an EOFError() when the input source was closed.
  63
  64         """
  65         line = self.stdin.readline()
  66         if line == '':
  67             raise EOFError()
  68         return json.loads(line)
  69
  70     def write_json(self, **kwargs):
  71         """Write an JSON object on a single line.
  72
  73         The keyword arguments are interpreted as a single JSON object.
  74         It's not possible with this method to write non-objects.
  75
  76         """
  77         from elpy.json_encoder import JSONEncoder
  78         serialized_value = JSONEncoder().encode(kwargs)
  79         self.stdout.write(serialized_value + "\n")
  80         self.stdout.flush()
  81
  82     def handle_request(self):
  83         """Handle a single JSON-RPC request.
  84
  85         Read a request, call the appropriate handler method, and
  86         return the encoded result. Errors in the handler method are
  87         caught and encoded as error objects. Errors in the decoding
  88         phase are not caught, as we can not respond with an error
  89         response to them.
  90
  91         """
  92         request = self.read_json()
  93         if 'method' not in request:
  94             raise ValueError("Received a bad request: {0}"
  95                              .format(request))
  96         method_name = request['method']
  97         request_id = request.get('id', None)
  98         params = request.get('params') or []
  99         try:
 100             method = getattr(self, "rpc_" + method_name, None)
 101             if method is not None:
 102                 result = method(*params)
 103             else:
 104                 result = self.handle(method_name, params)
 105             if request_id is not None:
 106                 self.write_json(result=result,
 107                                 id=request_id)
 108         except Fault as fault:
 109             error = {"message": fault.message,
 110                      "code": fault.code}
 111             if fault.data is not None:
 112                 error["data"] = fault.data
 113             self.write_json(error=error, id=request_id)
 114         except Exception as e:
 115             error = {"message": str(e),
 116                      "code": 500,
 117                      "data": {"traceback": traceback.format_exc()}}
 118             self.write_json(error=error, id=request_id)
 119
 120     def handle(self, method_name, args):
 121         """Handle the call to method_name.
 122
 123         You should overwrite this method in a subclass.
 124         """
 125         raise Fault("Unknown method {0}".format(method_name))
 126
 127     def serve_forever(self):
 128         """Serve requests forever.
 129
 130         Errors are not caught, so this is a slight misnomer.
 131
 132         """
 133         while True:
 134             try:
 135                 self.handle_request()
 136             except (KeyboardInterrupt, EOFError, SystemExit):
 137                 break
 138
 139
 140 class Fault(Exception):
 141     """RPC Fault instances.
 142
 143     code defines the severity of the warning.
 144
 145     2xx: Normal behavior lead to end of operation, i.e. a warning
 146     4xx: An expected error occurred
 147     5xx: An unexpected error occurred (usually includes a traceback)
 148     """
 149     def __init__(self, message, code=500, data=None):
 150         super(Fault, self).__init__(message)
 151         self.message = message
 152         self.code = code
 153         self.data = data