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93 lines
3.1 KiB
Python
93 lines
3.1 KiB
Python
# Copyright 2023 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from bumble import core
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class AtParsingError(core.InvalidPacketError):
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"""Error raised when parsing AT commands fails."""
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def tokenize_parameters(buffer: bytes) -> list[bytes]:
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"""Split input parameters into tokens.
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Removes space characters outside of double quote blocks:
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T-rec-V-25 - 5.2.1 Command line general format: "Space characters (IA5 2/0)
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are ignored [..], unless they are embedded in numeric or string constants"
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Raises AtParsingError in case of invalid input string."""
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tokens: list[bytearray] = []
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in_quotes = False
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token = bytearray()
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for b in buffer:
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char = bytearray([b])
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if in_quotes:
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token.extend(char)
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if char == b'"':
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in_quotes = False
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tokens.append(token[1:-1])
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token = bytearray()
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else:
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match char:
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case b' ':
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pass
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case b',' | b')':
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tokens.append(token)
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tokens.append(char)
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token = bytearray()
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case b'(':
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if len(token) > 0:
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raise AtParsingError("open_paren following regular character")
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tokens.append(char)
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case b'"':
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if len(token) > 0:
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raise AtParsingError("quote following regular character")
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in_quotes = True
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token.extend(char)
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case _:
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token.extend(char)
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tokens.append(token)
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return [bytes(token) for token in tokens if len(token) > 0]
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def parse_parameters(buffer: bytes) -> list[bytes | list]:
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"""Parse the parameters using the comma and parenthesis separators.
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Raises AtParsingError in case of invalid input string."""
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tokens = tokenize_parameters(buffer)
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accumulator: list[list] = [[]]
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current: bytes | list = b''
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for token in tokens:
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match token:
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case b',':
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accumulator[-1].append(current)
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current = b''
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case b'(':
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accumulator.append([])
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case b')':
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if len(accumulator) < 2:
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raise AtParsingError("close_paren without matching open_paren")
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accumulator[-1].append(current)
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current = accumulator.pop()
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case _:
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current = token
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accumulator[-1].append(current)
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if len(accumulator) > 1:
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raise AtParsingError("missing close_paren")
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return accumulator[0]
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