generated from mwc/lab_compression
55 lines
1.6 KiB
Python
55 lines
1.6 KiB
Python
import string
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import codecs
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from easybits import Bits
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allowed_characters = string.ascii_letters + string.digits
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def encode(text):
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"""A (very) lossy encoder which only saves ASCII letters, numbers, and spaces.
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Everything else is discarded. All whitespace (e.g. tabs) is converted into spaces.
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"""
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ascii_characters = []
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last_character_was_space = False
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for char in text:
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if char in allowed_characters:
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ascii_characters.append(char)
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last_character_was_space = False
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elif char in string.whitespace and not last_character_was_space:
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ascii_characters.append(' ')
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last_character_was_space = True
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ascii_text = ''.join(ascii_characters)
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return Bits(ascii_text).bytes
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def decode(data):
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"""A decoder which reads bytes and returns (string, length),
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where length is the length of bytes consumed
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"""
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text = ""
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for i, byte in enumerate(data):
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try:
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text += Bits(byte, length=8).ascii
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except OverflowError:
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print(i, byte)
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print(text + '|')
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print("Error")
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breakpoint()
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return text
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def register_codec(encode, decode, name):
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"""Registers a codec so that it can later be used to encode
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or decode strings and bytes.
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"""
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def encode_wrapper(text):
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return encode(text), len(text)
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def decode_wrapper(data):
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return decode(data), len(data)
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def search_for_codec(query):
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if query == name:
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return codecs.CodecInfo(encode_wrapper, decode_wrapper, name=name)
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codecs.register(search_for_codec)
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register_codec(encode, decode, "alphanumeric")
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