62 lines
2.4 KiB
Markdown
62 lines
2.4 KiB
Markdown
# Vanillae RLP library
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This implements [Ethereum's RLP codec](https://zxq9.com/archives/2749)
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The decoded data ("decoded" from the perspective of the program using the data)
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is arbitrary-depth arbitrary-length lists-of-lists-of-...-binaries (lists and
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binaries are allowed to be empty). The encoded data is of course a single flat
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binary string.
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It has been tested against Ethereum's official Python implementation.
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You can see the methodology in [`tests/vrlp_testgen.erl`](tests/vrlp_testgen.erl):
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- 10,000 decoded data structures are generated at random
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- the test generator calls `vrlp:encode/1` to generate an encode/decode pair
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- assert that encode -> decode round trips properly in the `vrlp` module
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- print out an encode-decode pair as a python term to stdout
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- python program tests the encode-decode pairs against Ethereum's library
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The heart of the methodology is here:
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```erl
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% input: decoded_data
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% format a case as
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% {'decoded_data': <python term for rlist>,
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% 'encoded_bytes': bytes([B1, B2, B3, ...])}
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format_case_py(DecodedData_rlist) ->
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% EncodedData_bytes = rlp:encode(
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% DD_js = format_data_js(DecodedData_rlist),
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EncodedData_bytes = vrlp:encode(DecodedData_rlist),
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% assert encode -> decode round trips
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{DecodedData_rlist, <<>>} = vrlp:decode(EncodedData_bytes),
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EncodedBytes_py = format_bytes_py(EncodedData_bytes),
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DecodedData_py = format_data_py(DecodedData_rlist),
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[" {'decoded': ", DecodedData_py, ",\n",
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" 'encoded': ", EncodedBytes_py, "}"].
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```
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The Python side from [`tests/rlptests.py`](tests/rlptests.py):
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```python
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def main():
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all_encode_work = True
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all_decode_work = True
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for case in cases:
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decoded_data = case['decoded']
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encoded_bytes = case['encoded']
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real_encoded_bytes = rlp.encode(decoded_data)
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real_decoded_data = rlp.decode(encoded_bytes)
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# check if encode/decode works
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encode_works = (real_encoded_bytes == encoded_bytes)
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decode_works = (real_decoded_data == decoded_data)
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print('encode works: %s' % (encode_works))
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print('decode works: %s' % (decode_works))
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# update globals
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all_encode_work = all_encode_work and encode_works
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all_decode_work = all_decode_work and decode_works
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# print globals
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print('all encode work: %s' % (all_encode_work))
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print('all decode work: %s' % (all_decode_work))
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```
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