ethers-rlp

ethers-rlp

Handles the serialization and deserialization of the data in RLP (Recursive Length Prefix) format, which is extensively used in Ethereum's execution clients. The code is optimized for performance by minimizing the number of allocations and copying.

The RLP logic is implemented in RlpEncoder and RlpDecoder classes. They are written in way so that the actual structure of the data can be represented in code:

val rlp = RlpEncoder()

rlp.encodeList {
    encodeString("Hello")
    encodeString("World")

    encodeList {
        encodeString("Hello from")
        encodeString("nested list")
    }
}

The RlpEncodable and RlpDecodable interfaces are used to define the serialization and deserialization logic of custom data types. RlpEncodable is intended for serializing an actual instance of a type to RLP, while RlpDecodable acts as a factory to create an instance of a type from the RLP. Recommended pattern when working in Kotlin is to implement the encodable interface directly on the type, and the decodable interface on a companion object:

import java.math.BigInteger

data class MyData(val a: BigInteger, val b: Long) : RlpEncodable {
    override fun rlpEncode(rlp: RlpEncoder) {
        rlp.encodeList {
            encode(a)
            encode(b)
        }
    }

    companion object : RlpDecodable<MyData> {
        override fun rlpDecode(rlp: RlpDecoder): MyData {
            return rlp.decodeList {
                MyData(decodeBigInteger(), decodeLong())
            }
        }
    }
}