ethane-abi 1.0.2

An alternative web3 abi parser library which aims the simplicity
Documentation 
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use super::utils::left_pad_to_32_bytes;
use super::Parameter;

use std::ops::Range;

pub fn encode_into(hash: &mut Vec<u8>, parameters: Vec<Parameter>) {
    let dynamic_offset = hash.len();
    let mut dynamic_type_map = Vec::<(usize, Range<usize>)>::with_capacity(parameters.len());
    for (i, param) in parameters.iter().enumerate() {
        if param.is_dynamic() {
            // save range where we will insert the data pointer since
            // we don't know (YET) where exactly the dynamic data will
            // start
            dynamic_type_map.push((i, hash.len()..hash.len() + 32));
            // append a 32 byte zero slice as a placeholder for our
            // future dynamic data pointer
            hash.extend_from_slice(&[0u8; 32]);
        } else {
            hash.extend_from_slice(&param.static_encode());
        }
    }

    for (index, range) in dynamic_type_map.into_iter() {
        // fill in the pointer offset to the dynamic data
        // the offset is measured from the start of the
        // outer data encoding
        let offset = (hash.len() - dynamic_offset).to_be_bytes();
        hash[range].copy_from_slice(&left_pad_to_32_bytes(&offset));
        match &parameters[index] {
            Parameter::Array(data) | Parameter::Tuple(data) => {
                // encode the length of the underlying dynamic data
                hash.extend_from_slice(&left_pad_to_32_bytes(&data.len().to_be_bytes()));
                encode_into(hash, data.to_vec());
            }
            _ => hash.extend_from_slice(&parameters[index].static_encode()),
        }
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use ethane_types::U256;
    use hex_literal::hex;

    #[test]
    #[rustfmt::skip]
    fn first_contract_abi() {
        let mut hash = vec![0xaa, 0xbb, 0xcc, 0xdd];
        encode_into(
            &mut hash,
            vec![Parameter::from(69u32), Parameter::from(true)],
        );
        assert_eq!(
            hash,
            vec![
                0xaa, 0xbb, 0xcc, 0xdd, // keccak signature
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0x45, // u32
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0x01, // bool
            ]
        );
    }

    #[test]
    #[rustfmt::skip]
    fn second_contract_abi() {
        let mut hash = vec![0x10, 0x11, 0x12, 0x13];
        encode_into(
            &mut hash,
            vec![Parameter::FixedArray(vec![
                Parameter::new_fixed_bytes(&"abc".as_bytes()),
                Parameter::new_fixed_bytes(&"def".as_bytes()),
            ])],
        );
        assert_eq!(
            hash,
            vec![
                0x10, 0x11, 0x12, 0x13, // keccak signature
                0x61, 0x62, 0x63, 0, 0, 0, 0, 0, // "abc"
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0x64, 0x65, 0x66, 0, 0, 0, 0, 0, // "def"
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0,
            ]
        );
    }

    #[test]
    #[rustfmt::skip]
    fn third_contract_abi() {
        let mut hash = vec![0xff, 0xee, 0x00, 0x07];
        encode_into(&mut hash, vec![
            Parameter::new_bytes(b"dave"),
            Parameter::from(true),
            Parameter::Array(vec![
                Parameter::from(U256::from_int_unchecked(1_u8)),
                Parameter::from(U256::from_int_unchecked(2_u8)),
                Parameter::from(U256::from_int_unchecked(3_u8)),
            ])
        ]);
        assert_eq!(hash, vec![
            0xff, 0xee, 0x00, 0x07, // signature
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x60, // bytes data will start at a 96 byte offset from signature
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x01, // bool true
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0xa0, // array data will start at a 160 byte offset from signature
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x04, // "dave" consists of 4 bytes
            0x64, 0x61, 0x76, 0x65, 0, 0, 0, 0, // "dave" as bytes
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, // byte array is padded right
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x03, // uint array has 3 elements
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x01, // first element
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x02, // second element
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0x03, // third element
        ]);
    }

    #[test]
    #[rustfmt::skip]
    fn fourth_contract_abi() {
        let mut hash = vec![0x8b, 0xe6, 0x52, 0x46];
        encode_into(&mut hash, vec![
            Parameter::from(U256::from_int_unchecked(0x123_u16)),
            Parameter::Array(vec![
               Parameter::from(U256::from_int_unchecked(0x456_u16)), // hex
               Parameter::from(U256::from_int_unchecked(0x789_u16)), // hex
            ]),
            Parameter::new_fixed_bytes(b"1234567890"),
            Parameter::new_bytes(b"Hello, world!"),
        ]);
        //assert_eq!(hash, hex!(
        let expected = hex!(
            "8be65246
            0000000000000000000000000000000000000000000000000000000000000123
            0000000000000000000000000000000000000000000000000000000000000080
            3132333435363738393000000000000000000000000000000000000000000000
            00000000000000000000000000000000000000000000000000000000000000e0
            0000000000000000000000000000000000000000000000000000000000000002
            0000000000000000000000000000000000000000000000000000000000000456
            0000000000000000000000000000000000000000000000000000000000000789
            000000000000000000000000000000000000000000000000000000000000000d
            48656c6c6f2c20776f726c642100000000000000000000000000000000000000"
            );
        for i in 0..9 {
            let start: usize = 4 + i * 32;
            let end: usize = start + 32;
            assert_eq!(hash[start..end], expected[start..end]);
        }
    }

    #[test]
    #[rustfmt::skip]
    fn fifth_contract_abi() {
        let mut hash = vec![1, 2, 3, 4];
        // encode g(uint[][],string[])
        encode_into(&mut hash, vec![
            Parameter::Array(vec![
                Parameter::Array(vec![
                    Parameter::from(U256::from_int_unchecked(1_u8)),
                    Parameter::from(U256::from_int_unchecked(2_u8)),
                ]),
                Parameter::Array(vec![
                    Parameter::from(U256::from_int_unchecked(3_u8)),
                ]),
            ]),
            Parameter::Array(vec![
                Parameter::from("one"),
                Parameter::from("two"),
                Parameter::from("three"),
            ]),
        ]);
        let expected = hex!(
            "01020304
            0000000000000000000000000000000000000000000000000000000000000040
            0000000000000000000000000000000000000000000000000000000000000140
            0000000000000000000000000000000000000000000000000000000000000002
            0000000000000000000000000000000000000000000000000000000000000040
            00000000000000000000000000000000000000000000000000000000000000a0
            0000000000000000000000000000000000000000000000000000000000000002
            0000000000000000000000000000000000000000000000000000000000000001
            0000000000000000000000000000000000000000000000000000000000000002
            0000000000000000000000000000000000000000000000000000000000000001
            0000000000000000000000000000000000000000000000000000000000000003
            0000000000000000000000000000000000000000000000000000000000000003
            0000000000000000000000000000000000000000000000000000000000000060
            00000000000000000000000000000000000000000000000000000000000000a0
            00000000000000000000000000000000000000000000000000000000000000e0
            0000000000000000000000000000000000000000000000000000000000000003
            6f6e650000000000000000000000000000000000000000000000000000000000
            0000000000000000000000000000000000000000000000000000000000000003
            74776f0000000000000000000000000000000000000000000000000000000000
            0000000000000000000000000000000000000000000000000000000000000005
            7468726565000000000000000000000000000000000000000000000000000000"
        );
        for i in 0..20 {
            let start: usize = 4 + i * 32;
            let end: usize = start + 32;
            assert_eq!(hash[start..end], expected[start..end]);
        }
    }
}