Add support for multiple contract methods with same name

[rinat-enikeev]

Motivation: given ABI with multiple methods with same name and different input count [example], add ability to select correct method.

Implementation: instead of just first method - select by number of input parameters.

[JeneaVranceanu]

@yaroslavyaroslav LGTM
Ready to be merged.

[janndriessen]

Correct me if I'm wrong but I think this won't work for methods where there is multiple overloads but with the same parameters amount. As far as I understand this exists and is possible in solidity: https://docs.soliditylang.org/en/v0.4.21/contracts.html#overload-resolution-and-argument-matching

contract A {
    function f(uint8 _in) public pure returns (uint8 out) {
        out = _in;
    }

    function f(uint256 _in) public pure returns (uint256 out) {
        out = _in;
    }
}

[JeneaVranceanu]

It must work. Some time ago the support for function overloading was added and now it all depends on the method value that you pass in. As per docs for the methods (see here the source):

Functions are mapped to:
- name, like `getData` that is defined in ``ABI/Element/Function/name``;
- name with input parameters that is a combination of ``ABI/Element/Function/name`` and
``ABI/Element/Function/inputs``, e.g. `getData(bytes32)`;
- and 4 bytes signature `0xffffffff` (expected to be lowercased).
The mapping by name (e.g. `getData`) is the one most likely expected to return arrays with
more than one entry due to the fact that solidity allows method overloading.

[JeneaVranceanu]

So per your example if you pass in f as a function name you will get two result and the first one will be picked while you probably expect the second one (let's think that just for the sake of example).

But if you specify the full function selector which includes input types (e.g. f(uint8)) - you will get 0 or 1 results in the returned array depending on the availability of such function in the ABI of a smart contract.
If method ID is passed (which is 4 bytes of sha3 keccak256 of function name and it's parameters) you will get 0 or more results as some clashes can still happen but most of the time it should be 0 or 1 because it's somewhat rare to have first 4 bytes of two hashes of two different functions in the same smart contract to clash.

Note: if you'll try to parse ABI that has two functions with the same name and input type but different output the parsing of ABI will fail. Just saying.

[yaroslavyaroslav]

You need to press some button that means that PR passed your review. For now it's unable to merge any without at least one team members approve @JeneaVranceanu @janndriessen

[JeneaVranceanu]

You need to press some button that means that PR passed your review. For now it's unable to merge any without at least one team members approve @JeneaVranceanu @janndriessen

Hm, I thought that I approved it.
Now it's approved for sure.