compare.sol

import "./BytesUtils.sol";
import "./RRUtils.sol";

contract Test {
    using BytesUtils for *;
    using RRUtils for *;
    bytes public foo;
    event Logger(string name);
    event LoggerBytes(bytes name);
    event LoggerInt(uint label);

    // 0x0378797a00  = 'xyz.'
    // 0x066274686c61620378797a00  = 'bthlab.xyz.'
    // 0x066574686c61620378797a00  = 'ethlab.xyz.'
    // a: 'bthlab.xyz.' b: 'xyz.', 
    // [6, 98, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0], [3, 120, 121, 122, 0]
    // a: 'bthlab.xyz.' b: 'ethlab.xyz.' 
    // [6, 98, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0], [6, 101, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0]
    // [6, 101, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0], [6, 98, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0]
    // [6, 101, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0], [6, 101, 116, 104, 108, 97, 98, 3, 120, 121, 122, 0]
    function compare(bytes a, bytes b) public returns (int) {
        // when both are '.'
        if (keccak256(a) == keccak256('') && keccak256(b) == keccak256('')){
          return 0;
        }

        BytesUtils.Slice memory aSlice = a.toSlice();
        BytesUtils.Slice memory bSlice = b.toSlice();

        // getting head
        BytesUtils.Slice memory aHead;
        BytesUtils.Slice memory bHead;
        BytesUtils.Slice memory aTail;
        BytesUtils.Slice memory bTail;
        (aHead, aTail) = headAndTail(aSlice);
        (bHead, bTail) = headAndTail(bSlice);
        //uint result = compareTail(aTail, bTail);
        uint result = 0;
        if(result == 0){
            return aHead.compare(bHead);
        }
    }

    function headAndTail(BytesUtils.Slice aSlice) internal returns(BytesUtils.Slice head, BytesUtils.Slice tail){
        uint aHeadLength =  aSlice.uint8At(0);
        BytesUtils.Slice memory aHead;
        aHead.copyFrom(aSlice).s(1,aHeadLength);
        // getting tail
        BytesUtils.Slice memory aTail;
        aTail.copyFrom(aSlice).s(1 + aHeadLength, aSlice.len);
        return (aHead, aTail);
    }
}