TrieCommon.h

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/*
        This file is part of cpp-ethereum.

        cpp-ethereum is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        cpp-ethereum is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once

#include "Common.h"
#include "RLP.h"

namespace dev
{

inline byte nibble(bytesConstRef _data, unsigned _i)
{
        return (_i & 1) ? (_data[_i / 2] & 15) : (_data[_i / 2] >> 4);
}

inline unsigned sharedNibbles(bytesConstRef _first, unsigned _beginFirst, unsigned _endFirst, bytesConstRef _second, unsigned _beginSecond, unsigned _endSecond)
{
        unsigned ret = 0;
        while (_beginFirst < _endFirst && _beginSecond < _endSecond && nibble(_first, _beginFirst) == nibble(_second, _beginSecond))
        {
                ++_beginFirst;
                ++_beginSecond;
                ++ret;
        }
        return ret;
}

struct NibbleSlice
{
        bytesConstRef data;
        unsigned offset;

        NibbleSlice(bytesConstRef _data = bytesConstRef(), unsigned _offset = 0): data(_data), offset(_offset) {}
        byte operator[](unsigned _index) const { return nibble(data, offset + _index); }
        unsigned size() const { return data.size() * 2 - offset; }
        bool empty() const { return !size(); }
        NibbleSlice mid(unsigned _index) const { return NibbleSlice(data, offset + _index); }
        void clear() { data.reset(); offset = 0; }

        bool contains(NibbleSlice _k) const { return shared(_k) == _k.size(); }
        unsigned shared(NibbleSlice _k) const { return sharedNibbles(data, offset, offset + size(), _k.data, _k.offset, _k.offset + _k.size()); }
        bool isEarlierThan(NibbleSlice _k) const
        {
                unsigned i = 0;
                for (; i < _k.size() && i < size(); ++i)
                        if (operator[](i) < _k[i])              // Byte is lower - we're earlier..
                                return true;
                        else if (operator[](i) > _k[i]) // Byte is higher - we're not earlier.
                                return false;
                if (i >= _k.size())                                     // Ran past the end of the prefix - we're == for the entire prefix - we're not earlier.
                        return false;
                return true;                                            // Ran out before the prefix had finished - we're earlier.
        }
        bool operator==(NibbleSlice _k) const { return _k.size() == size() && shared(_k) == _k.size(); }
        bool operator!=(NibbleSlice _s) const { return !operator==(_s); }
};

inline std::ostream& operator<<(std::ostream& _out, NibbleSlice const& _m)
{
        for (unsigned i = 0; i < _m.size(); ++i)
                _out << std::hex << (int)_m[i] << std::dec;
        return _out;
}

inline bool isLeaf(RLP const& _twoItem)
{
        assert(_twoItem.isList() && _twoItem.itemCount() == 2);
        auto pl = _twoItem[0].payload();
        return (pl[0] & 0x20) != 0;
}

inline NibbleSlice keyOf(bytesConstRef _hpe)
{
        if (!_hpe.size())
                return NibbleSlice(_hpe, 0);
        if (_hpe[0] & 0x10)
                return NibbleSlice(_hpe, 1);
        else
                return NibbleSlice(_hpe, 2);
}

inline NibbleSlice keyOf(RLP const& _twoItem)
{
        return keyOf(_twoItem[0].payload());
}

byte uniqueInUse(RLP const& _orig, byte except);
std::string hexPrefixEncode(bytes const& _hexVector, bool _leaf = false, int _begin = 0, int _end = -1);
std::string hexPrefixEncode(bytesConstRef _data, bool _leaf, int _beginNibble, int _endNibble, unsigned _offset);
std::string hexPrefixEncode(bytesConstRef _d1, unsigned _o1, bytesConstRef _d2, unsigned _o2, bool _leaf);

inline std::string hexPrefixEncode(NibbleSlice _s, bool _leaf, int _begin = 0, int _end = -1)
{
        return hexPrefixEncode(_s.data, _leaf, _begin, _end, _s.offset);
}

inline std::string hexPrefixEncode(NibbleSlice _s1, NibbleSlice _s2, bool _leaf)
{
        return hexPrefixEncode(_s1.data, _s1.offset, _s2.data, _s2.offset, _leaf);
}

}