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#pragma once
// random2.hpp - Random number generation.
//
// Copyright © 2013 Ben Longbons <b.r.longbons@gmail.com>
//
// This file is part of The Mana World (Athena server)
//
// This program 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.
//
// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
#include "random.hpp"
#include "fwd.hpp"
#include <algorithm>
#include "../compat/iter.hpp"
namespace tmwa
{
namespace random_
{
namespace detail
{
struct RandomIterator
{
int bound;
int current;
bool frist;
void operator ++()
{
frist = false;
// TODO: reimplement in terms of LFSRs, so that certain
// blockage patterns don't favor adjacent cells.
current = current + 1;
if (current == bound)
current = 0;
}
int operator *()
{
return current;
}
};
inline
bool operator == (RandomIterator l, RandomIterator r)
{
return l.current == r.current && l.frist == r.frist;
}
inline
bool operator != (RandomIterator l, RandomIterator r)
{
return !(l == r);
}
}
/// Yield every cell from 0 .. bound - 1 in some order.
/// The starting position is random, but not the order itself.
///
/// Expected usage:
/// for (int i : random_::iterator(vec.size()))
/// if (vec[i].okay())
/// return frob(vec[i]);
inline
IteratorPair<detail::RandomIterator> iterator(int bound)
{
int current = random_::to(bound);
return
{
detail::RandomIterator{bound, current, true},
detail::RandomIterator{bound, current, false}
};
}
/// similar to std::random_shuffle(c.begin(), c.end()), but guaranteed
/// to use a good source of randomness.
template<class C>
void shuffle(C&& c)
{
std::random_shuffle(c.begin(), c.end(), random_::to);
}
} // namespace random_
} // namespace tmwa
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