libcruft-util/types/comparator.hpp
Danny Robson f6056153e3 rename root namespace from util to cruft
This places, at long last, the core library code into the same namespace
as the extended library code.
2018-08-05 14:42:02 +10:00

70 lines
1.9 KiB
C++

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2012-2017 Danny Robson <danny@nerdcruft.net>
*/
#ifndef UTIL_TYPES_COMPARATOR_HPP
#define UTIL_TYPES_COMPARATOR_HPP
#include <memory>
#include "../iterator.hpp"
namespace cruft::comparator {
///////////////////////////////////////////////////////////////////////////
/// Compares standard types that can be reduced to pointers.
template <typename T>
struct pointer {
constexpr
bool
operator() (const std::unique_ptr<T> &a, const std::unique_ptr<T> &b)
{
return a < b;
}
constexpr
bool
operator() (const T *a, const std::unique_ptr<T> &b)
{
return a < b.get ();
}
constexpr
bool
operator() (const std::unique_ptr<T> &a, const T *b)
{
return a.get () < b;
}
};
///////////////////////////////////////////////////////////////////////////
/// Provides a comparison interface for types exposing an index operator.
///
/// Will return true if the first parameter has the first index that
/// compares less than the second parameter. Useful for providing a total
/// order of coordinate types where this doesn't make sense by default.
///
/// \tparam T The container data type to compare. Must provide an index
/// operator.
template <typename T>
struct indexed {
constexpr
bool operator() (const T &a, const T &b) const
{
for (auto x: cruft::zip (a, b)) {
const auto &[i,j] = x; // BUG: clang-4.0: workaround for segfault.
if (i < j) return true;
if (i != j) return false;
}
return false;
}
};
}
#endif