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// -*-c++-*-
// vim: set ft=cpp:
/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#ifndef cmext_iterator
#define cmext_iterator
#include <iterator>
#include <cm/type_traits>
namespace cm {
// checks if a type is an iterator type
template <typename I>
using is_iterator =
std::is_integral<typename std::iterator_traits<I>::difference_type>;
// checks if a type is an input iterator type
template <typename I>
using is_input_iterator =
std::is_base_of<std::input_iterator_tag,
typename std::iterator_traits<I>::iterator_category>;
// checks if a type is a range type: must have a difference_type type
template <typename Range>
using is_range = cm::bool_constant<
cm::is_iterator<decltype(std::declval<const Range>().begin())>::value &&
cm::is_iterator<decltype(std::declval<const Range>().end())>::value>;
// checks if a type is an input range type: must have methods begin() and end()
// returning an input iterator
template <typename Range>
using is_input_range =
#if defined(_MSC_VER) && _MSC_VER < 1920
// MS C++ is not able to evaluate complex type introspection,
// so use a simplified version
cm::is_input_iterator<typename Range::const_iterator>;
#else
cm::bool_constant<
cm::is_input_iterator<decltype(
std::declval<const Range>().begin())>::value &&
cm::is_input_iterator<decltype(std::declval<const Range>().end())>::value>;
#endif
} // namespace cm
#endif
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