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include/boost/lexical_cast/detail/is_character.hpp

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+// Copyright Kevlin Henney, 2000-2005.
+// Copyright Alexander Nasonov, 2006-2010.
+// Copyright Antony Polukhin, 2011-2025.
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// what:  lexical_cast custom keyword cast
+// who:   contributed by Kevlin Henney,
+//        enhanced with contributions from Terje Slettebo,
+//        with additional fixes and suggestions from Gennaro Prota,
+//        Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
+//        Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
+//        Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
+// when:  November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
+
+#ifndef BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
+#define BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
+
+#include <type_traits>
+
+#include <boost/config.hpp>
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#   pragma once
+#endif
+
+namespace boost { namespace detail {
+
+// returns true, if T is one of the character types
+template < typename T >
+using is_character = std::integral_constant<
+    bool,
+    std::is_same< T, char >::value ||
+#if !defined(BOOST_NO_STRINGSTREAM) && !defined(BOOST_NO_STD_WSTRING)
+    std::is_same< T, wchar_t >::value ||
+#endif
+#ifndef BOOST_NO_CXX11_CHAR16_T
+    std::is_same< T, char16_t >::value ||
+#endif
+#ifndef BOOST_NO_CXX11_CHAR32_T
+    std::is_same< T, char32_t >::value ||
+#endif
+    std::is_same< T, unsigned char >::value ||
+    std::is_same< T, signed char >::value
+>;
+
+}}
+
+#endif // BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
+