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/*!
@file
Defines `boost::hana::string`.
@copyright Louis Dionne 2013-2016
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_STRING_HPP
#define BOOST_HANA_STRING_HPP
#include <boost/hana/fwd/string.hpp>
#include <boost/hana/bool.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/make.hpp>
#include <boost/hana/detail/algorithm.hpp>
#include <boost/hana/detail/operators/adl.hpp>
#include <boost/hana/detail/operators/comparable.hpp>
#include <boost/hana/detail/operators/iterable.hpp>
#include <boost/hana/detail/operators/orderable.hpp>
#include <boost/hana/fwd/at.hpp>
#include <boost/hana/fwd/contains.hpp>
#include <boost/hana/fwd/core/tag_of.hpp>
#include <boost/hana/fwd/core/to.hpp>
#include <boost/hana/fwd/drop_front.hpp>
#include <boost/hana/fwd/equal.hpp>
#include <boost/hana/fwd/find.hpp>
#include <boost/hana/fwd/front.hpp>
#include <boost/hana/fwd/hash.hpp>
#include <boost/hana/fwd/is_empty.hpp>
#include <boost/hana/fwd/length.hpp>
#include <boost/hana/fwd/less.hpp>
#include <boost/hana/fwd/unpack.hpp>
#include <boost/hana/if.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/optional.hpp>
#include <boost/hana/type.hpp>
#include <utility>
#include <cstddef>
#include <type_traits>
BOOST_HANA_NAMESPACE_BEGIN
//////////////////////////////////////////////////////////////////////////
// string<>
//////////////////////////////////////////////////////////////////////////
//! @cond
template <char ...s>
struct string
: detail::operators::adl<string<s...>>
, detail::iterable_operators<string<s...>>
{ };
//! @endcond
template <char ...s>
struct tag_of<string<s...>> {
using type = string_tag;
};
//////////////////////////////////////////////////////////////////////////
// make<string_tag>
//////////////////////////////////////////////////////////////////////////
template <>
struct make_impl<string_tag> {
template <typename ...Chars>
static constexpr auto apply(Chars const& ...) {
return hana::string<hana::value<Chars>()...>{};
}
};
//////////////////////////////////////////////////////////////////////////
// BOOST_HANA_STRING
//////////////////////////////////////////////////////////////////////////
namespace string_detail {
template <typename S, std::size_t ...N>
constexpr string<S::get()[N]...>
prepare_impl(S, std::index_sequence<N...>)
{ return {}; }
template <typename S>
constexpr decltype(auto) prepare(S s) {
return prepare_impl(s,
std::make_index_sequence<sizeof(S::get()) - 1>{});
}
}
#define BOOST_HANA_STRING(s) \
(::boost::hana::string_detail::prepare([]{ \
struct tmp { \
static constexpr decltype(auto) get() { return s; } \
}; \
return tmp{}; \
}())) \
/**/
#ifdef BOOST_HANA_CONFIG_ENABLE_STRING_UDL
//////////////////////////////////////////////////////////////////////////
// _s user-defined literal
//////////////////////////////////////////////////////////////////////////
namespace literals {
template <typename CharT, CharT ...s>
constexpr auto operator"" _s() {
static_assert(std::is_same<CharT, char>::value,
"hana::string: Only narrow string literals are supported with "
"the _s string literal right now. See https://goo.gl/fBbKD7 "
"if you need support for fancier types of compile-time strings.");
return hana::string_c<s...>;
}
}
#endif
//////////////////////////////////////////////////////////////////////////
// Operators
//////////////////////////////////////////////////////////////////////////
namespace detail {
template <>
struct comparable_operators<string_tag> {
static constexpr bool value = true;
};
template <>
struct orderable_operators<string_tag> {
static constexpr bool value = true;
};
}
//////////////////////////////////////////////////////////////////////////
// to<char const*>
//////////////////////////////////////////////////////////////////////////
template <>
struct to_impl<char const*, string_tag> {
template <char ...c>
static constexpr char const c_string[sizeof...(c) + 1] = {c..., '\0'};
template <char ...c>
static constexpr char const* apply(string<c...> const&)
{ return c_string<c...>; }
};
template <char ...c>
constexpr char const to_impl<char const*, string_tag>::c_string[sizeof...(c) + 1];
//////////////////////////////////////////////////////////////////////////
// Comparable
//////////////////////////////////////////////////////////////////////////
template <>
struct equal_impl<string_tag, string_tag> {
template <typename S>
static constexpr auto apply(S const&, S const&)
{ return hana::true_c; }
template <typename S1, typename S2>
static constexpr auto apply(S1 const&, S2 const&)
{ return hana::false_c; }
};
//////////////////////////////////////////////////////////////////////////
// Orderable
//////////////////////////////////////////////////////////////////////////
template <>
struct less_impl<string_tag, string_tag> {
template <char ...s1, char ...s2>
static constexpr auto
apply(string<s1...> const&, string<s2...> const&) {
// We put a '\0' at the end only to avoid empty arrays.
constexpr char const c_str1[] = {s1..., '\0'};
constexpr char const c_str2[] = {s2..., '\0'};
return hana::bool_c<detail::lexicographical_compare(
c_str1, c_str1 + sizeof...(s1),
c_str2, c_str2 + sizeof...(s2)
)>;
}
};
//////////////////////////////////////////////////////////////////////////
// Foldable
//////////////////////////////////////////////////////////////////////////
template <>
struct unpack_impl<string_tag> {
template <char ...s, typename F>
static constexpr decltype(auto) apply(string<s...> const&, F&& f)
{ return static_cast<F&&>(f)(char_<s>{}...); }
};
template <>
struct length_impl<string_tag> {
template <char ...s>
static constexpr auto apply(string<s...> const&)
{ return hana::size_c<sizeof...(s)>; }
};
//////////////////////////////////////////////////////////////////////////
// Iterable
//////////////////////////////////////////////////////////////////////////
template <>
struct front_impl<string_tag> {
template <char x, char ...xs>
static constexpr auto apply(string<x, xs...> const&)
{ return hana::char_c<x>; }
};
template <>
struct drop_front_impl<string_tag> {
template <std::size_t N, char ...xs, std::size_t ...i>
static constexpr auto helper(string<xs...> const&, std::index_sequence<i...>) {
constexpr char s[] = {xs...};
return hana::string_c<s[i + N]...>;
}
template <char ...xs, typename N>
static constexpr auto apply(string<xs...> const& s, N const&) {
return helper<N::value>(s, std::make_index_sequence<
N::value < sizeof...(xs) ? sizeof...(xs) - N::value : 0
>{});
}
template <typename N>
static constexpr auto apply(string<> const& s, N const&)
{ return s; }
};
template <>
struct is_empty_impl<string_tag> {
template <char ...s>
static constexpr auto apply(string<s...> const&)
{ return hana::bool_c<sizeof...(s) == 0>; }
};
template <>
struct at_impl<string_tag> {
template <char ...s, typename N>
static constexpr auto apply(string<s...> const&, N const&) {
// We put a '\0' at the end to avoid an empty array.
constexpr char characters[] = {s..., '\0'};
constexpr auto n = N::value;
return hana::char_c<characters[n]>;
}
};
//////////////////////////////////////////////////////////////////////////
// Searchable
//////////////////////////////////////////////////////////////////////////
template <>
struct contains_impl<string_tag> {
template <char ...s, typename C>
static constexpr auto
helper(string<s...> const&, C const&, hana::true_) {
constexpr char const characters[] = {s..., '\0'};
constexpr char c = hana::value<C>();
return hana::bool_c<
detail::find(characters, characters + sizeof...(s), c)
!= characters + sizeof...(s)
>;
}
template <typename S, typename C>
static constexpr auto helper(S const&, C const&, hana::false_)
{ return hana::false_c; }
template <typename S, typename C>
static constexpr auto apply(S const& s, C const& c)
{ return helper(s, c, hana::bool_c<hana::Constant<C>::value>); }
};
template <>
struct find_impl<string_tag> {
template <char ...s, typename Char>
static constexpr auto apply(string<s...> const& str, Char const& c) {
return hana::if_(contains_impl<string_tag>::apply(str, c),
hana::just(c),
hana::nothing
);
}
};
//////////////////////////////////////////////////////////////////////////
// Hashable
//////////////////////////////////////////////////////////////////////////
template <>
struct hash_impl<string_tag> {
template <typename String>
static constexpr auto apply(String const&) {
return hana::type_c<String>;
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_STRING_HPP
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