902 lines
29 KiB
C++
902 lines
29 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_VIEW_HPP
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#define CRUFT_UTIL_VIEW_HPP
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#include "annotation.hpp"
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#include "cast.hpp"
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#include "types/traits.hpp"
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#include "maths.hpp"
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#include "platform.hpp"
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#include <cstdlib>
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#include <iosfwd>
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#include <string>
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#include <cstring>
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#include <stdexcept>
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#include <iterator>
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#include <type_traits>
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namespace cruft {
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template <typename BeginT, typename EndT = BeginT>
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struct view {
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public:
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using begin_type = BeginT;
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using end_type = EndT;
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//---------------------------------------------------------------------
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using value_type = typename std::iterator_traits<
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remove_restrict_t<BeginT>
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>::value_type;
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using size_type = size_t;
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//---------------------------------------------------------------------
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constexpr
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view (const BeginT &first, const EndT &last) noexcept:
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m_begin (first),
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m_end (last)
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{
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if constexpr (cruft::is_orderable_v<BeginT> && cruft::is_orderable_v<EndT>) {
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CHECK_LE (m_begin, m_end);
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}
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}
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template <
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typename ContainerT,
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typename = std::void_t<
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decltype (std::declval<ContainerT&> ().begin ()),
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decltype (std::declval<ContainerT&> ().end ())
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>
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>
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view (ContainerT &rhs) noexcept (
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noexcept (std::declval<ContainerT> ().begin ()) &&
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noexcept (std::declval<ContainerT> ().end ())
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)
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: view (rhs.begin (), rhs.end ())
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{ ; }
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template <
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typename ContainerT,
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typename = std::void_t<
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decltype (std::declval<ContainerT const&> ().begin ()),
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decltype (std::declval<ContainerT const&> ().end ())
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>
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>
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view (const ContainerT &rhs):
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view (rhs.begin (), rhs.end ())
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{ ; }
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//---------------------------------------------------------------------
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// cosntruction from pointer/size represenations for ease of use with
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// legacy C code.
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template <
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typename CountT,
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typename = std::enable_if_t<std::is_integral_v<CountT>,void>
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>
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view (
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const BeginT &_begin,
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CountT _size
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):
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view (_begin, _begin + _size)
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{ ; }
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//---------------------------------------------------------------------
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// implicit conversion from const pointer const views to const pointer views
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template <
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typename ValueT,
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typename = std::enable_if_t<
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std::is_same_v<BeginT, const ValueT**> &&
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std::is_same_v<EndT, const ValueT**>
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>
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>
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view (const view<const ValueT*const*,const ValueT*const*> &rhs):
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view (
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const_cast<const ValueT**> (rhs.begin ()),
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const_cast<const ValueT**> (rhs.end ())
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)
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{ ; }
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//---------------------------------------------------------------------
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// implicit conversion from pointer views to const pointer views
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template <
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typename ValueT,
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typename = std::enable_if_t<
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std::is_same_v<BeginT, const ValueT*> &&
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std::is_same_v<EndT, const ValueT*>
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>
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>
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view (const view<ValueT*,ValueT*> &rhs):
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view (rhs.begin (), rhs.end ())
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{ ; }
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//---------------------------------------------------------------------
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// explicitly cater for the char array case so that we don't
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// accidentally include the trailing null in the data.
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template <std::size_t N>
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view (const char (&value)[N]):
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view {std::begin (value), std::begin (value) + N - 1}
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{
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static_assert (N > 0);
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}
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//---------------------------------------------------------------------
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view (const char *str):
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view { str, str + strlen (str) }
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{ ; }
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//---------------------------------------------------------------------
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view (char *str):
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view (str, str + strlen (str))
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{ ; }
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//---------------------------------------------------------------------
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template <std::size_t N>
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view (char (&value)[N]):
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view {std::begin (value), std::begin (value) + N - 1}
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{
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static_assert (N > 0);
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}
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//---------------------------------------------------------------------
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template <std::size_t N, typename ValueT>
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view (const ValueT(&value)[N]):
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view {std::begin (value), std::end (value)}
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{ ; }
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//---------------------------------------------------------------------
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template <std::size_t N, typename ValueT>
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view (ValueT(&value)[N]):
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view {std::begin (value), std::end (value)}
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{ ; }
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//---------------------------------------------------------------------
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constexpr view (const view &) noexcept = default;
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constexpr view (view &&) noexcept = default;
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view& operator= (const view &rhs) noexcept = default;
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view& operator= (view &&rhs) noexcept = default;
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//---------------------------------------------------------------------
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// allow null construction of views where IteratorT is constructible
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// from nullptr_t
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//
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// ideally we would avoid exposing this as it promotes use of nulls but
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// it simplifies construction of views that are data members of classes
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// when we may not immediately know the values we should contain.
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constexpr view (std::nullptr_t) noexcept:
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view {nullptr,nullptr}
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{ ; }
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//---------------------------------------------------------------------
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template <typename CharT, typename Traits, typename Allocator>
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view (std::basic_string<CharT,Traits,Allocator> &val):
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view (std::data (val), std::size (val))
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{ ; }
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//---------------------------------------------------------------------
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template <typename CharT, typename Traits, typename Allocator>
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view (const std::basic_string<CharT,Traits,Allocator> &val):
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view (std::data (val), std::size (val))
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{ ; }
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//---------------------------------------------------------------------
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template <typename ValueT, typename AllocatorT>
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view (const std::vector<ValueT,AllocatorT> &rhs):
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view (std::data (rhs), std::size (rhs))
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{ ; }
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//---------------------------------------------------------------------
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template <typename ValueT, typename AllocatorT>
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view (std::vector<ValueT,AllocatorT> &rhs):
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view (std::data (rhs), std::size (rhs))
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{ ; }
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//---------------------------------------------------------------------
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template <typename ValueT, std::size_t N>
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view (std::array<ValueT,N> &rhs):
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view (std::data (rhs), std::size (rhs))
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{ ; }
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//---------------------------------------------------------------------
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template <typename ValueT, std::size_t N>
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view (const std::array<ValueT,N> &rhs):
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view (std::data (rhs), std::size (rhs))
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{ ; }
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///////////////////////////////////////////////////////////////////////
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constexpr BeginT begin (void) noexcept { return m_begin; }
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constexpr EndT end (void) noexcept { return m_end; }
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constexpr BeginT begin (void) const noexcept { return m_begin; }
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constexpr EndT end (void) const noexcept { return m_end; }
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//---------------------------------------------------------------------
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constexpr BeginT cbegin (void) const noexcept { return m_begin; }
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constexpr EndT cend (void) const noexcept { return m_end; }
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//---------------------------------------------------------------------
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auto data (void) noexcept { return begin (); }
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auto data (void) const noexcept { return begin (); }
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///////////////////////////////////////////////////////////////////////
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/// Returns true if the size of the view is zero.
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constexpr bool
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empty (void) const noexcept
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{
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return m_begin == m_end;
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}
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///--------------------------------------------------------------------
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/// Returns the number of items in the view.
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constexpr auto
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size (void) const noexcept
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{
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return static_cast<size_type> (std::distance (m_begin, m_end));
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}
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///--------------------------------------------------------------------
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/// Returns a subview of the first `count` elements of this view.
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[[nodiscard]] constexpr auto
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redim (size_type count) const
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{
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assert (count > 0);
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if (count > size ())
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throw std::invalid_argument ("redim to higher size not allowed");
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return view { m_begin, m_begin + count };
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};
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///--------------------------------------------------------------------
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/// Returns two subviews split at `pos`.
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///
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/// The first view extends from `begin` to `pos`, and the second view
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/// extends from `pos` to `end`.
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[[nodiscard]] constexpr std::pair<
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view<BeginT,BeginT>,
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view<BeginT,EndT>
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>
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split (BeginT pos) const
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{
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return {
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{ m_begin, pos },
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{ pos, m_end }
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};
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}
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///--------------------------------------------------------------------
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template <
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typename IndexT,
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typename = std::enable_if_t<std::is_integral_v<IndexT>>
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>
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[[nodiscard]] constexpr auto
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split (IndexT idx) const
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{
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auto last = m_begin;
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std::advance (last, idx);
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return split (last);
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}
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//---------------------------------------------------------------------
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// slices a view using python indexing semantics. ie,
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// "abc".slice(0, 3) == "abc"
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// "abc".slice(0, -1) == "abc"
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// "abc".slice(0, -2) == "ab"
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template <typename IndexA, typename IndexB>
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[[nodiscard]]constexpr auto
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slice (IndexA a, IndexB b) const
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{
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auto first = m_begin;
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auto last = m_begin;
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std::advance (first, a < 0 ? size () + a + 1 : a);
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std::advance (last, b < 0 ? size () + b + 1 : b);
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return view { first, last };
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}
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//---------------------------------------------------------------------
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template <
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typename IndexT,
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typename = std::enable_if_t<std::is_integral_v<IndexT>>
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>
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constexpr auto
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head (IndexT idx)
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{
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return std::get<0> (split (idx));
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}
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//---------------------------------------------------------------------
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template <
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typename IndexT,
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typename = std::enable_if_t<std::is_integral_v<IndexT>>
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>
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constexpr auto
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tail (IndexT idx)
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{
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return std::get<1> (split (idx));
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}
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//---------------------------------------------------------------------
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template <
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typename IndexT,
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typename = std::enable_if_t<std::is_integral_v<IndexT>>
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>
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constexpr auto
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tail (IndexT idx) const
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{
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return std::get<1> (split (idx));
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}
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//---------------------------------------------------------------------
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template <
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typename IndexT,
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typename = std::enable_if_t<std::is_integral_v<IndexT>>
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>
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[[nodiscard]] constexpr auto
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consume (IndexT count) const
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{
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auto [a,b] = split (count);
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(void)a;
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return b;
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}
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//---------------------------------------------------------------------
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[[nodiscard]] constexpr view<BeginT,EndT>
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consume (view<BeginT,EndT> prefix) const
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{
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assert (prefix.begin () == begin ());
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assert (prefix.end () < end ());
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return { prefix.end (), end () };
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}
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[[nodiscard]] constexpr view<BeginT,EndT>
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consume (const BeginT pos) const
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{
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return { pos, end () };
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}
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///////////////////////////////////////////////////////////////////////
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/// Explicitly cast to a view with different iterator types.
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///
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/// The source and destination iterator types must be:
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/// * pointers
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/// * alignable
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///
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/// It is undefined behaviour to cast with begin and/or end iterators
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/// that do not have natural alignment. Instrumented builds _may_
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/// provide diagnostics or assertions in this case.
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///
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/// \tparam ValueT The new iterator type
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/// \return A view that uses the new iterator type
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template <
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typename ValueT,
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typename = std::enable_if_t<
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// We can only convert views that use pointer iterators
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std::is_pointer_v<BeginT> &&
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std::is_pointer_v<EndT> &&
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std::is_same_v<BeginT,EndT> &&
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std::is_pointer_v<ValueT> &&
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// The values they point to must allow for alignment in one
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// direction or another.
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(
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sizeof (typename std::iterator_traits<BeginT>::value_type) %
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sizeof (typename std::iterator_traits<ValueT>::value_type) == 0 ||
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sizeof (typename std::iterator_traits<ValueT>::value_type) %
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sizeof (typename std::iterator_traits<BeginT>::value_type) == 0
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)
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>
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>
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view<ValueT>
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cast (void) const
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{
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return {
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cast::alignment<ValueT> (m_begin),
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cast::alignment<ValueT> (m_end)
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};
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}
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///////////////////////////////////////////////////////////////////////
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constexpr auto&&
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operator[] (size_t idx) noexcept
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{
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return *std::next (begin (), idx);
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}
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//---------------------------------------------------------------------
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constexpr auto&&
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operator[] (size_t idx) const noexcept
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{
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return *std::next (begin (), idx);
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}
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private:
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///////////////////////////////////////////////////////////////////////
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BeginT m_begin;
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EndT m_end;
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};
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//-------------------------------------------------------------------------
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template <typename ValueT, std::size_t N>
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view (ValueT(&)[N]) -> view<ValueT*,ValueT*>;
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//-------------------------------------------------------------------------
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view (const char*) -> view<const char*, const char*>;
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view (char*) -> view<char*>;
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//-------------------------------------------------------------------------
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template <
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typename IteratorT,
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typename SizeT,
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typename = std::enable_if_t<
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std::is_integral_v<SizeT>
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>
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>
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view (IteratorT, SizeT) -> view<IteratorT,IteratorT>;
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template <typename CharT, typename Traits, typename Allocator>
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view (std::basic_string<CharT,Traits,Allocator> &) -> view<typename Allocator::pointer>;
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template <typename CharT, typename Traits, typename Allocator>
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view (const std::basic_string<CharT,Traits,Allocator> &) -> view<typename Allocator::const_pointer>;
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template <typename ValueT, typename AllocatorT>
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view (std::vector<ValueT,AllocatorT>&) -> view<typename AllocatorT::pointer>;
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template <typename ValueT, typename AllocatorT>
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view (const std::vector<ValueT,AllocatorT>&) -> view<typename AllocatorT::const_pointer>;
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template <typename ValueT, std::size_t N>
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view (std::array<ValueT,N>&) -> view<ValueT*>;
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template <typename ValueT, std::size_t N>
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view (const std::array<ValueT,N>&) -> view<const ValueT*>;
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template <typename ContainerT>
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view (ContainerT&) -> view<
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decltype (std::declval<ContainerT&> ().begin ()),
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decltype (std::declval<ContainerT&> ().end ())
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>;
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template <typename ContainerT>
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view (const ContainerT&) -> view<
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decltype (std::declval<ContainerT const&> ().begin ()),
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decltype (std::declval<ContainerT const&> ().end ())
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>;
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// base + count constructor
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template <typename BeginT>
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view (BeginT, std::uint64_t count) -> view<BeginT,BeginT>;
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template <typename BeginT>
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view (BeginT, std::uint32_t count) -> view<BeginT,BeginT>;
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///////////////////////////////////////////////////////////////////////////
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template <typename ValueT, size_t N>
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auto
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make_view (const ValueT (&arr)[N])
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{
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return view<const ValueT*> (arr + 0, arr + N);
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}
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//-------------------------------------------------------------------------
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template <typename ContainerT>
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auto
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make_view (ContainerT &t)
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{
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return view { std::begin (t), std::end (t) };
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}
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//-------------------------------------------------------------------------
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template <typename ContainerT>
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auto
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make_view (const ContainerT &t)
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{
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return view { std::cbegin (t), std::cend (t) };
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}
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//-------------------------------------------------------------------------
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// disable the possibility of creating a view to a temporary. note that
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// this only works if an lval version has already been defined otherwise
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// universal reference rules will capture both lval and rval here.
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template <typename ContainerT>
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auto
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make_view (ContainerT&&) = delete;
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///////////////////////////////////////////////////////////////////////////
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template <typename ContainerT>
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auto
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make_cview (const ContainerT &t)
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{
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return make_view (t);
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//return view<decltype(std::cbegin (t))> { std::cbegin (t), std::cend (t) };
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}
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//-------------------------------------------------------------------------
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template <typename BeginT, typename EndT>
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auto
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make_view (BeginT first, EndT last)
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{
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return view<BeginT, EndT> {first, last};
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}
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//-------------------------------------------------------------------------
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template <typename ValueT>
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auto
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make_cview (ValueT *first, ValueT *last)
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{
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return view<const ValueT*> {first, last};
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}
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///////////////////////////////////////////////////////////////////////////
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inline
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view<const char*> make_view (const char *str)
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{
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return { str, str + strlen (str) };
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}
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//-------------------------------------------------------------------------
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inline
|
|
view<char*> make_view (char *str)
|
|
{
|
|
return { str, str + strlen (str) };
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <typename CharT, typename TraitsT, typename AllocT>
|
|
view<const CharT*>
|
|
make_view (const std::basic_string<CharT,TraitsT,AllocT> &str)
|
|
{
|
|
return {
|
|
std::data (str),
|
|
std::data (str) + std::size (str)
|
|
};
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <typename CharT, typename TraitsT, typename AllocT>
|
|
view<CharT*>
|
|
make_view (std::basic_string<CharT,TraitsT,AllocT> &str)
|
|
{
|
|
return {
|
|
std::data (str),
|
|
std::data (str) + std::size (str)
|
|
};
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <typename CharT, typename TraitsT, typename AllocT>
|
|
view<const CharT*>
|
|
make_view (const std::basic_string<CharT,TraitsT,AllocT>&&) = delete;
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <typename CharT, typename TraitsT, typename AllocT>
|
|
view<CharT*>
|
|
make_view (std::basic_string<CharT,TraitsT,AllocT>&&) = delete;
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// Calculates a word oriented view over an arbitrary type
|
|
///
|
|
/// Useful for passing in memory structures to file descriptors and the
|
|
/// like. but the consequences of endian conversion is on the user...
|
|
///
|
|
/// We have to be careful that rval-references and other temporaries aren't
|
|
/// accepted in this signature.
|
|
template <
|
|
typename WordT = std::byte const,
|
|
typename T
|
|
>
|
|
cruft::view<WordT*>
|
|
make_byte_view (T &t)
|
|
{
|
|
static_assert (sizeof (T) % sizeof (WordT) == 0);
|
|
static_assert (std::is_const_v<T> ? std::is_const_v<WordT> : true);
|
|
|
|
return view {
|
|
cast::alignment<WordT*> (&t),
|
|
sizeof (T) / sizeof (WordT)
|
|
};
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// Returns a reference to a value of the designated type at the front of
|
|
/// the word-view. if there is insufficient data for the extraction an
|
|
/// exception will be thrown.
|
|
///
|
|
/// There are no validity or other checks performed on the returned data
|
|
/// this is deliberate, so that the function is safe to call on user
|
|
/// supplied data during parsing routines. it is up to the user to ensure
|
|
/// the object is valid.
|
|
///
|
|
/// The buffer object is advanced in place so that it no longer covers
|
|
/// the extract value
|
|
///
|
|
/// It is assumed the user has taken care of alignment concerns
|
|
template <
|
|
typename ValueT,
|
|
typename WordT,
|
|
// Only allow calls if the value is a multiple of the word size. It's
|
|
// useful to allow non-unit words for areas like TCP/IP which tend to
|
|
// operate on u16 words.
|
|
typename = std::enable_if_t<sizeof (ValueT) % sizeof (WordT) == 0>
|
|
>
|
|
ValueT const&
|
|
extract (view<WordT const*> &buffer)
|
|
{
|
|
if (unlikely (sizeof (ValueT) > buffer.size () * sizeof (WordT)))
|
|
throw std::runtime_error ("insufficient data for extraction");
|
|
|
|
auto const ptr = cast::alignment<ValueT const*> (buffer.data ());
|
|
buffer = buffer.consume (sizeof (ValueT) / sizeof (WordT));
|
|
return *ptr;
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// extracts an object of a specified type from the front of a byte-view.
|
|
///
|
|
/// in contrast to 'extract' this will always copy the bytes out from the
|
|
/// view, making the operation alignment safe.
|
|
template <
|
|
typename ValueT,
|
|
typename WordT,
|
|
typename = std::enable_if_t<sizeof (ValueT) % sizeof(WordT) == 0>
|
|
>
|
|
ValueT
|
|
read (view<WordT*> &buffer)
|
|
{
|
|
// We're going to use memcpy which requires that the type is
|
|
// trivially copyable.
|
|
static_assert (std::is_trivially_copyable_v<ValueT>);
|
|
|
|
if (unlikely (sizeof (ValueT) > buffer.size () * sizeof (WordT)))
|
|
throw std::runtime_error ("insufficient data for extraction");
|
|
|
|
std::aligned_storage_t<sizeof(ValueT),alignof(ValueT)> bytes;
|
|
memcpy (&bytes, buffer.data (), sizeof (ValueT));
|
|
buffer = buffer.consume (sizeof (ValueT) / sizeof (WordT));
|
|
return *reinterpret_cast<ValueT const*> (&bytes);
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// Tests whether an iterator falls within a given view.
|
|
template <typename IteratorT>
|
|
constexpr bool
|
|
intersects (view<IteratorT> a, IteratorT b)
|
|
{
|
|
return b >= a.begin () && b < a.end ();
|
|
}
|
|
|
|
|
|
///------------------------------------------------------------------------
|
|
/// Tests whether view `a` inclusively contains view `b`.
|
|
template <typename IteratorA, typename IteratorB>
|
|
constexpr bool
|
|
covers (
|
|
view<IteratorA,IteratorB> const &a,
|
|
view<IteratorA,IteratorB> const &b
|
|
) {
|
|
return a.begin () <= b.begin () && a.end () >= b.end ();
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <
|
|
typename BeginA, typename EndA,
|
|
typename BeginB, typename EndB
|
|
>
|
|
constexpr bool
|
|
equal (const view<BeginA,EndA> &a, const view<BeginB,EndB> &b)
|
|
{
|
|
return a.size () == b.size () &&
|
|
std::equal (std::begin (a), std::end (a), std::begin (b));
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
// defer equality to the view/view operator by way of make_view
|
|
template <
|
|
typename IteratorA,
|
|
typename IteratorB,
|
|
typename ValueT,
|
|
typename = std::enable_if_t<
|
|
!std::is_same_v<ValueT, view<IteratorA,IteratorB>>,
|
|
void
|
|
>
|
|
>
|
|
constexpr bool
|
|
equal (const view<IteratorA,IteratorB> &a, const ValueT &b)
|
|
{
|
|
return equal (a, make_view (b));
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
// reverse the arguments and forward to the above operator. we formumlate
|
|
// equality this way to avoid implementing the operator twice for each
|
|
// weird case.
|
|
template <
|
|
typename IteratorA,
|
|
typename IteratorB,
|
|
typename ValueT,
|
|
typename = std::enable_if_t<
|
|
!std::is_same_v<ValueT, view<IteratorA,IteratorB>>,
|
|
void
|
|
>
|
|
>
|
|
constexpr bool
|
|
equal (const ValueT &a, const view<IteratorA,IteratorB> &b)
|
|
{
|
|
return equal (b, a);
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename IteratorA, typename IteratorB>
|
|
constexpr bool
|
|
operator== (const view<IteratorA,IteratorB> &a, const view<IteratorA,IteratorB> &b)
|
|
{
|
|
return a.begin () == b.begin () && a.end () == b.end ();
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <typename IteratorA, typename IteratorB>
|
|
constexpr bool
|
|
operator!= (const view<IteratorA,IteratorB> &a, const view<IteratorA,IteratorB> &b)
|
|
{
|
|
return !(a == b);
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <
|
|
typename IteratorA,
|
|
typename IteratorB,
|
|
typename ValueT,
|
|
typename = std::enable_if_t<
|
|
!std::is_same_v<ValueT, view<IteratorA,IteratorB>>,
|
|
void
|
|
>
|
|
>
|
|
constexpr bool
|
|
operator!= (const view<IteratorA,IteratorB> &a, const ValueT &b)
|
|
{
|
|
return !(a == b);
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
template <
|
|
typename IteratorA,
|
|
typename IteratorB,
|
|
typename ValueT,
|
|
typename = std::enable_if_t<
|
|
!std::is_same_v<ValueT, view<IteratorA,IteratorB>>,
|
|
void
|
|
>
|
|
>
|
|
constexpr bool
|
|
operator!= (const ValueT &a, const view<IteratorA,IteratorB> &b)
|
|
{
|
|
return !(a == b);
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename CharT>
|
|
bool
|
|
operator== (
|
|
view<const CharT*> lhs,
|
|
const std::basic_string<CharT> &rhs
|
|
) {
|
|
return lhs.size () == rhs.size () && std::equal (lhs.cbegin (), lhs.cend (), rhs.cbegin ());
|
|
}
|
|
|
|
|
|
inline bool
|
|
operator== (view<const char*> lhs, const char *rhs)
|
|
{
|
|
return lhs.size () == strlen (rhs) && std::equal (lhs.cbegin (), lhs.cend (), rhs);
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename BeginT, typename EndT>
|
|
std::ostream&
|
|
operator<< (std::ostream &os, view<BeginT, EndT> val)
|
|
{
|
|
std::copy (
|
|
std::cbegin (val),
|
|
std::cend (val),
|
|
std::ostream_iterator<typename decltype(val)::value_type> (os)
|
|
);
|
|
|
|
return os;
|
|
}
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// a basic stringlike comparison operator that behaves as
|
|
/// std::string::compare would.
|
|
///
|
|
/// provided so that the common case of stringlike views can be used in a
|
|
/// std::map and similar without a great deal of work.
|
|
inline bool
|
|
operator< (view<const char*> a, view<const char*> b)
|
|
{
|
|
const auto la = std::size (a);
|
|
const auto lb = std::size (b);
|
|
|
|
const auto res = strncmp (
|
|
std::data (a),
|
|
std::data (b),
|
|
min (la, lb)
|
|
);
|
|
|
|
return res < 0 || (res == 0 && la < lb);
|
|
}
|
|
|
|
|
|
}
|
|
|
|
|
|
#endif
|