libcruft-util/view.hpp

392 lines
12 KiB
C++
Raw Normal View History

/*
2015-04-13 18:05:28 +10:00
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
2015-04-13 18:05:28 +10:00
* http://www.apache.org/licenses/LICENSE-2.0
*
2015-04-13 18:05:28 +10:00
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2015-2017 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_VIEW_HPP
#define CRUFT_UTIL_VIEW_HPP
2017-11-23 17:24:11 +11:00
#include "cast.hpp"
#include "debug.hpp"
#include "types/traits.hpp"
#include <cstdlib>
#include <ostream>
#include <string>
#include <cstring>
2017-08-31 13:03:19 +10:00
#include <stdexcept>
namespace util {
2017-09-15 15:22:51 +10:00
template <typename IteratorT>
struct view {
public:
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
using value_type = typename std::iterator_traits<
remove_restrict_t<IteratorT>
>::value_type;
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
constexpr
2017-09-15 15:22:51 +10:00
view (const IteratorT &first, const IteratorT &last) noexcept:
m_begin (first),
m_end (last)
{ ; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
2017-09-14 13:13:45 +10:00
constexpr
view (const view &rhs) noexcept:
view (rhs.m_begin, rhs.m_end)
2017-09-14 13:13:45 +10:00
{ ; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
2017-09-14 13:13:45 +10:00
// technically we could get away without explicitly defining a move
// constructor here, but by nulling rhs we can more easily use this
2017-12-19 18:13:03 +11:00
// class as a base for unique owning pointers without exposing the
// begin/end data members to them directly.
2017-09-14 13:13:45 +10:00
constexpr view (view &&rhs) noexcept:
view (std::move (rhs.m_begin), std::move (rhs.m_end))
{ ; }
2017-09-14 13:13:45 +10:00
2017-12-19 18:13:03 +11:00
//---------------------------------------------------------------------
// allow null construction of views where IteratorT is constructible
// from nullptr_t
//
// ideally we would avoid exposing this as it promotes use of nulls but
// it simplifies construction of views that are data members of classes
// when we may not immediately know the values we should contain.
constexpr view (std::nullptr_t) noexcept:
view {nullptr,nullptr}
{ ; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
template <typename ContainerT>
constexpr explicit
2017-09-15 15:22:51 +10:00
view (ContainerT &klass):
view (std::begin (klass), std::end (klass))
{ ; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
template <typename ContainerT>
constexpr explicit
2017-09-15 15:22:51 +10:00
view (const ContainerT &klass):
view (std::begin (klass), std::end (klass))
{ ; }
2017-09-14 13:13:45 +10:00
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
2017-09-14 13:13:45 +10:00
view&
operator= (const view &rhs) noexcept
{
m_begin = rhs.m_begin;
m_end = rhs.m_end;
return *this;
}
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
2017-09-14 13:13:45 +10:00
view&
operator= (view &&rhs) noexcept
{
m_begin = rhs.m_begin;
m_end = rhs.m_end;
2017-09-15 15:22:51 +10:00
rhs.m_begin = IteratorT{};
rhs.m_end = IteratorT{};
2017-09-14 13:13:45 +10:00
return *this;
};
2017-10-02 14:14:55 +11:00
///////////////////////////////////////////////////////////////////////
2017-09-15 15:22:51 +10:00
constexpr IteratorT begin (void) noexcept { return m_begin; }
constexpr IteratorT end (void) noexcept { return m_end; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
constexpr const IteratorT begin (void) const noexcept { return cbegin (); }
constexpr const IteratorT end (void) const noexcept { return cend (); }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
constexpr const IteratorT cbegin (void) const noexcept { return m_begin; }
constexpr const IteratorT cend (void) const noexcept { return m_end; }
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
auto data (void) { return begin (); }
auto data (void) const { return begin (); }
2017-10-02 14:14:55 +11:00
///////////////////////////////////////////////////////////////////////
constexpr bool
empty (void) const noexcept
{
return m_begin == m_end;
}
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
constexpr auto
size (void) const noexcept
{
2017-11-23 17:24:11 +11:00
return sign_cast<std::size_t> (std::distance (m_begin, m_end));
}
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
2017-08-31 13:03:19 +10:00
constexpr auto
redim (int count) const
2017-08-31 13:03:19 +10:00
{
CHECK_GT (count, 0);
2017-08-31 13:03:19 +10:00
if (count > size ())
throw std::invalid_argument ("redim to higher size not allowed");
return view { m_begin, m_begin + count };
};
2017-10-02 14:14:55 +11:00
///////////////////////////////////////////////////////////////////////
constexpr value_type&
2017-09-15 15:22:51 +10:00
operator[] (size_t idx)& noexcept
{
auto it = begin ();
std::advance (it, idx);
return *it;
}
2017-09-15 15:22:51 +10:00
//---------------------------------------------------------------------
constexpr const value_type&
2017-09-15 15:22:51 +10:00
operator[] (size_t idx) const& noexcept
{
auto it = begin ();
std::advance (it, idx);
return *it;
}
2015-02-11 16:42:32 +11:00
private:
2017-10-02 14:14:55 +11:00
///////////////////////////////////////////////////////////////////////
2017-09-15 15:22:51 +10:00
IteratorT m_begin;
IteratorT m_end;
};
2017-09-15 15:22:51 +10:00
///////////////////////////////////////////////////////////////////////////
template <typename ValueT, size_t N>
auto
2017-09-15 15:22:51 +10:00
make_view (const ValueT (&arr)[N])
{
2017-09-15 15:22:51 +10:00
return util::view<const ValueT*> (arr + 0, arr + N);
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename ContainerT>
auto
2017-09-15 15:22:51 +10:00
make_view (ContainerT &t)
{
return util::view<decltype(std::begin (t))> { std::begin (t), std::end (t) };
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename ContainerT>
auto
2017-09-15 15:22:51 +10:00
make_view (const ContainerT &t)
{
return util::view<decltype(std::cbegin (t))> { std::cbegin (t), std::cend (t) };
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
// disable the possibility of creating a view to a temporary. note that
// this only works if an lval version has already been defined otherwise
// universal reference rules will capture both lval and rval here.
template <typename ContainerT>
auto
2017-09-15 15:22:51 +10:00
make_view (ContainerT&&) = delete;
2017-09-15 15:22:51 +10:00
///////////////////////////////////////////////////////////////////////////
template <typename ContainerT>
2016-12-06 15:18:49 +11:00
auto
2017-09-15 15:22:51 +10:00
make_cview (const ContainerT &t)
{
return util::view<decltype(std::cbegin (t))> { std::cbegin (t), std::cend (t) };
}
2016-12-06 15:18:49 +11:00
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename IteratorT>
2017-02-21 21:20:15 +11:00
auto
2017-09-15 15:22:51 +10:00
make_view (IteratorT first, IteratorT last)
2017-02-21 21:20:15 +11:00
{
2017-09-15 15:22:51 +10:00
return view<IteratorT> {first, last};
2017-02-21 21:20:15 +11:00
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename ValueT>
auto
2017-09-15 15:22:51 +10:00
make_cview (ValueT *first, ValueT *last)
{
2017-09-15 15:22:51 +10:00
return view<const ValueT*> {first, last};
}
2017-09-15 15:22:51 +10:00
///////////////////////////////////////////////////////////////////////////
inline
view<const char*> make_view (const char *str)
{
return { str, str + strlen (str) };
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
inline
view<char*> make_view (char *str)
{
return { str, str + strlen (str) };
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
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)
};
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
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)
};
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename CharT, typename TraitsT, typename AllocT>
view<const CharT*>
make_view (const std::basic_string<CharT,TraitsT,AllocT>&&) = delete;
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
template <typename CharT, typename TraitsT, typename AllocT>
view<CharT*>
make_view (std::basic_string<CharT,TraitsT,AllocT>&&) = delete;
2017-02-20 18:10:26 +11:00
2017-09-15 15:22:51 +10:00
///////////////////////////////////////////////////////////////////////////
template <typename IteratorT>
constexpr bool
operator== (const view<IteratorT> &a, const view<IteratorT> &b)
{
return std::cbegin (a) == std::cbegin (b) &&
std::cend (a) == std::cend (b);
}
//-------------------------------------------------------------------------
template <typename IteratorT>
constexpr bool
operator!= (const view<IteratorT> &a, const view<IteratorT> &b)
{
return !(a == b);
}
//-------------------------------------------------------------------------
template <typename IteratorT, typename ContainerT>
constexpr bool
operator== (const ContainerT &a, const view<IteratorT> &b)
{
return make_view (a) == b;
}
//-------------------------------------------------------------------------
template <typename IteratorT, typename ContainerT>
constexpr bool
operator!= (const ContainerT &b, const view<IteratorT> &a)
{
return !(a == b);
}
//-------------------------------------------------------------------------
template <typename IteratorT, typename ContainerT>
constexpr bool
operator== (const view<IteratorT> &a, const ContainerT &b)
{
return a == make_view (b);
}
//-------------------------------------------------------------------------
template <typename IteratorT, typename ContainerT>
constexpr bool
operator!= (const view<IteratorT> &a, const ContainerT &b)
{
return !(a == b);
}
2017-12-19 18:13:49 +11:00
///////////////////////////////////////////////////////////////////////////
/// 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< (util::view<const char*> a, util::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),
util::min (la, lb)
);
return res < 0 || la < lb;
}
2017-09-15 15:22:51 +10:00
//-------------------------------------------------------------------------
// equality operations for string-like views against std::strings
bool equal (const std::string&, view<const char*>);
bool equal (const std::string&, view<char*>);
bool equal (const std::string&, view<std::string::const_iterator>);
bool equal (const std::string&, view<std::string::iterator>);
bool equal (view<const char*>, const std::string&);
bool equal (view<char*>, const std::string&);
bool equal (view<std::string::const_iterator>, const std::string&);
bool equal (view<std::string::iterator>, const std::string&);
2017-09-15 15:22:51 +10:00
///////////////////////////////////////////////////////////////////////////
template <typename IteratorT>
2016-02-10 13:07:03 +11:00
std::ostream&
2017-09-15 15:22:51 +10:00
operator<< (std::ostream&, view<IteratorT>);
}
#endif