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construct/include/ircd/vector_view.h

176 lines
4.5 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_VECTOR_VIEW_H
namespace ircd
{
template<class T> struct vector_view;
template<class T> bool empty(const vector_view<T> &) noexcept;
template<class T> size_t size(const vector_view<T> &) noexcept;
template<class T> T *data(const vector_view<T> &) noexcept;
}
/// Template to represent a contiguous vector or array in a generic way.
template<class T>
struct ircd::vector_view
{
using value_type = T;
using pointer = value_type *;
using reference = value_type &;
using difference_type = size_t;
using iterator = value_type *;
using const_iterator = const value_type *;
pointer _data { nullptr };
pointer _stop { nullptr };
public:
constexpr pointer data() const noexcept { return _data; }
constexpr size_t size() const noexcept { return std::distance(_data, _stop); }
constexpr bool empty() const noexcept { return !size(); }
const_iterator begin() const noexcept { return data(); }
const_iterator end() const noexcept { return _stop; }
const_iterator cbegin() noexcept { return data(); }
const_iterator cend() noexcept { return _stop; }
iterator begin() noexcept { return data(); }
iterator end() noexcept { return _stop; }
// Bounds check in debug only.
reference operator[](const size_t &pos) const noexcept
{
assert(pos < size());
return *(data() + pos);
}
// Bounds check at runtime.
reference at(const size_t &pos) const
{
if(unlikely(pos >= size()))
throw std::out_of_range
{
"vector_view::range_check"
};
return operator[](pos);
}
reference back() const
{
return at(size() - 1);
}
reference front() const
{
return at(0);
}
constexpr
vector_view(const pointer __restrict__ start, const pointer __restrict__ stop)
noexcept
:_data{start}
,_stop{stop}
{}
constexpr
vector_view(const pointer __restrict__ start, const size_t size)
noexcept
:vector_view(start, start + size)
{}
constexpr
vector_view(const vector_view<value_type> &start, const size_t &size)
noexcept
:vector_view(start.data(), std::min(start.size(), size))
{}
constexpr
vector_view(const std::initializer_list<value_type> &list)
noexcept
:vector_view(std::begin(list), std::end(list))
{}
template<class U,
class A>
vector_view(const std::vector<U, A> &v)
noexcept
:vector_view(v.data(), v.size())
{}
template<class U,
class A>
vector_view(std::vector<U, A> &v)
noexcept
:vector_view(v.data(), v.size())
{}
template<size_t SIZE>
constexpr
vector_view(value_type (&__restrict__ buffer)[SIZE])
noexcept
:vector_view(buffer, SIZE)
{}
template<class U,
size_t SIZE>
constexpr
vector_view(const std::array<U, SIZE> &array)
noexcept
:vector_view(const_cast<pointer>(array.data()), array.size())
{}
template<size_t SIZE>
constexpr
vector_view(std::array<value_type, SIZE> &array)
noexcept
:vector_view(array.data(), array.size())
{}
// Required for reasonable implicit const conversion of value_type.
constexpr
vector_view(const vector_view<typename std::remove_const<value_type>::type> &v)
noexcept
:vector_view(v.data(), v.size())
{}
vector_view() noexcept = default;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-copy"
vector_view &operator=(const vector_view &) noexcept = default;
#pragma GCC diagnostic pop
};
template<class T>
inline T *
ircd::data(const vector_view<T> &v)
noexcept
{
return v.data();
}
template<class T>
inline size_t
ircd::size(const vector_view<T> &v)
noexcept
{
return v.size();
}
template<class T>
inline bool
ircd::empty(const vector_view<T> &v)
noexcept
{
return v.empty();
}