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rippled/beast/container/buffer_view.h
Vinnie Falco ce8f56727e Make all include paths relative to a root directory:
* Better include path support in the VSProject scons tool.
* Various manual fixes to include paths.
2014-06-02 09:16:28 -07:00

521 lines
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C++

//------------------------------------------------------------------------------
/*
This file is part of Beast: https://github.com/vinniefalco/Beast
Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
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 appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#ifndef BEAST_CONTAINER_BUFFER_VIEW_H_INCLUDED
#define BEAST_CONTAINER_BUFFER_VIEW_H_INCLUDED
#include <beast/Config.h>
#include <array>
#include <beast/cxx14/algorithm.h> // <algorithm>
#include <cstddef>
#include <iterator>
#include <memory>
#include <string>
#include <vector>
#include <beast/cxx14/type_traits.h> // <type_traits>
namespace beast {
namespace detail {
template <class T, class U,
bool = std::is_const <std::remove_reference_t <T>>::value>
struct apply_const
{
typedef U type;
};
template <class T, class U>
struct apply_const <T, U, true>
{
typedef const U type;
};
// is_contiguous is true if C is a contiguous container
template <class C>
struct is_contiguous
: public std::false_type
{
};
template <class C>
struct is_contiguous <C const>
: public is_contiguous <C>
{
};
template <class T, class Alloc>
struct is_contiguous <std::vector <T, Alloc>>
: public std::true_type
{
};
template <class CharT, class Traits, class Alloc>
struct is_contiguous <std::basic_string<
CharT, Traits, Alloc>>
: public std::true_type
{
};
template <class T, std::size_t N>
struct is_contiguous <std::array<T, N>>
: public std::true_type
{
};
// True if T is const or U is not const
template <class T, class U>
struct buffer_view_const_compatible : std::integral_constant <bool,
std::is_const<T>::value || ! std::is_const<U>::value
>
{
};
// True if T and U are the same or differ only in const, or
// if T and U are equally sized integral types.
template <class T, class U>
struct buffer_view_ptr_compatible : std::integral_constant <bool,
(std::is_same <std::remove_const <T>, std::remove_const <U>>::value) ||
(std::is_integral <T>::value && std::is_integral <U>::value &&
sizeof (U) == sizeof (T))
>
{
};
// Determine if buffer_view <T, ..> is constructible from U*
template <class T, class U>
struct buffer_view_convertible : std::integral_constant <bool,
buffer_view_const_compatible <T, U>::value &&
buffer_view_ptr_compatible <T, U>::value
>
{
};
// True if C is a container that can be used to construct a buffer_view<T>
template <class T, class C>
struct buffer_view_container_compatible : std::integral_constant <bool,
is_contiguous <C>::value && buffer_view_convertible <T,
typename apply_const <C, typename C::value_type>::type>::value
>
{
};
} // detail
struct buffer_view_default_tag
{
};
//------------------------------------------------------------------------------
/** A view into a range of contiguous container elements.
The size of the view is determined at the time of construction.
This tries to emulate the interface of std::vector as closely as possible,
with the constraint that the size of the container cannot be changed.
@tparam T The underlying element type. If T is const, member functions
which can modify elements are removed from the interface.
@tparam Tag A type used to prevent two views with the same T from being
comparable or assignable.
*/
template <
class T,
class Tag = buffer_view_default_tag
>
class buffer_view
{
private:
T* m_base;
std::size_t m_size;
static_assert (std::is_same <T, std::remove_reference_t <T>>::value,
"T may not be a reference type");
static_assert (! std::is_same <T, void>::value,
"T may not be void");
static_assert (std::is_same <std::add_const_t <T>,
std::remove_reference_t <T> const>::value,
"Expected std::add_const to produce T const");
template <class Iter>
void
assign (Iter first, Iter last) noexcept
{
typedef typename std::iterator_traits <Iter>::value_type U;
static_assert (detail::buffer_view_const_compatible <T, U>::value,
"Cannot convert from 'U const' to 'T', "
"conversion loses const qualifiers");
static_assert (detail::buffer_view_ptr_compatible <T, U>::value,
"Cannot convert from 'U*' to 'T*, "
"types are incompatible");
if (first == last)
{
m_base = nullptr;
m_size = 0;
}
else
{
#if 0
// fails on gcc
m_base = reinterpret_cast <T*> (
std::addressof (*first));
#else
m_base = reinterpret_cast <T*> (&*first);
#endif
m_size = std::distance (first, last);
}
}
public:
typedef T value_type;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
typedef T& reference;
typedef T const& const_reference;
typedef T* pointer;
typedef T const* const_pointer;
typedef T* iterator;
typedef T const* const_iterator;
typedef std::reverse_iterator <iterator> reverse_iterator;
typedef std::reverse_iterator <const_iterator> const_reverse_iterator;
// default construct
buffer_view () noexcept
: m_base (nullptr)
, m_size (0)
{
}
// copy construct
template <class U,
class = std::enable_if_t <
detail::buffer_view_convertible <T, U>::value>
>
buffer_view (buffer_view <U, Tag> v) noexcept
{
assign (v.begin(), v.end());
}
// construct from container
template <class C,
class = std::enable_if_t <
detail::buffer_view_container_compatible <T, C>::value
>
>
buffer_view (C& c) noexcept
{
assign (c.begin(), c.end());
}
// construct from pointer range
template <class U,
class = std::enable_if_t <
detail::buffer_view_convertible <T, U>::value>
>
buffer_view (U* first, U* last) noexcept
{
assign (first, last);
}
// construct from base and size
template <class U,
class = std::enable_if_t <
detail::buffer_view_convertible <T, U>::value>
>
buffer_view (U* u, std::size_t n) noexcept
: m_base (u)
, m_size (n)
{
}
// assign from container
template <class C,
class = std::enable_if_t <
detail::buffer_view_container_compatible <T, C>::value
>
>
buffer_view&
operator= (C& c) noexcept
{
assign (c.begin(), c.end());
return *this;
}
//
// Element access
//
reference
at (size_type pos)
{
if (! (pos < size()))
throw std::out_of_range ("bad array index");
return m_base [pos];
}
const_reference
at (size_type pos) const
{
if (! (pos < size()))
throw std::out_of_range ("bad array index");
return m_base [pos];
}
reference
operator[] (size_type pos) noexcept
{
return m_base [pos];
}
const_reference
operator[] (size_type pos) const noexcept
{
return m_base [pos];
}
reference
back() noexcept
{
return m_base [m_size - 1];
}
const_reference
back() const noexcept
{
return m_base [m_size - 1];
}
reference
front() noexcept
{
return *m_base;
}
const_reference
front() const noexcept
{
return *m_base;
}
pointer
data() noexcept
{
return m_base;
}
const_pointer
data() const noexcept
{
return m_base;
}
//
// Iterators
//
iterator
begin() noexcept
{
return m_base;
}
const_iterator
begin() const noexcept
{
return m_base;
}
const_iterator
cbegin() const noexcept
{
return m_base;
}
iterator
end() noexcept
{
return m_base + m_size;
}
const_iterator
end() const noexcept
{
return m_base + m_size;
}
const_iterator
cend() const noexcept
{
return m_base + m_size;
}
reverse_iterator
rbegin() noexcept
{
return reverse_iterator (end());
}
const_reverse_iterator
rbegin() const noexcept
{
return const_reverse_iterator (cend());
}
const_reverse_iterator
crbegin() const noexcept
{
return const_reverse_iterator (cend());
}
reverse_iterator
rend() noexcept
{
return reverse_iterator (begin());
}
const_reverse_iterator
rend() const noexcept
{
return const_reverse_iterator (cbegin());
}
const_reverse_iterator
crend() const noexcept
{
return const_reverse_iterator (cbegin());
}
//
// Capacity
//
bool
empty() const noexcept
{
return m_size == 0;
}
size_type
size() const noexcept
{
return m_size;
}
size_type
max_size() const noexcept
{
return size();
}
size_type
capacity() const noexcept
{
return size();
}
//
// Modifiers
//
template <class U, class K>
friend void swap (buffer_view <U, K>& lhs,
buffer_view <U, K>& rhs) noexcept;
};
//------------------------------------------------------------------------------
template <class T, class Tag>
inline
bool
operator== (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return std::equal (
lhs.cbegin(), lhs.cend(), rhs.cbegin(), rhs.cend());
}
template <class T, class Tag>
inline
bool
operator!= (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return ! (lhs == rhs);
}
template <class T, class Tag>
inline
bool
operator< (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return std::lexicographical_compare (
lhs.cbegin(), lhs.cend(), rhs.cbegin(), rhs.cend());
}
template <class T, class Tag>
inline
bool
operator>= (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return ! (lhs < rhs);
}
template <class T, class Tag>
inline
bool
operator> (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return rhs < lhs;
}
template <class T, class Tag>
inline
bool
operator<= (buffer_view <T, Tag> lhs, buffer_view <T, Tag> rhs)
{
return ! (rhs < lhs);
}
template <class T, class Tag>
inline
void
swap (buffer_view <T, Tag>& lhs, buffer_view <T, Tag>& rhs) noexcept
{
std::swap (lhs.m_base, rhs.m_base);
std::swap (lhs.m_size, rhs.m_size);
}
//------------------------------------------------------------------------------
template <
class T,
class Tag = buffer_view_default_tag
>
using const_buffer_view = buffer_view <
std::add_const_t <T>, Tag>;
}
#endif