libcruft-util/coord/base.hpp

237 lines
7.7 KiB
C++

/*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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 2012-2017 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_COORD_BASE_HPP
#define CRUFT_UTIL_COORD_BASE_HPP
#include "fwd.hpp"
#include "ops.hpp"
#include "init.hpp"
#include "traits.hpp"
#include "../maths.hpp"
#include <algorithm>
#include <cstdlib>
#include <type_traits>
namespace util::coord {
/////////////////////////////////////////////////////////////////////////
// the base class for all coordinate-like types.
//
// SelfT should not be exposed as a template template directly because
// some types (eg, XYZ colours) do not conform to the same template
// parameters are others (eg, vector2f). ie, it does not make sense to
// allow redim, or type changing on some types so they just aren't exposed.
template <
std::size_t S,
typename T,
typename SelfT
>
struct base : public init<S,T,SelfT> {
static_assert (S > 0);
static_assert (std::is_arithmetic<T>::value);
static_assert (sizeof (init<S,T,SelfT>) == S * sizeof (T));
using value_type = T;
static constexpr std::size_t dimension = S;
static constexpr std::size_t elements = S;
/// returns the number of elements we contain
static constexpr auto size (void) { return S; }
// constructors
using init<S,T,SelfT>::init;
/// constructs, but does not initialise, the data.
///
/// used to avoid unnecessary initialisation in many situations where
/// we have arrays of these types that are about to be overwritten. it
/// is a very important performance optimisation.
base () = default;
/// constructs an instance where all elements are initialised to `val'.
constexpr explicit
base (T fill)
{
for (decltype(S) i = 0; i < S; ++i)
this->data[i] = fill;
}
constexpr base (const base<S,T,SelfT> &rhs) = default;
base& operator= (const base<S,T,SelfT> &rhs)& = default;
base& operator= (const T t)&
{
for (auto v: *this)
v = t;
return *this;
}
// element accessors
constexpr T& operator[] (size_t i)& noexcept { return this->data[i]; }
constexpr T& operator[] (int i)& noexcept { return this->data[i]; }
constexpr const T& operator[] (size_t i) const& noexcept { return this->data[i]; }
constexpr const T& operator[] (int i) const& noexcept { return this->data[i]; }
auto cbegin (void) const { return std::cbegin (this->data); }
auto cend (void) const { return std::cend (this->data); }
auto begin (void) const { return std::begin (this->data); }
auto end (void) const { return std::end (this->data); }
auto begin (void) { return std::begin (this->data); }
auto end (void) { return std::end (this->data); }
const T& front (void) const { return this->data[0]; }
T& front (void) { return this->data[0]; }
const T& back (void) const { return this->data[S-1]; }
T& back (void) { return this->data[S-1]; }
///////////////////////////////////////////////////////////////////////
// conversions
template <template <std::size_t, typename> class K>
K<S,T> as (void) const
{
K<S,T> k;
std::copy (begin (), end (), k.begin ());
return k;
}
//---------------------------------------------------------------------
template <
typename K,
typename = std::enable_if_t<is_coord_v<K>,void>
>
K as (void) const
{
static_assert (K::elements == elements);
K k;
std::copy (begin (), end (), k.begin ());
return k;
}
//---------------------------------
template <typename U>
auto
cast (void) const
{
typename revalue_type<SelfT>::template type<U> out;
std::copy (std::cbegin (this->data),
std::cend (this->data),
std::begin (out.data));
return out;
}
///////////////////////////////////////////////////////////////////////
/// returns an instance with the same data, but truncated to `D'
/// elements
///
/// explicitly does not allow a fill parameter given it can't be used
/// when reducing dimensions.
template <
size_t D,
typename _sfinae = SelfT
>
std::enable_if_t<
has_redim_v<_sfinae>,
redim_t<_sfinae,D>
>
redim (void) const
{
redim_t<SelfT,D> out;
std::copy_n (std::cbegin (this->data),
min (S, D),
std::begin (out.data));
return out;
}
//---------------------------------------------------------------------
/// returns an instance with the same data, but more elements, where
/// the new elements are initialised with values with the same index
/// in the coordinate `fill'.
///
/// explicitly requires a fill parameter so that we avoid undefined
/// values.
template<size_t D,typename _sfinae = SelfT>
std::enable_if_t<
has_redim_v<_sfinae>,
redim_t<_sfinae,D>
>
redim (const redim_t<_sfinae,D> fill) const
{
redim_t<SelfT,D> out;
auto next = std::copy (cbegin (), cend (), std::begin (out));
std::copy (std::cbegin (fill) + S, std::cend (fill), next);
return out;
}
//---------------------------------------------------------------------
/// returns an instance with the same data, but more elements, where
/// all the new elemenst are initialised with the scalar `fill'.
///
/// explicitly requires a fill parameter so that we avoid undefined
/// values.
template <
size_t D,
typename _sfinae = SelfT
>
std::enable_if_t<
has_redim_v<_sfinae>,
redim_t<_sfinae,D>
>
redim (T fill) const
{
redim_t<SelfT,D> out;
auto next = std::copy (cbegin (), cend (), std::begin (out));
std::fill (next, std::end (out), fill);
return out;
}
///////////////////////////////////////////////////////////////////////
/// returns an instance with elements specified by the Indices
/// parameter. eg, point2f p{}.indices<0,2> would return {p.x, p.z}.
///
/// it's ugly as sin, but simplifies some situations where we don't
/// want a temporary.
template <std::size_t ...Indices>
constexpr auto
indices (void) const
{
static_assert (
all (make_vector ((Indices < S)...)),
"indices must fall within the defined range for the type"
);
return redim_t<SelfT,sizeof...(Indices)> {
this->data[Indices]...
};
}
};
}
#endif