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rAKA akantu
aka_iterators.hh
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/**
* @file aka_iterators.hh
*
* @author Nicolas Richart <nicolas.richart@epfl.ch>
*
* @date creation: Fri Aug 11 2017
* @date last modification: Mon Jan 29 2018
*
* @brief iterator interfaces
*
* @section LICENSE
*
* Copyright (©) 2016-2018 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* Akantu is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* Akantu is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include "aka_compatibilty_with_cpp_standard.hh"
/* -------------------------------------------------------------------------- */
#include <tuple>
#include <utility>
/* -------------------------------------------------------------------------- */
#ifndef __AKANTU_AKA_ITERATORS_HH__
#define __AKANTU_AKA_ITERATORS_HH__
namespace
akantu
{
namespace
tuple
{
/* ------------------------------------------------------------------------ */
namespace
details
{
template
<
size_t
N
>
struct
Foreach
{
template
<
class
Tuple
>
static
inline
bool
not_equal
(
Tuple
&&
a
,
Tuple
&&
b
)
{
if
(
std
::
get
<
N
-
1
>
(
std
::
forward
<
Tuple
>
(
a
))
==
std
::
get
<
N
-
1
>
(
std
::
forward
<
Tuple
>
(
b
)))
return
false
;
return
Foreach
<
N
-
1
>::
not_equal
(
std
::
forward
<
Tuple
>
(
a
),
std
::
forward
<
Tuple
>
(
b
));
}
};
/* ---------------------------------------------------------------------- */
template
<>
struct
Foreach
<
0
>
{
template
<
class
Tuple
>
static
inline
bool
not_equal
(
Tuple
&&
a
,
Tuple
&&
b
)
{
return
std
::
get
<
0
>
(
std
::
forward
<
Tuple
>
(
a
))
!=
std
::
get
<
0
>
(
std
::
forward
<
Tuple
>
(
b
));
}
};
template
<
typename
...
Ts
>
decltype
(
auto
)
make_tuple_no_decay
(
Ts
&&
...
args
)
{
return
std
::
tuple
<
Ts
...
>
(
std
::
forward
<
Ts
>
(
args
)...);
}
template
<
class
F
,
class
Tuple
,
size_t
...
Is
>
void
foreach_impl
(
F
&&
func
,
Tuple
&&
tuple
,
std
::
index_sequence
<
Is
...
>
&&
)
{
(
void
)
std
::
initializer_list
<
int
>
{
(
std
::
forward
<
F
>
(
func
)(
std
::
get
<
Is
>
(
std
::
forward
<
Tuple
>
(
tuple
))),
0
)...};
}
template
<
class
F
,
class
Tuple
,
size_t
...
Is
>
decltype
(
auto
)
transform_impl
(
F
&&
func
,
Tuple
&&
tuple
,
std
::
index_sequence
<
Is
...
>
&&
)
{
return
make_tuple_no_decay
(
std
::
forward
<
F
>
(
func
)(
std
::
get
<
Is
>
(
std
::
forward
<
Tuple
>
(
tuple
)))...);
}
}
// namespace details
/* ------------------------------------------------------------------------ */
template
<
class
Tuple
>
bool
are_not_equal
(
Tuple
&&
a
,
Tuple
&&
b
)
{
return
details
::
Foreach
<
std
::
tuple_size
<
std
::
decay_t
<
Tuple
>>::
value
>::
not_equal
(
std
::
forward
<
Tuple
>
(
a
),
std
::
forward
<
Tuple
>
(
b
));
}
template
<
class
F
,
class
Tuple
>
void
foreach
(
F
&&
func
,
Tuple
&&
tuple
)
{
return
details
::
foreach_impl
(
std
::
forward
<
F
>
(
func
),
std
::
forward
<
Tuple
>
(
tuple
),
std
::
make_index_sequence
<
std
::
tuple_size
<
std
::
decay_t
<
Tuple
>>::
value
>
{});
}
template
<
class
F
,
class
Tuple
>
decltype
(
auto
)
transform
(
F
&&
func
,
Tuple
&&
tuple
)
{
return
details
::
transform_impl
(
std
::
forward
<
F
>
(
func
),
std
::
forward
<
Tuple
>
(
tuple
),
std
::
make_index_sequence
<
std
::
tuple_size
<
std
::
decay_t
<
Tuple
>>::
value
>
{});
}
}
// namespace tuple
/* -------------------------------------------------------------------------- */
namespace
iterators
{
namespace
{
template
<
typename
It
,
typename
category
>
struct
is_at_least_category
:
std
::
is_same
<
std
::
common_type_t
<
typename
std
::
iterator_traits
<
It
>::
iterator_category
,
category
>
,
category
>
{};
}
// namespace
template
<
class
...
Iterators
>
class
ZipIterator
{
public
:
using
value_type
=
std
::
tuple
<
typename
std
::
iterator_traits
<
Iterators
>::
value_type
...
>
;
using
difference_type
=
std
::
common_type_t
<
typename
std
::
iterator_traits
<
Iterators
>::
difference_type
...
>
;
using
pointer
=
std
::
tuple
<
typename
std
::
iterator_traits
<
Iterators
>::
pointer
...
>
;
using
reference
=
std
::
tuple
<
typename
std
::
iterator_traits
<
Iterators
>::
reference
...
>
;
using
iterator_category
=
std
::
input_iterator_tag
;
// std::common_type_t<typename
// std::iterator_traits<Iterators>::iterator_category...>;
private
:
using
tuple_t
=
std
::
tuple
<
Iterators
...
>
;
public
:
explicit
ZipIterator
(
tuple_t
iterators
)
:
iterators
(
std
::
move
(
iterators
))
{}
// input iterator ++it
ZipIterator
&
operator
++
()
{
tuple
::
foreach
([](
auto
&&
it
)
{
++
it
;
},
iterators
);
return
*
this
;
}
// input iterator it++
ZipIterator
operator
++
(
int
)
{
auto
cpy
=
*
this
;
tuple
::
foreach
([](
auto
&&
it
)
{
++
it
;
},
iterators
);
return
cpy
;
}
// input iterator it != other_it
bool
operator
!=
(
const
ZipIterator
&
other
)
const
{
return
tuple
::
are_not_equal
(
iterators
,
other
.
iterators
);
}
// input iterator dereference *it
decltype
(
auto
)
operator
*
()
{
return
tuple
::
transform
([](
auto
&&
it
)
->
decltype
(
auto
)
{
return
*
it
;
},
iterators
);
}
bool
operator
==
(
const
ZipIterator
&
other
)
const
{
return
not
tuple
::
are_not_equal
(
iterators
,
other
.
iterators
);
}
private
:
tuple_t
iterators
;
};
}
// namespace iterators
/* -------------------------------------------------------------------------- */
template
<
class
...
Iterators
>
decltype
(
auto
)
zip_iterator
(
std
::
tuple
<
Iterators
...
>
&&
iterators_tuple
)
{
auto
zip
=
iterators
::
ZipIterator
<
Iterators
...
>
(
std
::
forward
<
decltype
(
iterators_tuple
)
>
(
iterators_tuple
));
return
zip
;
}
/* -------------------------------------------------------------------------- */
namespace
containers
{
template
<
class
...
Containers
>
class
ZipContainer
{
using
containers_t
=
std
::
tuple
<
Containers
...
>
;
public
:
explicit
ZipContainer
(
Containers
&&
...
containers
)
:
containers
(
std
::
forward
<
Containers
>
(
containers
)...)
{}
decltype
(
auto
)
begin
()
const
{
return
zip_iterator
(
tuple
::
transform
([](
auto
&&
c
)
{
return
c
.
begin
();
},
std
::
forward
<
containers_t
>
(
containers
)));
}
decltype
(
auto
)
end
()
const
{
return
zip_iterator
(
tuple
::
transform
([](
auto
&&
c
)
{
return
c
.
end
();
},
std
::
forward
<
containers_t
>
(
containers
)));
}
decltype
(
auto
)
begin
()
{
return
zip_iterator
(
tuple
::
transform
([](
auto
&&
c
)
{
return
c
.
begin
();
},
std
::
forward
<
containers_t
>
(
containers
)));
}
decltype
(
auto
)
end
()
{
return
zip_iterator
(
tuple
::
transform
([](
auto
&&
c
)
{
return
c
.
end
();
},
std
::
forward
<
containers_t
>
(
containers
)));
}
private
:
containers_t
containers
;
};
template
<
class
Iterator
>
class
Range
{
public
:
explicit
Range
(
Iterator
&&
it1
,
Iterator
&&
it2
)
:
iterators
(
std
::
forward
<
Iterator
>
(
it1
),
std
::
forward
<
Iterator
>
(
it2
))
{}
decltype
(
auto
)
begin
()
const
{
return
std
::
get
<
0
>
(
iterators
);
}
decltype
(
auto
)
begin
()
{
return
std
::
get
<
0
>
(
iterators
);
}
decltype
(
auto
)
end
()
const
{
return
std
::
get
<
1
>
(
iterators
);
}
decltype
(
auto
)
end
()
{
return
std
::
get
<
1
>
(
iterators
);
}
private
:
std
::
tuple
<
Iterator
,
Iterator
>
iterators
;
};
}
// namespace containers
/* -------------------------------------------------------------------------- */
template
<
class
...
Containers
>
decltype
(
auto
)
zip
(
Containers
&&
...
conts
)
{
return
containers
::
ZipContainer
<
Containers
...
>
(
std
::
forward
<
Containers
>
(
conts
)...);
}
template
<
class
Iterator
>
decltype
(
auto
)
range
(
Iterator
&&
it1
,
Iterator
&&
it2
)
{
return
containers
::
Range
<
Iterator
>
(
std
::
forward
<
Iterator
>
(
it1
),
std
::
forward
<
Iterator
>
(
it2
));
}
/* -------------------------------------------------------------------------- */
/* Arange */
/* -------------------------------------------------------------------------- */
namespace
iterators
{
template
<
class
T
>
class
ArangeIterator
{
public
:
using
value_type
=
T
;
using
pointer
=
T
*
;
using
reference
=
T
&
;
using
difference_type
=
size_t
;
using
iterator_category
=
std
::
input_iterator_tag
;
constexpr
ArangeIterator
(
T
value
,
T
step
)
:
value
(
value
),
step
(
step
)
{}
constexpr
ArangeIterator
(
const
ArangeIterator
&
)
=
default
;
constexpr
ArangeIterator
&
operator
++
()
{
value
+=
step
;
return
*
this
;
}
constexpr
T
operator
*
()
const
{
return
value
;
}
constexpr
bool
operator
==
(
const
ArangeIterator
&
other
)
const
{
return
(
value
==
other
.
value
)
and
(
step
==
other
.
step
);
}
constexpr
bool
operator
!=
(
const
ArangeIterator
&
other
)
const
{
return
not
operator
==
(
other
);
}
private
:
T
value
{
0
};
const
T
step
{
1
};
};
}
// namespace iterators
namespace
containers
{
template
<
class
T
>
class
ArangeContainer
{
public
:
using
iterator
=
iterators
::
ArangeIterator
<
T
>
;
using
const_iterator
=
iterators
::
ArangeIterator
<
T
>
;
constexpr
ArangeContainer
(
T
start
,
T
stop
,
T
step
=
1
)
:
start
(
start
),
stop
((
stop
-
start
)
%
step
==
0
?
stop
:
start
+
(
1
+
(
stop
-
start
)
/
step
)
*
step
),
step
(
step
)
{}
explicit
constexpr
ArangeContainer
(
T
stop
)
:
ArangeContainer
(
0
,
stop
,
1
)
{}
constexpr
T
operator
[](
size_t
i
)
{
T
val
=
start
+
i
*
step
;
assert
(
val
<
stop
&&
"i is out of range"
);
return
val
;
}
constexpr
T
size
()
{
return
(
stop
-
start
)
/
step
;
}
constexpr
iterator
begin
()
{
return
iterator
(
start
,
step
);
}
constexpr
iterator
end
()
{
return
iterator
(
stop
,
step
);
}
private
:
const
T
start
{
0
},
stop
{
0
},
step
{
1
};
};
}
// namespace containers
template
<
class
T
,
typename
=
std
::
enable_if_t
<
std
::
is_integral
<
std
::
decay_t
<
T
>>::
value
>>
inline
decltype
(
auto
)
arange
(
const
T
&
stop
)
{
return
containers
::
ArangeContainer
<
T
>
(
stop
);
}
template
<
class
T1
,
class
T2
,
typename
=
std
::
enable_if_t
<
std
::
is_integral
<
std
::
common_type_t
<
T1
,
T2
>>::
value
>>
inline
constexpr
decltype
(
auto
)
arange
(
const
T1
&
start
,
const
T2
&
stop
)
{
return
containers
::
ArangeContainer
<
std
::
common_type_t
<
T1
,
T2
>>
(
start
,
stop
);
}
template
<
class
T1
,
class
T2
,
class
T3
,
typename
=
std
::
enable_if_t
<
std
::
is_integral
<
std
::
common_type_t
<
T1
,
T2
,
T3
>>::
value
>>
inline
constexpr
decltype
(
auto
)
arange
(
const
T1
&
start
,
const
T2
&
stop
,
const
T3
&
step
)
{
return
containers
::
ArangeContainer
<
std
::
common_type_t
<
T1
,
T2
,
T3
>>
(
start
,
stop
,
step
);
}
/* -------------------------------------------------------------------------- */
template
<
class
Container
>
inline
constexpr
decltype
(
auto
)
enumerate
(
Container
&&
container
,
size_t
start_
=
0
)
{
auto
stop
=
std
::
forward
<
Container
>
(
container
).
size
();
decltype
(
stop
)
start
=
start_
;
return
zip
(
arange
(
start
,
stop
),
std
::
forward
<
Container
>
(
container
));
}
namespace
iterators
{
template
<
class
iterator_t
,
class
operator_t
>
class
transform_adaptor_iterator
{
public
:
using
value_type
=
decltype
(
std
::
declval
<
operator_t
>
()(
std
::
declval
<
typename
iterator_t
::
value_type
>
()));
using
difference_type
=
typename
iterator_t
::
difference_type
;
using
pointer
=
std
::
decay_t
<
value_type
>
*
;
using
reference
=
value_type
&
;
using
iterator_category
=
typename
iterator_t
::
iterator_category
;
transform_adaptor_iterator
(
iterator_t
it
,
operator_t
&&
op
)
:
it
(
std
::
move
(
it
)),
op
(
op
)
{}
transform_adaptor_iterator
(
const
transform_adaptor_iterator
&
)
=
default
;
transform_adaptor_iterator
&
operator
++
()
{
++
it
;
return
*
this
;
}
decltype
(
auto
)
operator
*
()
const
{
return
op
(
*
it
);
}
bool
operator
==
(
const
transform_adaptor_iterator
&
other
)
const
{
return
(
it
==
other
.
it
);
}
bool
operator
!=
(
const
transform_adaptor_iterator
&
other
)
const
{
return
not
operator
==
(
other
);
}
private
:
iterator_t
it
;
operator_t
op
;
};
template
<
class
iterator_t
,
class
operator_t
>
decltype
(
auto
)
make_transform_adaptor_iterator
(
iterator_t
it
,
operator_t
&&
op
)
{
return
transform_adaptor_iterator
<
iterator_t
,
operator_t
>
(
it
,
std
::
forward
<
operator_t
>
(
op
));
}
}
// namespace iterators
namespace
containers
{
template
<
class
container_t
,
class
operator_t
>
class
TransformIteratorAdaptor
{
public
:
using
const_iterator
=
typename
std
::
decay_t
<
container_t
>::
const_iterator
;
using
iterator
=
typename
std
::
decay_t
<
container_t
>::
iterator
;
TransformIteratorAdaptor
(
container_t
&&
cont
,
operator_t
&&
op
)
:
cont
(
std
::
forward
<
container_t
>
(
cont
)),
op
(
std
::
forward
<
operator_t
>
(
op
))
{}
decltype
(
auto
)
begin
()
const
{
return
iterators
::
make_transform_adaptor_iterator
(
cont
.
begin
(),
op
);
}
decltype
(
auto
)
begin
()
{
return
iterators
::
make_transform_adaptor_iterator
(
cont
.
begin
(),
op
);
}
decltype
(
auto
)
end
()
const
{
return
iterators
::
make_transform_adaptor_iterator
(
cont
.
end
(),
op
);
}
decltype
(
auto
)
end
()
{
return
iterators
::
make_transform_adaptor_iterator
(
cont
.
end
(),
op
);
}
private
:
container_t
cont
;
operator_t
op
;
};
}
// namespace containers
template
<
class
container_t
,
class
operator_t
>
decltype
(
auto
)
make_transform_adaptor
(
container_t
&&
cont
,
operator_t
&&
op
)
{
return
containers
::
TransformIteratorAdaptor
<
container_t
,
operator_t
>
(
std
::
forward
<
container_t
>
(
cont
),
std
::
forward
<
operator_t
>
(
op
));
}
template
<
class
container_t
>
decltype
(
auto
)
make_keys_adaptor
(
container_t
&&
cont
)
{
return
make_transform_adaptor
(
std
::
forward
<
container_t
>
(
cont
),
[](
auto
&&
pair
)
->
decltype
(
pair
.
first
)
{
return
pair
.
first
;
});
}
template
<
class
container_t
>
decltype
(
auto
)
make_values_adaptor
(
container_t
&&
cont
)
{
return
make_transform_adaptor
(
std
::
forward
<
container_t
>
(
cont
),
[](
auto
&&
pair
)
->
decltype
(
pair
.
second
)
{
return
pair
.
second
;
});
}
template
<
class
container_t
>
decltype
(
auto
)
make_dereference_adaptor
(
container_t
&&
cont
)
{
return
make_transform_adaptor
(
std
::
forward
<
container_t
>
(
cont
),
[](
auto
&&
value
)
->
decltype
(
*
value
)
{
return
*
value
;
});
}
}
// namespace akantu
namespace
std
{
template
<
typename
...
Its
>
struct
iterator_traits
<::
akantu
::
iterators
::
ZipIterator
<
Its
...
>>
{
using
iterator_category
=
forward_iterator_tag
;
using
value_type
=
typename
::
akantu
::
iterators
::
ZipIterator
<
Its
...
>::
value_type
;
using
difference_type
=
typename
::
akantu
::
iterators
::
ZipIterator
<
Its
...
>::
difference_type
;
using
pointer
=
typename
::
akantu
::
iterators
::
ZipIterator
<
Its
...
>::
pointer
;
using
reference
=
typename
::
akantu
::
iterators
::
ZipIterator
<
Its
...
>::
reference
;
};
}
// namespace std
#endif
/* __AKANTU_AKA_ITERATORS_HH__ */
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