std::ranges::set_symmetric_difference() algorithm
- od C++20
- Simplified
- Detailed
constexpr set_symmetric_difference_result<I1, I2, O>
set_symmetric_difference( I1 first1, S1 last1, I2 first2, S2 last2,
O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
// (2)
constexpr set_symmetric_difference_result<ranges::borrowed_iterator_t<R1>,
ranges::borrowed_iterator_t<R2>, O>
set_symmetric_difference( R1&& r1, R2&& r2, O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
The type of arguments are generic and have the following constraints:
I1
,I2
-std::input_iterator
S1
,S2
-std::sentinel_for<I1>
,std::sentinel_for<I2>
R1
,R2
-std::ranges::input_range
O
-std::weakly_incrementable
Comp
- (none)Proj1
,Proj2
- (none)
The Proj
and Comp
template arguments have the following default types: std::identity
, ranges::less
for all overloads.
Additionaly, each overload has the following constraints:
- (1) -
mergeable<I1, I2, O, Comp, Proj1, Proj2>
- (2) -
mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>, O, Comp, Proj1, Proj2>
(The std::
namespace was ommited here for readability)
The std::
namespace was ommited here for readability)
// (1)
template<
std::input_iterator I1,
std::sentinel_for<I1> S1,
std::input_iterator I2,
std::sentinel_for<I2> S2,
std::weakly_incrementable O,
class Comp = ranges::less,
class Proj1 = std::identity,
class Proj2 = std::identity
>
requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
constexpr set_symmetric_difference_result<I1, I2, O>
set_symmetric_difference( I1 first1, S1 last1, I2 first2, S2 last2,
O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
// (2)
template<
ranges::input_range R1,
ranges::input_range R2,
std::weakly_incrementable O,
class Comp = ranges::less,
class Proj1 = std::identity,
class Proj2 = std::identity
>
requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
O, Comp, Proj1, Proj2>
constexpr set_symmetric_difference_result<ranges::borrowed_iterator_t<R1>,
ranges::borrowed_iterator_t<R2>, O>
set_symmetric_difference( R1&& r1, R2&& r2, O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
With the helper types defined as follows:
template< class I1, class I2, class O >
using set_symmetric_difference_result = ranges::in_in_out_result<I1, I2, O>;
Computes symmetric difference of two sorted ranges, the elements that are found in either of the ranges,
but not in both of them are copied to the range beginning at result
. The resulting range is also sorted.
If some element is found m
times in [first1
; last1
) and n
times in [first2
; last2
),
it will be copied to result exactly std::abs(m - n)
times:
-
If
m > n
, then the lastm - n
of those elements are copied from [first1
;last1
) -
Otherwise, the last
n - m
elements are copied from [first2
;last2
). The resulting range cannot overlap with either of the input ranges. -
(1) Elements are compared using the given binary comparison function
comp
. -
(2) Same as (1), but uses
r1
as the first range andr2
as the second range, as if usingranges::begin(r1)
asfirst1
,ranges::end(r1)
aslast1
,ranges::begin(r2)
asfirst2
, andranges::end(r2)
aslast2
.
The behavior is undefined
if:- The input ranges are not sorted with respect to
comp
andproj1
orproj2
, respectively - Or the resulting range overlaps with either of the input ranges.
The function-like entities described on this page are niebloids.
Parameters
first1 last1 | The first sorted input range. |
r1 | The first sorted input range. |
first2 last2 | The second sorted input range. |
r2 | The second sorted input range. |
result | The beginning of the destination range. |
comp | Comparator to apply to the projected elements. |
proj1 | Projection to apply to the elements in the first range. |
proj2 | Projection to apply to the elements in the second range. |
Return value
A value of type ranges::set_symmetric_difference_result
initialized as follows:
{
last1,
last2,
result_last
}
Where result_last
is the end of the constructed range.
Complexity
Given N1
as ranges::distance(first1, last1)
and N2
as ranges::distance(first2, last12)
:
2 * (N1 + N2) − 1 comparisons and applications of each projection.
Exceptions
(none)
Possible implementation
set_symmetric_difference(1) and set_symmetric_difference(2)
struct set_symmetric_difference_fn
{
template<std::input_iterator I1, std::sentinel_for<I1> S1,
std::input_iterator I2, std::sentinel_for<I2> S2,
std::weakly_incrementable O, class Comp = ranges::less,
class Proj1 = std::identity, class Proj2 = std::identity>
requires std::mergeable<I1, I2, O, Comp, Proj1, Proj2>
constexpr ranges::set_symmetric_difference_result<I1, I2, O>
operator()(I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {}) const
{
while (!(first1 == last1 or first2 == last2))
{
if (std::invoke(comp, std::invoke(proj1, *first1), std::invoke(proj2, *first2)))
{
*result = *first1;
++first1;
++result;
}
else if (std::invoke(comp, std::invoke(proj2, *first2),
std::invoke(proj1, *first1)))
{
*result = *first2;
++first2;
++result;
}
else
{
++first1;
++first2;
}
}
auto res1 {ranges::copy(std::move(first1), std::move(last1), std::move(result))};
auto res2 {ranges::copy(std::move(first2), std::move(last2), std::move(res1.out))};
return {std::move(res1.in), std::move(res2.in), std::move(res2.out)};
}
template<ranges::input_range R1, ranges::input_range R2,
std::weakly_incrementable O, class Comp = ranges::less,
class Proj1 = std::identity, class Proj2 = std::identity>
requires std::mergeable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
O, Comp, Proj1, Proj2>
constexpr ranges::set_symmetric_difference_result<
ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>, O>
operator()(R1&& r1, R2&& r2, O result, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {}) const
{
return (*this)(ranges::begin(r1), ranges::end(r1),
ranges::begin(r2), ranges::end(r2),
std::move(result), std::move(comp),
std::move(proj1), std::move(proj2));
}
};
inline constexpr set_symmetric_difference_fn set_symmetric_difference {};
Examples
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
void visualize_this(const auto& v, int min = 1, int max = 9)
{
for (auto i {min}; i <= max; ++i)
{
std::ranges::binary_search(v, i) ? std::cout << i : std::cout << '.';
std::cout << ' ';
}
std::cout << '\n';
}
int main()
{
const auto in1 = {1, 3, 4, 6, 7, 9};
const auto in2 = {1, 4, 5, 6, 9};
std::vector<int> out {};
std::ranges::set_symmetric_difference(in1, in2, std::back_inserter(out));
visualize_this(in1);
visualize_this(in2);
visualize_this(out);
}
1 . 3 4 . 6 7 . 9
1 . . 4 5 6 . . 9
. . 3 . 5 . 7 . .
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