std::forward_list<T,Allocator>::splice_after

void splice_after( const_iterator pos, forward_list& other );	(1)	(since C++11)
void splice_after( const_iterator pos, forward_list&& other );	(2)	(since C++11)
void splice_after( const_iterator pos, forward_list& other, const_iterator it );	(3)	(since C++11)
void splice_after( const_iterator pos, forward_list&& other, const_iterator it );	(4)	(since C++11)
void splice_after( const_iterator pos, forward_list& other, const_iterator first, const_iterator last );	(5)	(since C++11)
void splice_after( const_iterator pos, forward_list&& other, const_iterator first, const_iterator last );	(6)	(since C++11)

Moves elements from another forward_list to *this. The elements are inserted after the element pointed to by pos.

No elements are copied. No iterators or references become invalidated. The iterators to the moved elements now refer into *this, not into other.

1,2) Moves all elements from other into *this. The container other becomes empty after the operation.

3,4) Moves the element pointed to by the iterator following it from other into *this. Has no effect if pos == it or if pos == ++it.

5,6) Moves the elements in the range (first, last) from other into *this. The element pointed-to by first is not moved.

The behavior is undefined if

get_allocator() != other.get_allocator(),
pos is neither before_begin() nor a dereferenceable iterator in [begin(), end()),
for overloads (1,2), *this and other refer to the same object,
for overloads (3,4), the iterator following it is not a dereferenceable iterator into other, or
for overloads (5,6),

(first, last) is not a valid range in other,
some iterators in (first, last) are not dereferenceable, or
pos is in (first, last).

Parameters

pos	-	element after which the content will be inserted
other	-	another container to move the content from
it	-	iterator preceding the iterator to the element to move from `other` to `*this`
first, last	-	the range of elements to move from `other` to `*this`

Return value

(none)

Exceptions

Throws nothing.

Complexity

1,2) Linear in the size of other.

3,4) Constant.

5,6) Linear in std::distance(first, last).

Example

#include <cassert>
#include <forward_list>
 
int main()
{
    using F = std::forward_list<int>;
 
    // Demonstrate the meaning of open range (first, last)
    // in overload (5): the first element of l1 is not moved.
    F l1 = {1, 2, 3, 4, 5};
    F l2 = {10, 11, 12};
 
    l2.splice_after(l2.cbegin(), l1, l1.cbegin(), l1.cend());
    // Not equivalent to l2.splice_after(l2.cbegin(), l1);
    // which is equivalent to
    // l2.splice_after(l2.cbegin(), l1, l1.cbefore_begin(), l1.end());
 
    assert((l1 == F{1}));
    assert((l2 == F{10, 2, 3, 4, 5, 11, 12}));
 
    // Overload (1)
    F x = {1, 2, 3, 4, 5};
    F y = {10, 11, 12};
    x.splice_after(x.cbegin(), y);
    assert((x == F{1, 10, 11, 12, 2, 3, 4, 5}));
    assert((y == F{}));
 
    // Overload (3)
    x = {1, 2, 3, 4, 5};
    y = {10, 11, 12};
    x.splice_after(x.cbegin(), y, y.cbegin());
    assert((x == F{1, 11, 2, 3, 4, 5}));
    assert((y == F{10, 12}));
 
    // Overload (5)
    x = {1, 2, 3, 4, 5};
    y = {10, 11, 12};
    x.splice_after(x.cbegin(), y, y.cbegin(), y.cend());
    assert((x == F{1, 11, 12, 2, 3, 4, 5}));
    assert((y == F{10}));
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2045	C++11	O(1) splicing could not be guaranteed if `get_allocator() != other.get_allocator()`	the behavior is undefined in this case

merge	merges two sorted lists (public member function)
removeremove_if	removes elements satisfying specific criteria (public member function)
before_begincbefore_begin	returns an iterator to the element before beginning (public member function)