Since lists allow fast insertion and erasing from the middle of a list, certain operations are provided specifically for them.266
list provides three splice operations that destructively move elements from one list to another. The behavior of splice operations is undefined if get_allocator() != x.get_allocator().
void splice(const_iterator position, list& x);
void splice(const_iterator position, list&& x);
Requires: &x != this.
Effects: Inserts the contents of x before position and x becomes empty. Pointers and references to the moved elements of x now refer to those same elements but as members of *this. Iterators referring to the moved elements will continue to refer to their elements, but they now behave as iterators into *this, not into x.
Throws: Nothing.
Complexity: Constant time.
void splice(const_iterator position, list& x, const_iterator i);
void splice(const_iterator position, list&& x, const_iterator i);
Effects: Inserts an element pointed to by i from list x before position and removes the element from x. The result is unchanged if position == i or position == ++i. Pointers and references to *i continue to refer to this same element but as a member of *this. Iterators to *i (including i itself) continue to refer to the same element, but now behave as iterators into *this, not into x.
Requires: i is a valid dereferenceable iterator of x.
Throws: Nothing.
Complexity: Constant time.
void splice(const_iterator position, list& x, const_iterator first,
const_iterator last);
void splice(const_iterator position, list&& x, const_iterator first,
const_iterator last);
Effects: Inserts elements in the range [first,last) before position and removes the elements from x.
Requires: [first, last) is a valid range in x. The result is undefined if position is an iterator in the range [first,last). Pointers and references to the moved elements of x now refer to those same elements but as members of *this. Iterators referring to the moved elements will continue to refer to their elements, but they now behave as iterators into *this, not into x.
Throws: Nothing.
Complexity: Constant time if &x == this; otherwise, linear time.
void remove(const T& value);
template <class Predicate> void remove_if(Predicate pred);
Effects: Erases all the elements in the list referred by a list iterator i for which the following conditions hold: *i == value, pred(*i) != false. Invalidates only the iterators and references to the erased elements.
Throws: Nothing unless an exception is thrown by *i == value or pred(*i) != false.
Remarks: Stable ([algorithm.stable]).
Complexity: Exactly size() applications of the corresponding predicate.
void unique();
template <class BinaryPredicate> void unique(BinaryPredicate binary_pred);
Effects: Erases all but the first element from every consecutive group of equal elements referred to by the iterator i in the range [first + 1,last) for which *i == *(i-1) (for the version of unique with no arguments) or pred(*i, *(i - 1)) (for the version of unique with a predicate argument) holds. Invalidates only the iterators and references to the erased elements.
Throws: Nothing unless an exception is thrown by *i == *(i-1) or pred(*i, *(i - 1))
Complexity: If the range [first, last) is not empty, exactly (last - first) - 1 applications of the corresponding predicate, otherwise no applications of the predicate.
void merge(list& x);
void merge(list&& x);
template <class Compare> void merge(list& x, Compare comp);
template <class Compare> void merge(list&& x, Compare comp);
Requires: comp shall define a strict weak ordering ([alg.sorting]), and both the list and the argument list shall be sorted according to this ordering.
Effects: If (&x == this) does nothing; otherwise, merges the two sorted ranges [begin(), end()) and [x.begin(), x.end()). The result is a range in which the elements will be sorted in non-decreasing order according to the ordering defined by comp; that is, for every iterator i, in the range other than the first, the condition comp(*i, *(i - 1)) will be false. Pointers and references to the moved elements of x now refer to those same elements but as members of *this. Iterators referring to the moved elements will continue to refer to their elements, but they now behave as iterators into *this, not into x.
Remarks: Stable ([algorithm.stable]). If (&x != this) the range [x.begin(), x.end()) is empty after the merge. No elements are copied by this operation. The behavior is undefined if this->get_allocator() != x.get_allocator().
Complexity: At most size() + x.size() - 1 applications of comp if (&x != this); otherwise, no applications of comp are performed. If an exception is thrown other than by a comparison there are no effects.
Effects: Reverses the order of the elements in the list. Does not affect the validity of iterators and references.
Complexity: Linear time.
void sort();
template <class Compare> void sort(Compare comp);
Requires: operator< (for the first version) or comp (for the second version) shall define a strict weak ordering ([alg.sorting]).
Effects: Sorts the list according to the operator< or a Compare function object. Does not affect the validity of iterators and references.
Remarks: Stable ([algorithm.stable]).
Complexity: Approximately N log(N) comparisons, where N == size().
As specified in [allocator.requirements], the requirements in this Clause apply only to lists whose allocators compare equal.