12 KiB
[list.ops]
23 Containers library [containers]
23.3 Sequence containers [sequences]
23.3.11 Class template list [list]
23.3.11.5 Operations [list.ops]
Since lists allow fast insertion and erasing from the middle of a list, certain operations are provided specifically for them.196
In this subclause, arguments for a template parameter named Predicate or BinaryPredicate shall meet the corresponding requirements in [algorithms.requirements].
The semantics of i + n and i - n, where i is an iterator into the list and n is an integer, are the same as those of next(i, n) and prev(i, n), respectively.
For merge and sort, the definitions and requirements in [alg.sorting] apply.
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().
constexpr void splice(const_iterator position, list& x); constexpr void splice(const_iterator position, list&& x);
Preconditions: addressof(x) != this is true.
Effects: Inserts the contents ofx beforeposition andx becomes empty.
Pointers and references to the moved elements ofx 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 intox.
Throws: Nothing.
Complexity: Constant time.
constexpr void splice(const_iterator position, list& x, const_iterator i); constexpr void splice(const_iterator position, list&& x, const_iterator i);
Preconditions: i is a valid dereferenceable iterator of x.
Effects: Inserts an element pointed to byi from listx before position and removes the element fromx.
The result is unchanged ifposition == i orposition == ++i.
Pointers and references toi continue to refer to this same element but as a member ofthis.
Iterators toi (includingi itself) continue to refer to the same element, but now behave as iterators intothis, not intox.
Throws: Nothing.
Complexity: Constant time.
constexpr void splice(const_iterator position, list& x, const_iterator first, const_iterator last); constexpr void splice(const_iterator position, list&& x, const_iterator first, const_iterator last);
Preconditions: [first, last) is a valid range in x.
position is not an iterator in the range [first, last).
Effects: Inserts elements in the range [first, last) beforeposition and removes the elements fromx.
Pointers and references to the moved elements ofx 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 intox.
Throws: Nothing.
Complexity: Constant time ifaddressof(x) == this; otherwise, linear time.
constexpr size_type remove(const T& value); template<class Predicate> constexpr size_type remove_if(Predicate pred);
Effects: Erases all the elements in the list referred to 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.
Returns: The number of elements erased.
Throws: Nothing unless an exception is thrown by*i == value orpred(*i) != false.
Complexity: Exactlysize() applications of the corresponding predicate.
constexpr size_type unique(); template<class BinaryPredicate> constexpr size_type unique(BinaryPredicate binary_pred);
Let binary_pred be equal_to<>{} for the first overload.
Preconditions: binary_pred is an equivalence relation.
Effects: Erases all but the first element from every consecutive group of equivalent elements.
That is, for a nonempty list, erases all elements referred to by the iterator i in the range [begin() + 1, end()) for which binary_pred(*i, *(i - 1)) is true.
Invalidates only the iterators and references to the erased elements.
Returns: The number of elements erased.
Throws: Nothing unless an exception is thrown by the predicate.
Complexity: If empty() is false, exactly size() - 1 applications of the corresponding predicate, otherwise no applications of the predicate.
constexpr void merge(list& x); constexpr void merge(list&& x); template<class Compare> constexpr void merge(list& x, Compare comp); template<class Compare> constexpr void merge(list&& x, Compare comp);
Let comp be less<> for the first two overloads.
Preconditions: *this and x are both sorted with respect to the comparator comp, andget_allocator() == x.get_allocator() is true.
Effects: If addressof(x) == this, there are no effects.
Otherwise, merges the two sorted ranges [begin(), end()) and [x.begin(), x.end()).
The result is a range that is sorted with respect to the comparator comp.
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 intox.
Complexity: At most size() + x.size() - 1 comparisons if addressof(x) != this; otherwise, no comparisons are performed.
Remarks: Stable ([algorithm.stable]).
If addressof(x) != this, x is empty after the merge.
No elements are copied by this operation.
If an exception is thrown other than by a comparison, there are no effects.
constexpr void reverse() noexcept;
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);
Effects: Sorts the list according to the operator< or a Compare function object.
If an exception is thrown, the order of the elements in *this is unspecified.
Does not affect the validity of iterators and references.
Complexity: ApproximatelyNlogN comparisons, where N is size().
As specified in [allocator.requirements], the requirements in this Clause apply only to lists whose allocators compare equal.