std::forward_list insert_after() method

since C++11

// (1) Non const version only
iterator insert( const_iterator pos, const T& value );

// (2) Non const version only
iterator insert( const_iterator pos, T&& value );

// (3) Non const version only
iterator insert( const_iterator pos, size_type count, const T& value );

// (4) Non const version only
template< class InputIt >
iterator insert( const_iterator pos, InputIt first, InputIt last );

// (5) Non const version only
iterator insert( const_iterator pos, std::initializer_list<T> ilist );

Inserts elements after the specified location in the container.

• (1-2) Inserts value before pos.
• (3) Inserts count copies of the value after the element pointed to by pos.
• (4) Inserts elements from range [ first, last ) after the element pointed to by pos.
  Undefined Behavior

  The behavior is undefined if first and last are iterators into *this.

• (5) Inserts elements from initializer list ilist.

Parameters

• pos - iterator after which the content will be inserted
• value - element value to insert
• count - number of elements to insert
• first, last - the range of elements to insert
• ilist - initializer list to insert the values from

Type requirements

• (4) - InputIt must meet the requirements of LegacyInputIterator.

Return value

• (1-2) Iterator to the inserted value.
• (3) Iterator to the last element inserted, or pos if count == 0.
• (4) Iterator to the last element inserted, or pos if first == last.
• (5) Iterator to the last element inserted, or pos if ilist is empty.

Complexity

• (1-2) Constant - O(1).
• (3) Linear in count - O(count).
• (4) Linear in std::distance(first, last) - O(std::distance(first, last)).
• (5) Linear in ilist.size() - O(ilist.size()).

Exceptions

If an exception is thrown by any operation, the are no effect (strong exception guarantee).

Example

Main.cpp

#include <forward_list>
#include <string>
#include <iostream>
#include <vector>

template<typename T>
std::ostream& operator<<(std::ostream& s, const std::forward_list<T>& v) {
    s.put('[');
    char comma[3] = {'\0', ' ', '\0'};
    for (const auto& e : v) {
        s << comma << e;
        comma[0] = ',';
    }
    return s << ']';
}

int main()
{
    std::forward_list<std::string> words {"the", "frogurt", "is", "also", "cursed"};
    std::cout << "words: " << words << '\n';

    // insert_after (2)
    auto beginIt = words.begin();
    words.insert_after(beginIt, "strawberry");
    std::cout << "words: " << words << '\n';

    // insert_after (3)
    auto anotherIt = beginIt;
    ++anotherIt;
    anotherIt = words.insert_after(anotherIt, 2, "strawberry");
    std::cout << "words: " << words << '\n';

    // insert_after (4)
    std::vector<std::string> V = { "apple", "banana", "cherry"};
    anotherIt = words.insert_after(anotherIt, V.begin(), V.end());
    std::cout << "words: " << words << '\n';

    // insert_after (5)
    words.insert_after(anotherIt, {"jackfruit", "kiwifruit", "lime", "mango"});
    std::cout << "words: " << words << '\n';
}

Output

words: [the, frogurt, is, also, cursed]
words: [the, strawberry, frogurt, is, also, cursed]
words: [the, strawberry, strawberry, strawberry, frogurt, is, also, cursed]
words: [the, strawberry, strawberry, strawberry, apple, banana, cherry, frogurt, is, also, cursed]
words: [the, strawberry, strawberry, strawberry, apple, banana, cherry, jackfruit, kiwifruit, lime, mango, frogurt, is, also, cursed]