std::deque<T,Allocator>::push_front (3) - Linux Man Pages
void push_front( const T& value );
void push_front( T&& value ); (since C++11)
Prepends the given element value to the beginning of the container.
All iterators, including the past-the-end iterator, are invalidated. No references are invalidated.
value - the value of the element to prepend
If an exception is thrown, this function has no effect (strong exception guarantee).
emplace_front constructs an element in-place at the beginning
push_back (public member function)
pop_front (public member function)