SoTl.hxx

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#ifndef SOTL_HXX
#define SOTL_HXX

// SOTL = SelfOrganising TemplateList

/*
  Copyright by Andrej Konkow 1996

  User has to take care by his own on calling update_pos_no, when inserting
  elements somewhere in the middle. If elements are inserted only at the last
  position the pos is incremented correctly. By default the first element in the list
  has position 1.
  no_of_members is counted and updated automatically.

  Caution:
  This List by default is NOT a selforganizing list. This means that by default an element
  that is being asked for is NOT put at front of the list. This only will be done while the
  flag sotl is set to false(this is default). You can change this flag with the methods
  sotl_list() (sets the flag true) and no_sotl_list() (sets the flag false).

  The List is created by
  List<Typename> *instance_variable = new List<Typename>(sotl_flag);
  ^^^^^^^
  sotl_flag is optional.
  For a normal double linked list
  this flag has not to be set. For
  a selforganizing list : true

  Afterwards the elements can be inserted.
  The User of this list has to delete the elements which are inserted to the list by
  its own.
  The User has only have to work with the List class.
*/

#ifndef _GLIBCXX_CSTDIO
#include <cstdio>
#endif
#ifndef ARBTOOLS_H
#include <arbtools.h>
#endif

typedef unsigned long positiontype;

#define RELATION_GREATER 1
#define RELATION_LESS    2


template <class Type>
class list_elem : virtual Noncopyable {
    positiontype pos;

public:
    list_elem<Type> *next;
    list_elem<Type> *prev;
    Type            *elem;
    bool             isolate_list_elem();                       // set next and prev links to NULp
    // true if isolation has taken place,
    // else false(for example if we're the
    // only element

    Type                        *get_elem()                     { return elem; };
    void                        set_elem(Type *el)              { elem = el; };
    positiontype                get_pos()                       { return pos; };
    void                        set_pos(positiontype p)         { pos = p; };
    list_elem<Type>             *get_next()                     { return next; };
    void                        set_next(list_elem<Type> *n)    { next = n; };
    list_elem<Type>             *get_prev()                     { return prev; };
    void                        set_prev(list_elem<Type> *p)    { prev = p; };

    list_elem();
    list_elem(Type *el);
    ~list_elem();
};


template <class Type>
class List : virtual Noncopyable {
    list_elem<Type>     *first;
    list_elem<Type>     *last;
    list_elem<Type>     *last_asked_list_elem;
    list_elem<Type>     *remembered_elem;

    positiontype        no_of_members;
    bool                sotl;


    list_elem<Type>     *get_list_elem_with_member      (Type *object);
    list_elem<Type>     *get_list_elem_at_pos           (positiontype pos);
    list_elem<Type>     *get_list_elem_at_pos_simple    (positiontype pos);
public:
    // general List functions


    // only use these functions if you know what you are doing !!!  BEGINNING
    list_elem<Type>     *get_first_list_elem()  { return first; };      // do not use !!!
    list_elem<Type>     *get_last_list_elem()   { return last; };       // do not use !!!
    list_elem<Type>     *get_current_list_elem() { return last_asked_list_elem; }; // do not use !!!
    void                remember_current()      { remembered_elem = last_asked_list_elem; };
    void                set_current_ARC(list_elem<Type> *t);            // ARC = and remember current
    void                set_remembered_as_current_ARC();                // ARC = and remember current
    // only use these functions if you know what you are doing !!!  END

    void                sotl_list()             { sotl = true; };
    void                no_sotl_list()          { sotl = false; };
    positiontype        get_no_of_members()     { return no_of_members; };

    positiontype        insert_as_first         (Type *object);
    positiontype        insert_as_last          (Type *object);         // returns pos_no
    positiontype        insert_after_current    (Type *object);
    positiontype        insert_before_current   (Type *object);
    positiontype        insert                  (Type *object);         // returns pos_no
    Type                *get_first              ();
    Type                *get_last               ();
    Type                *get_prev               ();
    Type                *get_next               ();

    void                remove_member_from_list (Type *object);         // object won't be deleted
    void                remove_first();
    void                remove_last();
    List<Type>  *duplicate_list         (Type *object);         // the list is duplicated
    // from the element given til the end.
    // For duplicating the whole list
    // object = get_first(). Only the list is
    // duplicated, not the elems. Caution:
    // In a sotl list the asked element is put
    // to the front. So first make a no_sotl_list()
    // ask and duplicate the list, and then make a
    // sotl_list() again.

    bool                exchange_members        (Type *ex, Type *change);

    /*  following functions only make sense if our list is sorted by the address of
        our item inserted to the list.
        Caution:
        The list is only sorted if it's NOT a sotl list. So take care to
        create or set it to a no_sotl_list().
    */

    // Comment to insert_sorted_by_address_of_object:
    // The function returns the no_of_members in the list.
    // By default an object(the meaning here is that one object equals another,
    // if the address of both objects matches) can be inserted to the list
    // several times. If there is the need to insert an object only once
    // in the list, the flag duplicates has to be set to false.
    // Finally the relation has to be set, by which the list is sorted.
    // The possibilities are : RELATION_GREATER and RELATION_LESS
    positiontype        insert_sorted_by_address_of_object(Type *object,
                                                                int relation=RELATION_LESS,
                                                                bool duplicates=true);

    // Comment to sort_list_join:
    // if an object found in List l is found in this list it won't be inserted
    // a second time.
    void                sort_list_join          (List<Type> *l,
                                                        int relation=RELATION_LESS);    // Lists given as parameter
    // won't be affected
    // Comment to sort_list_subtract:
    // this function call only makes sense if the same element can be found
    // in both lists. The flag relation tells the method how this list(not list l)
    // is sorted. Both lists have to be sorted by the same relation.
    void                sort_list_subtract      (List<Type> *l,
                                                        int relation=RELATION_LESS);



    positiontype        insert_at_pos_simple    (Type *object, positiontype pos);       // returns pos inserted to
    // doesn't refer to get_pos()
    Type                *get_member_at_pos_simple(positiontype pos);

    /*
      Following functions only make sense if the user takes care of the list as
      a numbered list.
    */
    // Comment to insert_at_pos :
    // user does not have to call update_pos_no after insert_at_pos()
    positiontype        insert_at_pos           (Type *object, positiontype pos);       // returns pos inserted to
    positiontype        get_pos_of_member       (Type *object);
    Type                *get_member_at_pos      (positiontype pos);
    bool                remove_pos_from_list    (positiontype pos);             // element won't be deleted
    bool                exchange_positions      (positiontype ex, positiontype change);         // exchange elems in list
    void                update_pos_no(list_elem<Type> *elem, positiontype nr);  // updates no from
    // the given elem with nr til last
    void                update_pos_no();                // updates pos number from first to last

    List(bool so=false);
    ~List();
};

// ------------------
//      list_elem

template <class Type> inline list_elem<Type>::list_elem() {
    pos = 0;
    next = NULp;
    prev = NULp;
    elem = NULp;
}

template <class Type> inline list_elem<Type>::list_elem(Type *el) {
    pos = 0;
    next = NULp;
    prev = NULp;
    elem = el;
}

template <class Type> inline list_elem<Type>::~list_elem() {
    isolate_list_elem();
}

template <class Type> inline  bool list_elem<Type>::isolate_list_elem() {
    if (prev && next) { // somewhere in the middle
        prev->next = next;
        next->prev = prev;
        next       = NULp;
        prev       = NULp;
    }
    else if (prev) { // we're the last
        prev->next = NULp;
        prev       = NULp;
    }
    else if (next) { // we're the first
        next->prev = NULp;
        next       = NULp;
    }
    else {
        return false;
    }
    return true;
}

// -------------
//      List

template <class Type> inline List<Type>::List(bool so) {
    first = last = last_asked_list_elem = remembered_elem = NULp;
    no_of_members = 0;
    sotl = so;
}

template <class Type> inline List<Type>::~List() {
    list_elem<Type> *elem, *help;

    elem = first;
    while (elem) { // delete every object in list
        help = elem->next;
        delete elem;
        elem = help;
    }
}

template <class Type> inline void List<Type>::set_current_ARC(list_elem<Type> *t) { // ARC = and remember current
    remembered_elem = last_asked_list_elem;
    last_asked_list_elem = t;
}

template <class Type> inline void List<Type>::set_remembered_as_current_ARC() { // ARC = and remember current
    list_elem<Type> *mark;

    mark = last_asked_list_elem;
    last_asked_list_elem = remembered_elem;
    remembered_elem = mark;
}

template <class Type> inline list_elem<Type> *List<Type>::get_list_elem_with_member(Type *object) {
    list_elem<Type> *loc_elem;

    loc_elem = first;
    while (loc_elem && loc_elem->elem!=object) {
        loc_elem = loc_elem->next;
    }

    return loc_elem;
}

template <class Type> inline list_elem<Type> *List<Type>::get_list_elem_at_pos(positiontype pos) {
    list_elem<Type> *elem;

    if (pos < 1 || pos > no_of_members)
        return NULp;

    if (! last_asked_list_elem) {
        if (pos > no_of_members/2) {
            elem = last;
            while (elem && elem->get_pos() != pos)
                elem = elem->get_prev();
        }
        else {
            elem = first;
            while (elem && elem->get_pos() != pos)
                elem = elem->next;
        }
    }
    else {
        elem = last_asked_list_elem;

        if (pos >= last_asked_list_elem->get_pos()) {
            while (elem && elem->get_pos() != pos)
                elem = elem->next;
        }
        else { // pos < last_asked_list_elem->pos
            while (elem && elem->get_pos() != pos)
                elem = elem->get_prev();
        }
    }

    return elem;
}

template <class Type> inline list_elem<Type> *List<Type>::get_list_elem_at_pos_simple(positiontype pos) {
    list_elem<Type>         *elem;
    positiontype    counter = 1;

    if (pos < 1 || pos > no_of_members)
        return NULp;

    if (pos > no_of_members/2) {
        elem = last;
        counter = no_of_members;
        while (elem && counter != pos) {
            elem = elem->get_prev();
            counter --;
        }
    }
    else {
        elem = first;
        while (elem && counter != pos) {
            elem = elem->next;
            counter ++;
        }
    }

    return elem;
}

template <class Type> inline Type *List<Type>::get_first() {
    if (first) {
        last_asked_list_elem = first;
        return first->elem;
    }
    else
        return NULp;
}

template <class Type> inline Type *List<Type>::get_last() {
    if (last && ! sotl) { // behavior of a normal linked list
        last_asked_list_elem = last;
        return last->elem;
    }
    else if (last && sotl) {
        last_asked_list_elem = last->get_prev();
        insert_as_first(last->elem);
        remove_last();
        return first->elem;
    }
    else
        return NULp;
}

template <class Type> inline Type *List<Type>::get_prev() {
    Type            *result = NULp;
    list_elem<Type> *mark_prev;

    if (last_asked_list_elem) {

        if (!sotl) { // behavior of a normal linked list
            last_asked_list_elem = last_asked_list_elem->get_prev();

            if (last_asked_list_elem)
                result = last_asked_list_elem->elem;
        }
        else if (sotl) {
            if (last_asked_list_elem) {
                result          = last_asked_list_elem->elem;
                mark_prev       = last_asked_list_elem->get_prev();

                remove_member_from_list(result);
                insert_as_first(result);
                last_asked_list_elem = mark_prev;
            }
        }
    }
    return result;
}

template <class Type> inline Type *List<Type>::get_next() {
    Type            *result = NULp;
    list_elem<Type> *mark_next;

    if (last_asked_list_elem) {

        if (!sotl) { // behavior of a normal linked list
            last_asked_list_elem = last_asked_list_elem->next;

            if (last_asked_list_elem)
                result = last_asked_list_elem->elem;
        }
        else if (sotl) {
            if (last_asked_list_elem) {
                result          = last_asked_list_elem->elem;
                mark_next       = last_asked_list_elem->next;

                remove_member_from_list(result);
                insert_as_first(result);
                last_asked_list_elem = mark_next;
            }
        }
    }

    return result;
}


template <class Type> inline positiontype List<Type>::insert_as_first(Type *object) {
    list_elem<Type> *help = NULp;

    if (! first) { // create first element in list
        first = new list_elem<Type>(object);
        first->set_pos(1);
        last = first;
    }
    else {
        help = new list_elem<Type>(object);
        help->set_pos(1);                               // update by USER !!!
        help->set_next(first);
        first->set_prev(help);
        first = help;
    }

    no_of_members ++;
    return 1;
}

template <class Type> inline  positiontype List<Type>::insert_as_last(Type *object) {
    list_elem<Type> *help = NULp;

    if (! first) { // create first element in list
        first = new list_elem<Type>(object);
        first->set_pos(1);
        last = first;
    }
    else {
        help = new list_elem<Type>(object);
        help->set_pos(no_of_members+1);
        help->set_prev(last);
        last->set_next(help);
        last = help;
    }

    no_of_members ++;
    return no_of_members;
}

template <class Type> inline positiontype List<Type>::insert_after_current(Type *object) {
    list_elem<Type>     *help = NULp;
    positiontype result = 0;

    if (last_asked_list_elem) {

        if (!last_asked_list_elem->get_next()) {
            result = insert_as_last(object);
        }
        else {
            help = new list_elem<Type>(object);
            help->set_pos(last_asked_list_elem->get_pos() + 1);
            help->set_prev(last_asked_list_elem);
            help->set_next(last_asked_list_elem->get_next());
            help->get_next()->set_prev(help);
            last_asked_list_elem->set_next(help);
            last_asked_list_elem = help;

            no_of_members ++;
            result =  no_of_members;
        }
    }
    return result;
}

template <class Type> inline positiontype List<Type>::insert_before_current(Type *object) {
    list_elem<Type>     *help = NULp;
    positiontype result = 0;
    if (last_asked_list_elem) {

        if (!last_asked_list_elem->get_prev()) {
            result = insert_as_first(object);
        }
        else {
            help = new list_elem<Type>(object);
            help->set_pos(last_asked_list_elem->get_pos() - 1);
            help->set_next(last_asked_list_elem);
            help->set_prev(last_asked_list_elem->get_prev());
            help->get_prev()->set_next(help);
            last_asked_list_elem->set_prev(help);
            last_asked_list_elem = help;

            no_of_members ++;
            result = no_of_members;
        }
    }
    return result;
}

template <class Type> inline  positiontype List<Type>::insert(Type *object) {
    return insert_as_first(object);
}

template <class Type> inline positiontype List<Type>::insert_at_pos_simple(Type *object, positiontype temp_pos) {
    // returns pos inserted to
    list_elem<Type> *elem,
        *new_elem;

    if (temp_pos<=1) {
        insert_as_first(object);
        return 1;
    }
    else if (temp_pos>no_of_members) {
        insert_as_last(object);
        return no_of_members;
    }
    else {
        elem = get_list_elem_at_pos_simple(temp_pos);

        new_elem = new list_elem<Type>;
        new_elem->elem = object;
        new_elem->set_pos(temp_pos);
        new_elem->prev = elem->prev;
        new_elem->next = elem;
        elem->prev->next = new_elem;
        elem->prev = new_elem;

        no_of_members ++;
        return temp_pos;
    }
}

template <class Type> inline void List<Type>::remove_member_from_list(Type *object) {
    list_elem<Type> *loc_elem;

    if (last_asked_list_elem && last_asked_list_elem->elem==object) {
        if (! last_asked_list_elem->next)       // we're the last
            last = last_asked_list_elem->get_prev();

        if (! last_asked_list_elem->get_prev())         // we're the first
            first = last_asked_list_elem->next;

        delete last_asked_list_elem;

        if (no_of_members == 1)
            first = last = NULp;

        last_asked_list_elem = NULp;
    }
    else {
        if (last_asked_list_elem &&
            last_asked_list_elem->next &&
            last_asked_list_elem->next->elem == object)
        {
            loc_elem = last_asked_list_elem->next;
        }
        else if (last_asked_list_elem &&
                 last_asked_list_elem->get_prev() &&
                 last_asked_list_elem->get_prev()->elem == object)
        {
            loc_elem = last_asked_list_elem->get_prev();
        }
        else {
            loc_elem = get_list_elem_with_member(object);
        }

        if (! loc_elem)
            return;

        if (! loc_elem->next)   // we're the last
            last = loc_elem->get_prev();

        if (! loc_elem->get_prev())     // we're the first
            first = loc_elem->next;

        delete loc_elem;
    }

    no_of_members --;
}

template <class Type> inline void List<Type>::remove_first() {
    list_elem<Type> *new_first;

    if (no_of_members <= 1) { // case 0 or 1
        delete first;
        first = last = last_asked_list_elem = NULp;
        no_of_members = 0;
    }
    else {
        new_first = first->next;
        delete first;
        first = new_first;
        no_of_members --;
    }
}

template <class Type> inline void List<Type>::remove_last() {
    list_elem<Type> *new_last;

    if (no_of_members <= 1) { // case 0 or 1
        delete last;
        first = last = last_asked_list_elem = NULp;
        no_of_members = 0;
    }
    else {
        new_last = last->get_prev();
        delete last;
        last = new_last;
        no_of_members --;
    }
}

template <class Type> inline positiontype List<Type>::insert_sorted_by_address_of_object(Type *object,
                                                                                          int relation,
                                                                                          bool duplicates)              // falls object schon vorhanden, dann
{
    list_elem<Type> *help = NULp,
        *l_help;

    if (! first) { // create first element in list
        first = new list_elem<Type>(object);
        first->set_pos(1);
        last = first;
    }
    else {
        if (relation == RELATION_GREATER) { // search for a place to insert to objects which are created later,
            l_help = first;                 // have a greater address !!!
            while (l_help && object < l_help->elem)
                l_help = l_help->next;
        }
        else { // RELATION_LESS
            l_help = last;
            while (l_help && object < l_help->elem)
                l_help = l_help->get_prev();
        }

        if (l_help && object == l_help->elem && ! duplicates)   // Element already is in the list
            return no_of_members;

        help = new list_elem<Type>(object);     // generate new element

        if (! l_help) { // new element in front/at end
            if (relation == RELATION_GREATER) {
                last->set_next(help);
                help->set_prev(last);
                last = help;
            }
            else { // RELATION_LESS
                first->set_prev(help);
                help->set_next(first);
                first = help;
            }
        }
        else {
            if (relation == RELATION_GREATER) {
                if (first == l_help)
                    first = help;

                help->set_next(l_help);
                help->set_prev(l_help->get_prev());
            }
            else { // RELATION_LESS
                if (last == l_help)
                    last = help;

                help->set_prev(l_help);
                help->set_next(l_help->next);
            }

            if (help->next)
                help->next->set_prev(help);

            if (help->get_prev())
                help->get_prev()->set_next(help);
        }

    }

    no_of_members ++;

    return no_of_members;
}

template <class Type> inline void List<Type>::sort_list_join(List<Type> *l, int relation) {
    list_elem<Type> *this_list = first,
        *join_list,
        *new_elem;

    if (! l || ! l->get_no_of_members())
        return;

    join_list = l->get_first_list_elem();

    while (this_list && join_list) {
        if (this_list->elem == join_list->elem) {
            this_list = this_list->next;
            join_list = join_list->next;
        }
        else {
            if ((relation == RELATION_GREATER && this_list->elem > join_list->elem) ||
                (relation == RELATION_LESS    && this_list->elem < join_list->elem))
            {
                this_list = this_list->next;
            }
            else
            {
                new_elem = new list_elem<Type>(join_list->elem);
                new_elem->set_prev(this_list->get_prev());
                new_elem->set_next(this_list);
                this_list->set_prev(new_elem);

                if (new_elem->get_prev())
                    new_elem->get_prev()->set_next(new_elem);
                else
                    first = new_elem;

                join_list = join_list->next;

                no_of_members ++;
            }
        }
    }

    if (! join_list || (!this_list && !join_list))
        return;

    if (!this_list) {
        while (join_list) {
            new_elem = new list_elem<Type>(join_list->elem);
            new_elem->set_prev(last);

            if (last)
                last->set_next(new_elem);

            if (!first)
                first = new_elem;

            last = new_elem;
            no_of_members ++;
            join_list = join_list->next;
        }
    }
}

template <class Type> inline  void List<Type>::sort_list_subtract(List<Type> *l, int relation) {
    list_elem<Type> *this_list = first,
        *join_list = l->get_first_list_elem(),
        *mark;

    while (this_list && join_list) {
        if ((relation == RELATION_GREATER && this_list->elem > join_list->elem) ||
            (relation == RELATION_LESS    && this_list->elem < join_list->elem))
        {
            this_list = this_list->next;
        }
        else if ((relation == RELATION_GREATER && this_list->elem < join_list->elem) ||
                 (relation == RELATION_LESS    && this_list->elem > join_list->elem))
        {
            join_list = join_list->next;
        }
        else if (this_list->elem == join_list->elem) { // same element => delete from this_list
            if (this_list == first)
                first = this_list->next;

            if (this_list == last)
                last = this_list->get_prev();

            mark = this_list->next;
            delete this_list;
            this_list = mark;

            join_list = join_list->next;
            no_of_members --;

            if (! no_of_members) {
                last_asked_list_elem = NULp;
                return;
            }
        }
    }
}

template <class Type> inline List<Type> *List<Type>::duplicate_list(Type *object) {
    list_elem<Type> *help_l = first;
    List<Type>      *new_list = NULp;

    if (last_asked_list_elem->elem == object)
        help_l = last_asked_list_elem;
    else
        help_l = get_list_elem_with_member(object);

    if (help_l)
        new_list = new List<Type>;

    while (help_l) {
        new_list->insert_as_last(help_l->elem);

        help_l = help_l->next;
    }

    return new_list;
}

template <class Type>  inline void List<Type>::update_pos_no(list_elem<Type> *elem, positiontype nr) {
    list_elem<Type> *mark;

    if (!elem)
        return;

    elem->set_pos(nr++);
    mark = elem->next;
    while (mark) {
        mark->set_pos(nr++);
        mark = mark->next;
    }
}

template <class Type> inline void List<Type>::update_pos_no() {
    update_pos_no(first, 1);
}

template <class Type> inline bool List<Type>::exchange_members(Type *ex, Type *change) {
    list_elem<Type> *one, *two;
    bool result = false;
    while (1) {
        if (!ex || !change)
            break;

        if (last_asked_list_elem && last_asked_list_elem->elem == ex)
            one = last_asked_list_elem;
        else
            one = get_list_elem_with_member(ex);

        if (! one)
            break;

        if (last_asked_list_elem && last_asked_list_elem->elem == change)
            two = last_asked_list_elem;
        else
            two = get_list_elem_with_member(change);

        if (!two)
            break;

        one->set_elem(change);
        two->set_elem(ex);
        result = true;
        break;
    }

    return result;
}

template <class Type> inline bool List<Type>::exchange_positions(positiontype ex, positiontype change) {
    list_elem<Type> *one, *two;
    Type            *dummy;
    bool    result = false;
    while (1) {
        if (ex < 1 || ex > no_of_members ||
                change < 1 || change > no_of_members)
            break;

        one = get_list_elem_at_pos(ex);
        if (! one)
            break;

        two = get_list_elem_at_pos(change);
        if (!two)
            break;

        dummy = one->elem;
        one->elem = two->elem;
        two->elem = dummy;
        result = true;
        break;
    }
    return result;
}

template <class Type> inline positiontype List<Type>::get_pos_of_member(Type *object) {
    list_elem<Type> *elem;

    if (!object)
        return 0;

    if (last_asked_list_elem && last_asked_list_elem->elem == object) {
        return last_asked_list_elem->get_pos();
    }
    else {
        elem = first;
        while (elem && elem->elem != object)
            elem = elem->next;

        if (elem)
            return elem->get_pos();
        else
            return 0;
    }
}


template <class Type> inline positiontype List<Type>::insert_at_pos(Type *object, positiontype pos) {
    // returns pos inserted to
    list_elem<Type> *elem,
        *new_elem;
    positiontype result;

    elem = get_list_elem_at_pos(pos);

    if (! elem) {
        insert_as_last(object);
        result = last->get_pos();
    }
    else {
        new_elem = new list_elem<Type>(object);
        new_elem->set_prev(elem->get_prev());
        new_elem->set_next(elem);

        if (elem->get_prev())
            elem->get_prev()->set_next(new_elem);

        elem->set_prev(new_elem);

        if (first == elem)
            first = new_elem;

        update_pos_no (new_elem, pos);

        result =  pos;
    }
    return result;
}

template <class Type> inline Type *List<Type>::get_member_at_pos(positiontype pos) {
    list_elem<Type> *elem;

    elem = get_list_elem_at_pos(pos);

    if (elem) {
        last_asked_list_elem = elem;
        return elem->elem;
    }
    else
        return NULp;
}

template <class Type> inline Type *List<Type>::get_member_at_pos_simple(positiontype pos) {
    list_elem<Type> *elem;

    elem = get_list_elem_at_pos_simple(pos);

    if (elem) {
        last_asked_list_elem = elem;
        return elem->elem;
    }
    else
        return NULp;
}

template <class Type> inline bool List<Type>::remove_pos_from_list(positiontype pos) {
    list_elem<Type> *loc_elem;
    bool result = false;
    while (1) {
        if (pos < 1 || pos > no_of_members)
            break;

        loc_elem = last_asked_list_elem;

        if (loc_elem && loc_elem->get_pos() == pos)
            last_asked_list_elem = NULp;
        else {
            if (! (loc_elem = get_list_elem_at_pos(pos)))
                break;
        }

        if (last == loc_elem)
            last = last->get_prev();

        if (first == loc_elem)


            first = first->next;

        delete loc_elem;
        no_of_members --;
        result = true;
        break;
    }

    return result;
}

#else
#error SoTl.hxx included twice
#endif