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487 lines
16 KiB
C++
487 lines
16 KiB
C++
/**********************************************************************
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* File: elst2.cpp (Formerly elist2.c)
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* Description: Doubly linked embedded list code not in the include file.
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* Author: Phil Cheatle
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*
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* (C) Copyright 1991, Hewlett-Packard Ltd.
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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** http://www.apache.org/licenses/LICENSE-2.0
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*
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**********************************************************************/
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#include <cstdlib>
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#include "elst2.h"
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/***********************************************************************
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* MEMBER FUNCTIONS OF CLASS: ELIST2
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* =================================
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**********************************************************************/
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/***********************************************************************
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* ELIST2::internal_clear
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*
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* Used by the destructor and the "clear" member function of derived list
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* classes to destroy all the elements on the list.
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* The calling function passes a "zapper" function which can be called to
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* delete each element of the list, regardless of its derived type. This
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* technique permits a generic clear function to destroy elements of
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* different derived types correctly, without requiring virtual functions and
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* the consequential memory overhead.
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**********************************************************************/
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void
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ELIST2::internal_clear ( //destroy all links
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void (*zapper) (ELIST2_LINK *)) {
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//ptr to zapper functn
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ELIST2_LINK *ptr;
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ELIST2_LINK *next;
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if (!empty ()) {
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ptr = last->next; //set to first
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last->next = nullptr; //break circle
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last = nullptr; //set list empty
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while (ptr) {
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next = ptr->next;
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zapper(ptr);
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ptr = next;
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}
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}
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}
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/***********************************************************************
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* ELIST2::assign_to_sublist
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*
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* The list is set to a sublist of another list. "This" list must be empty
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* before this function is invoked. The two iterators passed must refer to
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* the same list, different from "this" one. The sublist removed is the
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* inclusive list from start_it's current position to end_it's current
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* position. If this range passes over the end of the source list then the
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* source list has its end set to the previous element of start_it. The
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* extracted sublist is unaffected by the end point of the source list, its
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* end point is always the end_it position.
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**********************************************************************/
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void ELIST2::assign_to_sublist( //to this list
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ELIST2_ITERATOR *start_it, //from list start
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ELIST2_ITERATOR *end_it) { //from list end
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const ERRCODE LIST_NOT_EMPTY =
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"Destination list must be empty before extracting a sublist";
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if (!empty ())
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LIST_NOT_EMPTY.error ("ELIST2.assign_to_sublist", ABORT, nullptr);
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last = start_it->extract_sublist (end_it);
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}
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/***********************************************************************
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* ELIST2::length
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*
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* Return count of elements on list
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**********************************************************************/
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int32_t ELIST2::length() const { // count elements
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ELIST2_ITERATOR it(const_cast<ELIST2*>(this));
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int32_t count = 0;
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for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ())
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count++;
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return count;
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}
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/***********************************************************************
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* ELIST2::sort
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*
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* Sort elements on list
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* NB If you don't like the const declarations in the comparator, coerce yours:
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* (int (*)(const void *, const void *)
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**********************************************************************/
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void
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ELIST2::sort ( //sort elements
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int comparator ( //comparison routine
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const void *, const void *)) {
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ELIST2_ITERATOR it(this);
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int32_t count;
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ELIST2_LINK **base; //ptr array to sort
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ELIST2_LINK **current;
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int32_t i;
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/* Allocate an array of pointers, one per list element */
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count = length ();
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base = static_cast<ELIST2_LINK **>(malloc (count * sizeof (ELIST2_LINK *)));
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/* Extract all elements, putting the pointers in the array */
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current = base;
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for (it.mark_cycle_pt (); !it.cycled_list (); it.forward ()) {
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*current = it.extract ();
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current++;
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}
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/* Sort the pointer array */
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qsort(base, count, sizeof(*base), comparator);
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/* Rebuild the list from the sorted pointers */
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current = base;
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for (i = 0; i < count; i++) {
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it.add_to_end (*current);
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current++;
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}
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free(base);
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}
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// Assuming list has been sorted already, insert new_link to
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// keep the list sorted according to the same comparison function.
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// Comparison function is the same as used by sort, i.e. uses double
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// indirection. Time is O(1) to add to beginning or end.
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// Time is linear to add pre-sorted items to an empty list.
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void ELIST2::add_sorted(int comparator(const void*, const void*),
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ELIST2_LINK* new_link) {
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// Check for adding at the end.
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if (last == nullptr || comparator(&last, &new_link) < 0) {
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if (last == nullptr) {
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new_link->next = new_link;
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new_link->prev = new_link;
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} else {
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new_link->next = last->next;
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new_link->prev = last;
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last->next = new_link;
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new_link->next->prev = new_link;
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}
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last = new_link;
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} else {
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// Need to use an iterator.
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ELIST2_ITERATOR it(this);
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for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
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ELIST2_LINK* link = it.data();
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if (comparator(&link, &new_link) > 0)
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break;
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}
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if (it.cycled_list())
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it.add_to_end(new_link);
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else
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it.add_before_then_move(new_link);
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}
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}
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/***********************************************************************
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* MEMBER FUNCTIONS OF CLASS: ELIST2_ITERATOR
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* ==========================================
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**********************************************************************/
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/***********************************************************************
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* ELIST2_ITERATOR::forward
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*
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* Move the iterator to the next element of the list.
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* REMEMBER: ALL LISTS ARE CIRCULAR.
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**********************************************************************/
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ELIST2_LINK *ELIST2_ITERATOR::forward() {
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#ifndef NDEBUG
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if (!list)
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NO_LIST.error ("ELIST2_ITERATOR::forward", ABORT, nullptr);
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#endif
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if (list->empty ())
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return nullptr;
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if (current) { //not removed so
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//set previous
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prev = current;
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started_cycling = true;
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// In case next is deleted by another iterator, get it from the current.
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current = current->next;
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}
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else {
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if (ex_current_was_cycle_pt)
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cycle_pt = next;
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current = next;
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}
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#ifndef NDEBUG
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if (!current)
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NULL_DATA.error ("ELIST2_ITERATOR::forward", ABORT, nullptr);
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#endif
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next = current->next;
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#ifndef NDEBUG
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if (!next)
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NULL_NEXT.error ("ELIST2_ITERATOR::forward", ABORT,
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"This is: %p Current is: %p", this, current);
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#endif
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return current;
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}
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/***********************************************************************
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* ELIST2_ITERATOR::backward
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*
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* Move the iterator to the previous element of the list.
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* REMEMBER: ALL LISTS ARE CIRCULAR.
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**********************************************************************/
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ELIST2_LINK *ELIST2_ITERATOR::backward() {
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#ifndef NDEBUG
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if (!list)
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NO_LIST.error ("ELIST2_ITERATOR::backward", ABORT, nullptr);
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#endif
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if (list->empty ())
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return nullptr;
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if (current) { //not removed so
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//set previous
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next = current;
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started_cycling = true;
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// In case prev is deleted by another iterator, get it from current.
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current = current->prev;
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} else {
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if (ex_current_was_cycle_pt)
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cycle_pt = prev;
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current = prev;
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}
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#ifndef NDEBUG
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if (!current)
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NULL_DATA.error ("ELIST2_ITERATOR::backward", ABORT, nullptr);
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if (!prev)
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NULL_PREV.error ("ELIST2_ITERATOR::backward", ABORT,
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"This is: %p Current is: %p", this, current);
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#endif
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prev = current->prev;
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return current;
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}
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/***********************************************************************
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* ELIST2_ITERATOR::data_relative
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*
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* Return the data pointer to the element "offset" elements from current.
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* (This function can't be INLINEd because it contains a loop)
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**********************************************************************/
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ELIST2_LINK *ELIST2_ITERATOR::data_relative( //get data + or - ..
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int8_t offset) { //offset from current
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ELIST2_LINK *ptr;
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#ifndef NDEBUG
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if (!list)
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NO_LIST.error ("ELIST2_ITERATOR::data_relative", ABORT, nullptr);
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if (list->empty ())
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EMPTY_LIST.error ("ELIST2_ITERATOR::data_relative", ABORT, nullptr);
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#endif
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if (offset < 0)
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for (ptr = current ? current : next; offset++ < 0; ptr = ptr->prev);
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else
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for (ptr = current ? current : prev; offset-- > 0; ptr = ptr->next);
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#ifndef NDEBUG
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if (!ptr)
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NULL_DATA.error ("ELIST2_ITERATOR::data_relative", ABORT, nullptr);
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#endif
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return ptr;
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}
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/***********************************************************************
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* ELIST2_ITERATOR::exchange()
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*
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* Given another iterator, whose current element is a different element on
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* the same list list OR an element of another list, exchange the two current
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* elements. On return, each iterator points to the element which was the
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* other iterators current on entry.
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* (This function hasn't been in-lined because its a bit big!)
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**********************************************************************/
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void ELIST2_ITERATOR::exchange( //positions of 2 links
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ELIST2_ITERATOR *other_it) { //other iterator
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const ERRCODE DONT_EXCHANGE_DELETED =
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"Can't exchange deleted elements of lists";
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ELIST2_LINK *old_current;
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#ifndef NDEBUG
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if (!list)
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NO_LIST.error ("ELIST2_ITERATOR::exchange", ABORT, nullptr);
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if (!other_it)
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BAD_PARAMETER.error ("ELIST2_ITERATOR::exchange", ABORT, "other_it nullptr");
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if (!(other_it->list))
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NO_LIST.error ("ELIST2_ITERATOR::exchange", ABORT, "other_it");
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#endif
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/* Do nothing if either list is empty or if both iterators reference the same
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link */
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if ((list->empty ()) ||
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(other_it->list->empty ()) || (current == other_it->current))
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return;
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/* Error if either current element is deleted */
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if (!current || !other_it->current)
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DONT_EXCHANGE_DELETED.error ("ELIST2_ITERATOR.exchange", ABORT, nullptr);
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/* Now handle the 4 cases: doubleton list; non-doubleton adjacent elements
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(other before this); non-doubleton adjacent elements (this before other);
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non-adjacent elements. */
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//adjacent links
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if ((next == other_it->current) ||
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(other_it->next == current)) {
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//doubleton list
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if ((next == other_it->current) &&
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(other_it->next == current)) {
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prev = next = current;
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other_it->prev = other_it->next = other_it->current;
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}
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else { //non-doubleton with
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//adjacent links
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//other before this
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if (other_it->next == current) {
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other_it->prev->next = current;
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other_it->current->next = next;
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other_it->current->prev = current;
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current->next = other_it->current;
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current->prev = other_it->prev;
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next->prev = other_it->current;
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other_it->next = other_it->current;
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prev = current;
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}
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else { //this before other
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prev->next = other_it->current;
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current->next = other_it->next;
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current->prev = other_it->current;
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other_it->current->next = current;
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other_it->current->prev = prev;
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other_it->next->prev = current;
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next = current;
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other_it->prev = other_it->current;
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}
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}
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}
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else { //no overlap
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prev->next = other_it->current;
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current->next = other_it->next;
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current->prev = other_it->prev;
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next->prev = other_it->current;
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other_it->prev->next = current;
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other_it->current->next = next;
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other_it->current->prev = prev;
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other_it->next->prev = current;
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}
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/* update end of list pointer when necessary (remember that the 2 iterators
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may iterate over different lists!) */
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if (list->last == current)
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list->last = other_it->current;
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if (other_it->list->last == other_it->current)
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other_it->list->last = current;
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if (current == cycle_pt)
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cycle_pt = other_it->cycle_pt;
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if (other_it->current == other_it->cycle_pt)
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other_it->cycle_pt = cycle_pt;
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/* The actual exchange - in all cases*/
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old_current = current;
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current = other_it->current;
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other_it->current = old_current;
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}
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/***********************************************************************
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* ELIST2_ITERATOR::extract_sublist()
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*
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* This is a private member, used only by ELIST2::assign_to_sublist.
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* Given another iterator for the same list, extract the links from THIS to
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* OTHER inclusive, link them into a new circular list, and return a
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* pointer to the last element.
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* (Can't inline this function because it contains a loop)
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**********************************************************************/
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ELIST2_LINK *ELIST2_ITERATOR::extract_sublist( //from this current
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ELIST2_ITERATOR *other_it) { //to other current
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#ifndef NDEBUG
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const ERRCODE BAD_EXTRACTION_PTS =
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"Can't extract sublist from points on different lists";
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const ERRCODE DONT_EXTRACT_DELETED =
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"Can't extract a sublist marked by deleted points";
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#endif
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const ERRCODE BAD_SUBLIST = "Can't find sublist end point in original list";
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ELIST2_ITERATOR temp_it = *this;
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ELIST2_LINK *end_of_new_list;
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#ifndef NDEBUG
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if (!other_it)
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BAD_PARAMETER.error ("ELIST2_ITERATOR::extract_sublist", ABORT,
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"other_it nullptr");
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if (!list)
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NO_LIST.error ("ELIST2_ITERATOR::extract_sublist", ABORT, nullptr);
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if (list != other_it->list)
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BAD_EXTRACTION_PTS.error ("ELIST2_ITERATOR.extract_sublist", ABORT, nullptr);
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if (list->empty ())
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EMPTY_LIST.error ("ELIST2_ITERATOR::extract_sublist", ABORT, nullptr);
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if (!current || !other_it->current)
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DONT_EXTRACT_DELETED.error ("ELIST2_ITERATOR.extract_sublist", ABORT,
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nullptr);
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#endif
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ex_current_was_last = other_it->ex_current_was_last = false;
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ex_current_was_cycle_pt = false;
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other_it->ex_current_was_cycle_pt = false;
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temp_it.mark_cycle_pt ();
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do { //walk sublist
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if (temp_it.cycled_list()) // can't find end pt
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BAD_SUBLIST.error ("ELIST2_ITERATOR.extract_sublist", ABORT, nullptr);
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if (temp_it.at_last ()) {
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list->last = prev;
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ex_current_was_last = other_it->ex_current_was_last = true;
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}
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if (temp_it.current == cycle_pt)
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ex_current_was_cycle_pt = true;
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if (temp_it.current == other_it->cycle_pt)
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other_it->ex_current_was_cycle_pt = true;
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temp_it.forward ();
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}
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//do INCLUSIVE list
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while (temp_it.prev != other_it->current);
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//circularise sublist
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other_it->current->next = current;
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//circularise sublist
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current->prev = other_it->current;
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end_of_new_list = other_it->current;
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//sublist = whole list
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if (prev == other_it->current) {
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list->last = nullptr;
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prev = current = next = nullptr;
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other_it->prev = other_it->current = other_it->next = nullptr;
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}
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else {
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prev->next = other_it->next;
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other_it->next->prev = prev;
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current = other_it->current = nullptr;
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next = other_it->next;
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other_it->prev = prev;
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}
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return end_of_new_list;
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}
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