diff -r 809581724cc7 -r 0358f1d9c506 ucx/linked_list.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ucx/linked_list.c	Mon May 22 16:17:26 2023 +0200
@@ -0,0 +1,927 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "cx/linked_list.h"
+#include "cx/utils.h"
+#include <string.h>
+#include <assert.h>
+
+// LOW LEVEL LINKED LIST FUNCTIONS
+
+#define CX_LL_PTR(cur, off) (*(void**)(((char*)(cur))+(off)))
+#define ll_prev(node) CX_LL_PTR(node, loc_prev)
+#define ll_next(node) CX_LL_PTR(node, loc_next)
+#define ll_advance(node) CX_LL_PTR(node, loc_advance)
+#define ll_data(node) (((char*)(node))+loc_data)
+
+void *cx_linked_list_at(
+        void const *start,
+        size_t start_index,
+        ptrdiff_t loc_advance,
+        size_t index
+) {
+    assert(start != NULL);
+    assert(loc_advance >= 0);
+    size_t i = start_index;
+    void const *cur = start;
+    while (i != index && cur != NULL) {
+        cur = ll_advance(cur);
+        i < index ? i++ : i--;
+    }
+    return (void *) cur;
+}
+
+ssize_t cx_linked_list_find(
+        void const *start,
+        ptrdiff_t loc_advance,
+        ptrdiff_t loc_data,
+        cx_compare_func cmp_func,
+        void const *elem
+) {
+    assert(start != NULL);
+    assert(loc_advance >= 0);
+    assert(loc_data >= 0);
+    assert(cmp_func);
+
+    void const *node = start;
+    ssize_t index = 0;
+    do {
+        void *current = ll_data(node);
+        if (cmp_func(current, elem) == 0) {
+            return index;
+        }
+        node = ll_advance(node);
+        index++;
+    } while (node != NULL);
+    return -1;
+}
+
+void *cx_linked_list_first(
+        void const *node,
+        ptrdiff_t loc_prev
+) {
+    return cx_linked_list_last(node, loc_prev);
+}
+
+void *cx_linked_list_last(
+        void const *node,
+        ptrdiff_t loc_next
+) {
+    assert(node != NULL);
+    assert(loc_next >= 0);
+
+    void const *cur = node;
+    void const *last;
+    do {
+        last = cur;
+    } while ((cur = ll_next(cur)) != NULL);
+
+    return (void *) last;
+}
+
+void *cx_linked_list_prev(
+        void const *begin,
+        ptrdiff_t loc_next,
+        void const *node
+) {
+    assert(begin != NULL);
+    assert(node != NULL);
+    assert(loc_next >= 0);
+    if (begin == node) return NULL;
+    void const *cur = begin;
+    void const *next;
+    while (1) {
+        next = ll_next(cur);
+        if (next == node) return (void *) cur;
+        cur = next;
+    }
+}
+
+void cx_linked_list_link(
+        void *left,
+        void *right,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next
+) {
+    assert(loc_next >= 0);
+    ll_next(left) = right;
+    if (loc_prev >= 0) {
+        ll_prev(right) = left;
+    }
+}
+
+void cx_linked_list_unlink(
+        void *left,
+        void *right,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next
+) {
+    assert (loc_next >= 0);
+    assert(ll_next(left) == right);
+    ll_next(left) = NULL;
+    if (loc_prev >= 0) {
+        assert(ll_prev(right) == left);
+        ll_prev(right) = NULL;
+    }
+}
+
+void cx_linked_list_add(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        void *new_node
+) {
+    void *last;
+    if (end == NULL) {
+        assert(begin != NULL);
+        last = *begin == NULL ? NULL : cx_linked_list_last(*begin, loc_next);
+    } else {
+        last = *end;
+    }
+    cx_linked_list_insert_chain(begin, end, loc_prev, loc_next, last, new_node, new_node);
+}
+
+void cx_linked_list_prepend(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        void *new_node
+) {
+    cx_linked_list_insert_chain(begin, end, loc_prev, loc_next, NULL, new_node, new_node);
+}
+
+void cx_linked_list_insert(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        void *node,
+        void *new_node
+) {
+    cx_linked_list_insert_chain(begin, end, loc_prev, loc_next, node, new_node, new_node);
+}
+
+void cx_linked_list_insert_chain(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        void *node,
+        void *insert_begin,
+        void *insert_end
+) {
+    // find the end of the chain, if not specified
+    if (insert_end == NULL) {
+        insert_end = cx_linked_list_last(insert_begin, loc_next);
+    }
+
+    // determine the successor
+    void *successor;
+    if (node == NULL) {
+        assert(begin != NULL || (end != NULL && loc_prev >= 0));
+        if (begin != NULL) {
+            successor = *begin;
+            *begin = insert_begin;
+        } else {
+            successor = *end == NULL ? NULL : cx_linked_list_first(*end, loc_prev);
+        }
+    } else {
+        successor = ll_next(node);
+        cx_linked_list_link(node, insert_begin, loc_prev, loc_next);
+    }
+
+    if (successor == NULL) {
+        // the list ends with the new chain
+        if (end != NULL) {
+            *end = insert_end;
+        }
+    } else {
+        cx_linked_list_link(insert_end, successor, loc_prev, loc_next);
+    }
+}
+
+void cx_linked_list_remove(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        void *node
+) {
+    assert(node != NULL);
+    assert(loc_next >= 0);
+    assert(loc_prev >= 0 || begin != NULL);
+
+    // find adjacent nodes
+    void *next = ll_next(node);
+    void *prev;
+    if (loc_prev >= 0) {
+        prev = ll_prev(node);
+    } else {
+        prev = cx_linked_list_prev(*begin, loc_next, node);
+    }
+
+    // update next pointer of prev node, or set begin
+    if (prev == NULL) {
+        if (begin != NULL) {
+            *begin = next;
+        }
+    } else {
+        ll_next(prev) = next;
+    }
+
+    // update prev pointer of next node, or set end
+    if (next == NULL) {
+        if (end != NULL) {
+            *end = prev;
+        }
+    } else if (loc_prev >= 0) {
+        ll_prev(next) = prev;
+    }
+}
+
+size_t cx_linked_list_size(
+        void const *node,
+        ptrdiff_t loc_next
+) {
+    assert(loc_next >= 0);
+    size_t size = 0;
+    while (node != NULL) {
+        node = ll_next(node);
+        size++;
+    }
+    return size;
+}
+
+#ifndef CX_LINKED_LIST_SORT_SBO_SIZE
+#define CX_LINKED_LIST_SORT_SBO_SIZE 1024
+#endif
+
+static void cx_linked_list_sort_merge(
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        ptrdiff_t loc_data,
+        size_t length,
+        void *ls,
+        void *le,
+        void *re,
+        cx_compare_func cmp_func,
+        void **begin,
+        void **end
+) {
+    void *sbo[CX_LINKED_LIST_SORT_SBO_SIZE];
+    void **sorted = length >= CX_LINKED_LIST_SORT_SBO_SIZE ?
+                    malloc(sizeof(void *) * length) : sbo;
+    if (sorted == NULL) abort();
+    void *rc, *lc;
+
+    lc = ls;
+    rc = le;
+    size_t n = 0;
+    while (lc && lc != le && rc != re) {
+        if (cmp_func(ll_data(lc), ll_data(rc)) <= 0) {
+            sorted[n] = lc;
+            lc = ll_next(lc);
+        } else {
+            sorted[n] = rc;
+            rc = ll_next(rc);
+        }
+        n++;
+    }
+    while (lc && lc != le) {
+        sorted[n] = lc;
+        lc = ll_next(lc);
+        n++;
+    }
+    while (rc && rc != re) {
+        sorted[n] = rc;
+        rc = ll_next(rc);
+        n++;
+    }
+
+    // Update pointer
+    if (loc_prev >= 0) ll_prev(sorted[0]) = NULL;
+    cx_for_n (i, length - 1) {
+        cx_linked_list_link(sorted[i], sorted[i + 1], loc_prev, loc_next);
+    }
+    ll_next(sorted[length - 1]) = NULL;
+
+    *begin = sorted[0];
+    *end = sorted[length-1];
+    if (sorted != sbo) {
+        free(sorted);
+    }
+}
+
+void cx_linked_list_sort( // NOLINT(misc-no-recursion) - purposely recursive function
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next,
+        ptrdiff_t loc_data,
+        cx_compare_func cmp_func
+) {
+    assert(begin != NULL);
+    assert(loc_next >= 0);
+    assert(loc_data >= 0);
+    assert(cmp_func);
+
+    void *lc, *ls, *le, *re;
+
+    // set start node
+    ls = *begin;
+
+    // early exit when this list is empty
+    if (ls == NULL) return;
+
+    // check how many elements are already sorted
+    lc = ls;
+    size_t ln = 1;
+    while (ll_next(lc) != NULL && cmp_func(ll_data(ll_next(lc)), ll_data(lc)) > 0) {
+        lc = ll_next(lc);
+        ln++;
+    }
+    le = ll_next(lc);
+
+    // if first unsorted node is NULL, the list is already completely sorted
+    if (le != NULL) {
+        void *rc;
+        size_t rn = 1;
+        rc = le;
+        // skip already sorted elements
+        while (ll_next(rc) != NULL && cmp_func(ll_data(ll_next(rc)), ll_data(rc)) > 0) {
+            rc = ll_next(rc);
+            rn++;
+        }
+        re = ll_next(rc);
+
+        // {ls,...,le->prev} and {rs,...,re->prev} are sorted - merge them
+        void *sorted_begin, *sorted_end;
+        cx_linked_list_sort_merge(loc_prev, loc_next, loc_data,
+                                  ln + rn, ls, le, re, cmp_func,
+                                  &sorted_begin, &sorted_end);
+
+        // Something left? Sort it!
+        size_t remainder_length = cx_linked_list_size(re, loc_next);
+        if (remainder_length > 0) {
+            void *remainder = re;
+            cx_linked_list_sort(&remainder, NULL, loc_prev, loc_next, loc_data, cmp_func);
+
+            // merge sorted list with (also sorted) remainder
+            cx_linked_list_sort_merge(loc_prev, loc_next, loc_data,
+                                      ln + rn + remainder_length,
+                                      sorted_begin, remainder, NULL, cmp_func,
+                                      &sorted_begin, &sorted_end);
+        }
+        *begin = sorted_begin;
+        if (end) *end = sorted_end;
+    }
+}
+
+int cx_linked_list_compare(
+        void const *begin_left,
+        void const *begin_right,
+        ptrdiff_t loc_advance,
+        ptrdiff_t loc_data,
+        cx_compare_func cmp_func
+) {
+    void const *left = begin_left, *right = begin_right;
+
+    while (left != NULL && right != NULL) {
+        void const *left_data = ll_data(left);
+        void const *right_data = ll_data(right);
+        int result = cmp_func(left_data, right_data);
+        if (result != 0) return result;
+        left = ll_advance(left);
+        right = ll_advance(right);
+    }
+
+    if (left != NULL) { return 1; }
+    else if (right != NULL) { return -1; }
+    else { return 0; }
+}
+
+void cx_linked_list_reverse(
+        void **begin,
+        void **end,
+        ptrdiff_t loc_prev,
+        ptrdiff_t loc_next
+) {
+    assert(begin != NULL);
+    assert(loc_next >= 0);
+
+    // swap all links
+    void *prev = NULL;
+    void *cur = *begin;
+    while (cur != NULL) {
+        void *next = ll_next(cur);
+
+        ll_next(cur) = prev;
+        if (loc_prev >= 0) {
+            ll_prev(cur) = next;
+        }
+
+        prev = cur;
+        cur = next;
+    }
+
+    // update begin and end
+    if (end != NULL) {
+        *end = *begin;
+    }
+    *begin = prev;
+}
+
+// HIGH LEVEL LINKED LIST IMPLEMENTATION
+
+bool CX_DISABLE_LINKED_LIST_SWAP_SBO = false;
+
+typedef struct cx_linked_list_node cx_linked_list_node;
+struct cx_linked_list_node {
+    cx_linked_list_node *prev;
+    cx_linked_list_node *next;
+    char payload[];
+};
+
+#define CX_LL_LOC_PREV offsetof(cx_linked_list_node, prev)
+#define CX_LL_LOC_NEXT offsetof(cx_linked_list_node, next)
+#define CX_LL_LOC_DATA offsetof(cx_linked_list_node, payload)
+
+typedef struct {
+    struct cx_list_s base;
+    cx_linked_list_node *begin;
+    cx_linked_list_node *end;
+} cx_linked_list;
+
+static cx_linked_list_node *cx_ll_node_at(
+        cx_linked_list const *list,
+        size_t index
+) {
+    if (index >= list->base.size) {
+        return NULL;
+    } else if (index > list->base.size / 2) {
+        return cx_linked_list_at(list->end, list->base.size - 1, CX_LL_LOC_PREV, index);
+    } else {
+        return cx_linked_list_at(list->begin, 0, CX_LL_LOC_NEXT, index);
+    }
+}
+
+static int cx_ll_insert_at(
+        struct cx_list_s *list,
+        cx_linked_list_node *node,
+        void const *elem
+) {
+
+    // create the new new_node
+    cx_linked_list_node *new_node = cxMalloc(list->allocator,
+                                             sizeof(cx_linked_list_node) + list->item_size);
+
+    // sortir if failed
+    if (new_node == NULL) return 1;
+
+    // initialize new new_node
+    new_node->prev = new_node->next = NULL;
+    memcpy(new_node->payload, elem, list->item_size);
+
+    // insert
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_insert_chain(
+            (void **) &ll->begin, (void **) &ll->end,
+            CX_LL_LOC_PREV, CX_LL_LOC_NEXT,
+            node, new_node, new_node
+    );
+
+    // increase the size and return
+    list->size++;
+    return 0;
+}
+
+static size_t cx_ll_insert_array(
+        struct cx_list_s *list,
+        size_t index,
+        void const *array,
+        size_t n
+) {
+    // out-of bounds and corner case check
+    if (index > list->size || n == 0) return 0;
+
+    // find position efficiently
+    cx_linked_list_node *node = index == 0 ? NULL : cx_ll_node_at((cx_linked_list *) list, index - 1);
+
+    // perform first insert
+    if (0 != cx_ll_insert_at(list, node, array)) {
+        return 1;
+    }
+
+    // is there more?
+    if (n == 1) return 1;
+
+    // we now know exactly where we are
+    node = node == NULL ? ((cx_linked_list *) list)->begin : node->next;
+
+    // we can add the remaining nodes and immedately advance to the inserted node
+    char const *source = array;
+    for (size_t i = 1; i < n; i++) {
+        source += list->item_size;
+        if (0 != cx_ll_insert_at(list, node, source)) {
+            return i;
+        }
+        node = node->next;
+    }
+    return n;
+}
+
+static int cx_ll_insert_element(
+        struct cx_list_s *list,
+        size_t index,
+        void const *element
+) {
+    return 1 != cx_ll_insert_array(list, index, element, 1);
+}
+
+static int cx_ll_remove(
+        struct cx_list_s *list,
+        size_t index
+) {
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_node *node = cx_ll_node_at(ll, index);
+
+    // out-of-bounds check
+    if (node == NULL) return 1;
+
+    // element destruction
+    cx_invoke_destructor(list, node->payload);
+
+    // remove
+    cx_linked_list_remove((void **) &ll->begin, (void **) &ll->end,
+                          CX_LL_LOC_PREV, CX_LL_LOC_NEXT, node);
+
+    // adjust size
+    list->size--;
+
+    // free and return
+    cxFree(list->allocator, node);
+
+    return 0;
+}
+
+static void cx_ll_clear(struct cx_list_s *list) {
+    if (list->size == 0) return;
+
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_node *node = ll->begin;
+    while (node != NULL) {
+        cx_invoke_destructor(list, node->payload);
+        cx_linked_list_node *next = node->next;
+        cxFree(list->allocator, node);
+        node = next;
+    }
+    ll->begin = ll->end = NULL;
+    list->size = 0;
+}
+
+#ifndef CX_LINKED_LIST_SWAP_SBO_SIZE
+#define CX_LINKED_LIST_SWAP_SBO_SIZE 16
+#endif
+
+static int cx_ll_swap(
+        struct cx_list_s *list,
+        size_t i,
+        size_t j
+) {
+    if (i >= list->size || j >= list->size) return 1;
+    if (i == j) return 0;
+
+    // perform an optimized search that finds both elements in one run
+    cx_linked_list *ll = (cx_linked_list *) list;
+    size_t mid = list->size / 2;
+    size_t left, right;
+    if (i < j) {
+        left = i;
+        right = j;
+    } else {
+        left = j;
+        right = i;
+    }
+    cx_linked_list_node *nleft, *nright;
+    if (left < mid && right < mid) {
+        // case 1: both items left from mid
+        nleft = cx_ll_node_at(ll, left);
+        nright = nleft;
+        for (size_t c = left; c < right; c++) {
+            nright = nright->next;
+        }
+    } else if (left >= mid && right >= mid) {
+        // case 2: both items right from mid
+        nright = cx_ll_node_at(ll, right);
+        nleft = nright;
+        for (size_t c = right; c > left; c--) {
+            nleft = nleft->prev;
+        }
+    } else {
+        // case 3: one item left, one item right
+
+        // chose the closest to begin / end
+        size_t closest;
+        size_t other;
+        size_t diff2boundary = list->size - right - 1;
+        if (left <= diff2boundary) {
+            closest = left;
+            other = right;
+            nleft = cx_ll_node_at(ll, left);
+        } else {
+            closest = right;
+            other = left;
+            diff2boundary = left;
+            nright = cx_ll_node_at(ll, right);
+        }
+
+        // is other element closer to us or closer to boundary?
+        if (right - left <= diff2boundary) {
+            // search other element starting from already found element
+            if (closest == left) {
+                nright = nleft;
+                for (size_t c = left; c < right; c++) {
+                    nright = nright->next;
+                }
+            } else {
+                nleft = nright;
+                for (size_t c = right; c > left; c--) {
+                    nleft = nleft->prev;
+                }
+            }
+        } else {
+            // search other element starting at the boundary
+            if (closest == left) {
+                nright = cx_ll_node_at(ll, other);
+            } else {
+                nleft = cx_ll_node_at(ll, other);
+            }
+        }
+    }
+
+    if (list->item_size > CX_LINKED_LIST_SWAP_SBO_SIZE || CX_DISABLE_LINKED_LIST_SWAP_SBO) {
+        cx_linked_list_node *prev = nleft->prev;
+        cx_linked_list_node *next = nright->next;
+        cx_linked_list_node *midstart = nleft->next;
+        cx_linked_list_node *midend = nright->prev;
+
+        if (prev == NULL) {
+            ll->begin = nright;
+        } else {
+            prev->next = nright;
+        }
+        nright->prev = prev;
+        if (midstart == nright) {
+            // special case: both nodes are adjacent
+            nright->next = nleft;
+            nleft->prev = nright;
+        } else {
+            // likely case: a chain is between the two nodes
+            nright->next = midstart;
+            midstart->prev = nright;
+            midend->next = nleft;
+            nleft->prev = midend;
+        }
+        nleft->next = next;
+        if (next == NULL) {
+            ll->end = nleft;
+        } else {
+            next->prev = nleft;
+        }
+    } else {
+        // swap payloads to avoid relinking
+        char buf[CX_LINKED_LIST_SWAP_SBO_SIZE];
+        memcpy(buf, nleft->payload, list->item_size);
+        memcpy(nleft->payload, nright->payload, list->item_size);
+        memcpy(nright->payload, buf, list->item_size);
+    }
+
+    return 0;
+}
+
+static void *cx_ll_at(
+        struct cx_list_s const *list,
+        size_t index
+) {
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_node *node = cx_ll_node_at(ll, index);
+    return node == NULL ? NULL : node->payload;
+}
+
+static ssize_t cx_ll_find(
+        struct cx_list_s const *list,
+        void const *elem
+) {
+    return cx_linked_list_find(((cx_linked_list *) list)->begin,
+                               CX_LL_LOC_NEXT, CX_LL_LOC_DATA,
+                               list->cmpfunc, elem);
+}
+
+static void cx_ll_sort(struct cx_list_s *list) {
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_sort((void **) &ll->begin, (void **) &ll->end,
+                        CX_LL_LOC_PREV, CX_LL_LOC_NEXT, CX_LL_LOC_DATA,
+                        list->cmpfunc);
+}
+
+static void cx_ll_reverse(struct cx_list_s *list) {
+    cx_linked_list *ll = (cx_linked_list *) list;
+    cx_linked_list_reverse((void **) &ll->begin, (void **) &ll->end, CX_LL_LOC_PREV, CX_LL_LOC_NEXT);
+}
+
+static int cx_ll_compare(
+        struct cx_list_s const *list,
+        struct cx_list_s const *other
+) {
+    cx_linked_list *left = (cx_linked_list *) list;
+    cx_linked_list *right = (cx_linked_list *) other;
+    return cx_linked_list_compare(left->begin, right->begin,
+                                  CX_LL_LOC_NEXT, CX_LL_LOC_DATA,
+                                  list->cmpfunc);
+}
+
+static bool cx_ll_iter_valid(void const *it) {
+    struct cx_iterator_s const *iter = it;
+    return iter->elem_handle != NULL;
+}
+
+static void cx_ll_iter_next(void *it) {
+    struct cx_iterator_base_s *itbase = it;
+    if (itbase->remove) {
+        itbase->remove = false;
+        struct cx_mut_iterator_s *iter = it;
+        struct cx_list_s *list = iter->src_handle;
+        cx_linked_list *ll = iter->src_handle;
+        cx_linked_list_node *node = iter->elem_handle;
+        iter->elem_handle = node->next;
+        cx_invoke_destructor(list, node->payload);
+        cx_linked_list_remove((void **) &ll->begin, (void **) &ll->end,
+                              CX_LL_LOC_PREV, CX_LL_LOC_NEXT, node);
+        list->size--;
+        cxFree(list->allocator, node);
+    } else {
+        struct cx_iterator_s *iter = it;
+        iter->index++;
+        cx_linked_list_node *node = iter->elem_handle;
+        iter->elem_handle = node->next;
+    }
+}
+
+static void cx_ll_iter_prev(void *it) {
+    struct cx_iterator_base_s *itbase = it;
+    if (itbase->remove) {
+        itbase->remove = false;
+        struct cx_mut_iterator_s *iter = it;
+        struct cx_list_s *list = iter->src_handle;
+        cx_linked_list *ll = iter->src_handle;
+        cx_linked_list_node *node = iter->elem_handle;
+        iter->elem_handle = node->prev;
+        iter->index--;
+        cx_invoke_destructor(list, node->payload);
+        cx_linked_list_remove((void **) &ll->begin, (void **) &ll->end,
+                              CX_LL_LOC_PREV, CX_LL_LOC_NEXT, node);
+        list->size--;
+        cxFree(list->allocator, node);
+    } else {
+        struct cx_iterator_s *iter = it;
+        iter->index--;
+        cx_linked_list_node *node = iter->elem_handle;
+        iter->elem_handle = node->prev;
+    }
+}
+
+static void *cx_ll_iter_current(void const *it) {
+    struct cx_iterator_s const *iter = it;
+    cx_linked_list_node *node = iter->elem_handle;
+    return node->payload;
+}
+
+static bool cx_ll_iter_flag_rm(void *it) {
+    struct cx_iterator_base_s *iter = it;
+    if (iter->mutating) {
+        iter->remove = true;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+static CxIterator cx_ll_iterator(
+        struct cx_list_s const *list,
+        size_t index,
+        bool backwards
+) {
+    CxIterator iter;
+    iter.index = index;
+    iter.src_handle = list;
+    iter.elem_handle = cx_ll_node_at((cx_linked_list const *) list, index);
+    iter.base.valid = cx_ll_iter_valid;
+    iter.base.current = cx_ll_iter_current;
+    iter.base.next = backwards ? cx_ll_iter_prev : cx_ll_iter_next;
+    iter.base.flag_removal = cx_ll_iter_flag_rm;
+    iter.base.mutating = false;
+    iter.base.remove = false;
+    return iter;
+}
+
+static int cx_ll_insert_iter(
+        CxMutIterator *iter,
+        void const *elem,
+        int prepend
+) {
+    struct cx_list_s *list = iter->src_handle;
+    cx_linked_list_node *node = iter->elem_handle;
+    if (node != NULL) {
+        assert(prepend >= 0 && prepend <= 1);
+        cx_linked_list_node *choice[2] = {node, node->prev};
+        int result = cx_ll_insert_at(list, choice[prepend], elem);
+        iter->index += prepend * (0 == result);
+        return result;
+    } else {
+        int result = cx_ll_insert_element(list, list->size, elem);
+        iter->index = list->size;
+        return result;
+    }
+}
+
+static void cx_ll_destructor(CxList *list) {
+    cx_linked_list *ll = (cx_linked_list *) list;
+
+    cx_linked_list_node *node = ll->begin;
+    while (node) {
+        cx_invoke_destructor(list, node->payload);
+        void *next = node->next;
+        cxFree(list->allocator, node);
+        node = next;
+    }
+
+    cxFree(list->allocator, list);
+}
+
+static cx_list_class cx_linked_list_class = {
+        cx_ll_destructor,
+        cx_ll_insert_element,
+        cx_ll_insert_array,
+        cx_ll_insert_iter,
+        cx_ll_remove,
+        cx_ll_clear,
+        cx_ll_swap,
+        cx_ll_at,
+        cx_ll_find,
+        cx_ll_sort,
+        cx_ll_compare,
+        cx_ll_reverse,
+        cx_ll_iterator,
+};
+
+CxList *cxLinkedListCreate(
+        CxAllocator const *allocator,
+        cx_compare_func comparator,
+        size_t item_size
+) {
+    if (allocator == NULL) {
+        allocator = cxDefaultAllocator;
+    }
+
+    cx_linked_list *list = cxCalloc(allocator, 1, sizeof(cx_linked_list));
+    if (list == NULL) return NULL;
+
+    list->base.cl = &cx_linked_list_class;
+    list->base.allocator = allocator;
+    list->base.cmpfunc = comparator;
+
+    if (item_size > 0) {
+        list->base.item_size = item_size;
+    } else {
+        cxListStorePointers((CxList *) list);
+    }
+
+    return (CxList *) list;
+}