universe@850: /*
universe@850:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@850:  *
universe@850:  * Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
universe@850:  *
universe@850:  * Redistribution and use in source and binary forms, with or without
universe@850:  * modification, are permitted provided that the following conditions are met:
universe@850:  *
universe@850:  *   1. Redistributions of source code must retain the above copyright
universe@850:  *      notice, this list of conditions and the following disclaimer.
universe@850:  *
universe@850:  *   2. Redistributions in binary form must reproduce the above copyright
universe@850:  *      notice, this list of conditions and the following disclaimer in the
universe@850:  *      documentation and/or other materials provided with the distribution.
universe@850:  *
universe@850:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@850:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@850:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@850:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@850:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@850:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@850:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@850:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@850:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@850:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@850:  * POSSIBILITY OF SUCH DAMAGE.
universe@850:  */
universe@850: 
universe@850: #include "cx/iterator.h"
universe@850: 
universe@850: #include <string.h>
universe@850: 
universe@850: static bool cx_iter_valid(void const *it) {
universe@850:     struct cx_iterator_s const *iter = it;
universe@850:     return iter->index < iter->elem_count;
universe@850: }
universe@850: 
universe@850: static void *cx_iter_current(void const *it) {
universe@850:     struct cx_iterator_s const *iter = it;
universe@850:     return iter->elem_handle;
universe@850: }
universe@850: 
universe@850: static void cx_iter_next_fast(void *it) {
universe@850:     struct cx_iterator_base_s *itbase = it;
universe@850:     if (itbase->remove) {
universe@850:         struct cx_mut_iterator_s *iter = it;
universe@850:         itbase->remove = false;
universe@850:         iter->elem_count--;
universe@850:         // only move the last element when we are not currently aiming
universe@850:         // at the last element already
universe@850:         if (iter->index < iter->elem_count) {
universe@850:             void *last = ((char *) iter->src_handle)
universe@850:                          + iter->elem_count * iter->elem_size;
universe@850:             memcpy(iter->elem_handle, last, iter->elem_size);
universe@850:         }
universe@850:     } else {
universe@850:         struct cx_iterator_s *iter = it;
universe@850:         iter->index++;
universe@850:         iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
universe@850:     }
universe@850: }
universe@850: 
universe@850: static void cx_iter_next_slow(void *it) {
universe@850:     struct cx_iterator_base_s *itbase = it;
universe@850:     if (itbase->remove) {
universe@850:         struct cx_mut_iterator_s *iter = it;
universe@850:         itbase->remove = false;
universe@850:         iter->elem_count--;
universe@850: 
universe@850:         // number of elements to move
universe@850:         size_t remaining = iter->elem_count - iter->index;
universe@850:         if (remaining > 0) {
universe@850:             memmove(
universe@850:                     iter->elem_handle,
universe@850:                     ((char *) iter->elem_handle) + iter->elem_size,
universe@850:                     remaining * iter->elem_size
universe@850:             );
universe@850:         }
universe@850:     } else {
universe@850:         struct cx_iterator_s *iter = it;
universe@850:         iter->index++;
universe@850:         iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
universe@850:     }
universe@850: }
universe@850: 
universe@850: CxMutIterator cxIterator(
universe@850:         void *array,
universe@850:         size_t elem_size,
universe@850:         size_t elem_count,
universe@850:         bool remove_keeps_order
universe@850: ) {
universe@850:     CxMutIterator iter;
universe@850: 
universe@850:     iter.index = 0;
universe@850:     iter.src_handle = array;
universe@850:     iter.elem_handle = array;
universe@850:     iter.elem_size = elem_size;
universe@850:     iter.elem_count = array == NULL ? 0 : elem_count;
universe@850:     iter.base.valid = cx_iter_valid;
universe@850:     iter.base.current = cx_iter_current;
universe@850:     iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
universe@850:     iter.base.remove = false;
universe@850:     iter.base.mutating = true;
universe@850: 
universe@850:     return iter;
universe@850: }