src/array_list.c

/*
 * 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/array_list.h"
#include <assert.h>
#include <string.h>
#include <stdint.h>

// LOW LEVEL ARRAY LIST FUNCTIONS

enum cx_array_copy_result cx_array_copy(
        void **target,
        size_t *size,
        size_t *capacity,
        size_t index,
        void const *src,
        size_t elem_size,
        size_t elem_count,
        struct cx_array_reallocator_s *reallocator
) {
    // assert pointers
    assert(target != NULL);
    assert(size != NULL);
    assert(src != NULL);

    // determine capacity
    size_t cap = capacity == NULL ? *size : *capacity;

    // check if resize is required
    size_t minsize = index + elem_count;
    size_t newsize = *size < minsize ? minsize : *size;
    bool needrealloc = newsize > cap;

    // reallocate if possible
    if (needrealloc) {
        // a reallocator and a capacity variable must be available
        if (reallocator == NULL || capacity == NULL) {
            return CX_ARRAY_COPY_REALLOC_NOT_SUPPORTED;
        }

        // check, if we need to repair the src pointer
        uintptr_t targetaddr = (uintptr_t) *target;
        uintptr_t srcaddr = (uintptr_t) src;
        bool repairsrc = targetaddr <= srcaddr
                         && srcaddr < targetaddr + cap * elem_size;

        // calculate new capacity (next number divisible by 16)
        cap = newsize - (newsize % 16) + 16;
        assert(cap > newsize);

        // perform reallocation
        void *newmem = reallocator->realloc(
                *target, cap, elem_size, reallocator
        );
        if (newmem == NULL) {
            return CX_ARRAY_COPY_REALLOC_FAILED;
        }

        // repair src pointer, if necessary
        if (repairsrc) {
            src = ((char *) newmem) + (srcaddr - targetaddr);
        }

        // store new pointer and capacity
        *target = newmem;
        *capacity = cap;
    }

    // determine target pointer
    char *start = *target;
    start += index * elem_size;

    // copy elements and set new size
    memmove(start, src, elem_count * elem_size);
    *size = newsize;

    // return successfully
    return CX_ARRAY_COPY_SUCCESS;
}

#define CX_ARRAY_SWAP_SBO_SIZE 512

void cx_array_swap(
        void *arr,
        size_t elem_size,
        size_t idx1,
        size_t idx2
) {
    // short circuit
    if (idx1 == idx2) return;

    char sbo_mem[CX_ARRAY_SWAP_SBO_SIZE];
    void *tmp;

    // decide if we can use the local buffer
    if (elem_size > CX_ARRAY_SWAP_SBO_SIZE) {
        tmp = malloc(elem_size);
        // we don't want to enforce error handling
        if (tmp == NULL) abort();
    } else {
        tmp = sbo_mem;
    }

    // calculate memory locations
    char *left = arr, *right = arr;
    left += idx1 * elem_size;
    right += idx2 * elem_size;

    // three-way swap
    memcpy(tmp, left, elem_size);
    memcpy(left, right, elem_size);
    memcpy(right, tmp, elem_size);

    // free dynamic memory, if it was needed
    if (tmp != sbo_mem) {
        free(tmp);
    }
}

// HIGH LEVEL ARRAY LIST FUNCTIONS

typedef struct {
    struct cx_list_s base;
    void *data;
    struct cx_array_reallocator_s reallocator;
} cx_array_list;

static void *cx_arl_realloc(
        void *array,
        size_t capacity,
        size_t elem_size,
        struct cx_array_reallocator_s *alloc
) {
    // retrieve the pointer to the list allocator
    CxAllocator const *al = alloc->ptr1;

    // use the list allocator to reallocate the memory
    return cxRealloc(al, array, capacity * elem_size);
}

static void cx_arl_destructor(struct cx_list_s *list) {
    cx_array_list *arl = (cx_array_list *) list;
    cxFree(list->allocator, arl->data);
}

static int cx_arl_add(
        struct cx_list_s *list,
        void const *elem
) {
    cx_array_list *arl = (cx_array_list *) list;
    return cx_array_copy(
            &arl->data,
            &list->size,
            &list->capacity,
            list->size,
            elem,
            list->itemsize,
            1,
            &arl->reallocator
    );
}

static size_t cx_arl_insert_array(
        struct cx_list_s *list,
        size_t index,
        void const *array,
        size_t n
) {
    // out of bounds and special case check
    if (index > list->size || n == 0) return 0;

    // get a correctly typed pointer to the list
    cx_array_list *arl = (cx_array_list *) list;

    // do we need to move some elements?
    if (index < list->size) {
        char const *first_to_move = (char const *) arl->data;
        first_to_move += index * list->itemsize;
        size_t elems_to_move = list->size - index;
        size_t start_of_moved = index + n;

        if (CX_ARRAY_COPY_SUCCESS != cx_array_copy(
                &arl->data,
                &list->size,
                &list->capacity,
                start_of_moved,
                first_to_move,
                list->itemsize,
                elems_to_move,
                &arl->reallocator
        )) {
            // if moving existing elems is unsuccessful, abort
            return 0;
        }
    }

    // note that if we had to move the elements, the following operation
    // is guaranteed to succeed, because we have the memory already allocated
    // therefore, it is impossible to leave this function with an invalid array

    // place the new elements
    if (CX_ARRAY_COPY_SUCCESS == cx_array_copy(
            &arl->data,
            &list->size,
            &list->capacity,
            index,
            array,
            list->itemsize,
            n,
            &arl->reallocator
    )) {
        return n;
    } else {
        // array list implementation is "all or nothing"
        return 0;
    }
}

static size_t cx_arl_add_array(
        struct cx_list_s *list,
        void const *array,
        size_t n
) {
    return cx_arl_insert_array(list, list->size, array, n);
}

static int cx_arl_insert(
        struct cx_list_s *list,
        size_t index,
        void const *elem
) {
    if (index > list->size) {
        return 1;
    } else if (index == list->size) {
        return cx_arl_add(list, elem);
    } else {
        cx_array_list *arl = (cx_array_list *) list;

        // move elements starting at index to the right
        if (cx_array_copy(
                &arl->data,
                &list->size,
                &list->capacity,
                index + 1,
                ((char *) arl->data) + index * list->itemsize,
                list->itemsize,
                list->size - index,
                &arl->reallocator
        )) {
            return 1;
        }

        // place the element
        memcpy(((char *) arl->data) + index * list->itemsize,
               elem, list->itemsize);

        return 0;
    }
}

static int cx_arl_insert_iter(
        struct cx_mut_iterator_s *iter,
        void const *elem,
        int prepend
) {
    struct cx_list_s *list = iter->src_handle;
    if (iter->index < list->size) {
        int result = cx_arl_insert(
                list,
                iter->index + 1 - prepend,
                elem
        );
        if (result == 0 && prepend != 0) {
            iter->index++;
            iter->elem_handle = ((char *) iter->elem_handle) + list->itemsize;
        }
        return result;
    } else {
        int result = cx_arl_add(list, elem);
        iter->index = list->size;
        return result;
    }
}

static int cx_arl_remove(
        struct cx_list_s *list,
        size_t index
) {
    // out-of-bounds check
    if (index >= list->size) {
        return 1;
    }

    // short-circuit removal of last element
    if (index == list->size - 1) {
        list->size--;
        return 0;
    }

    // just move the elements starting at index to the left
    cx_array_list *arl = (cx_array_list *) list;
    int result = cx_array_copy(
            &arl->data,
            &list->size,
            &list->capacity,
            index,
            ((char *) arl->data) + (index + 1) * list->itemsize,
            list->itemsize,
            list->size - index - 1,
            &arl->reallocator
    );
    if (result == 0) {
        // decrease the size
        list->size--;
    }
    return result;
}

static void *cx_arl_at(
        struct cx_list_s const *list,
        size_t index
) {
    if (index < list->size) {
        cx_array_list const *arl = (cx_array_list const *) list;
        char *space = arl->data;
        return space + index * list->itemsize;
    } else {
        return NULL;
    }
}

static size_t cx_arl_find(
        struct cx_list_s const *list,
        void const *elem
) {
    char *cur = ((cx_array_list const *) list)->data;

    for (size_t i = 0; i < list->size; i++) {
        if (0 == list->cmpfunc(elem, cur)) {
            return i;
        }
        cur += list->itemsize;
    }

    return list->size;
}

static void cx_arl_sort(struct cx_list_s *list) {
    qsort(((cx_array_list *) list)->data,
          list->size,
          list->itemsize,
          list->cmpfunc
    );
}

static int cx_arl_compare(
        struct cx_list_s const *list,
        struct cx_list_s const *other
) {
    if (list->size == other->size) {
        char const *left = ((cx_array_list const *) list)->data;
        char const *right = ((cx_array_list const *) other)->data;
        for (size_t i = 0; i < list->size; i++) {
            int d = list->cmpfunc(left, right);
            if (d != 0) {
                return d;
            }
            left += list->itemsize;
            right += other->itemsize;
        }
        return 0;
    } else {
        return list->size < other->size ? -1 : 1;
    }
}

static void cx_arl_reverse(struct cx_list_s *list) {
    if (list->size < 2) return;
    void *data = ((cx_array_list const *) list)->data;
    size_t half = list->size / 2;
    for (size_t i = 0; i < half; i++) {
        cx_array_swap(data, list->itemsize, i, list->size - 1 - i);
    }
}

static bool cx_arl_iter_valid(void const *it) {
    struct cx_iterator_s const *iter = it;
    struct cx_list_s const *list = iter->src_handle;
    return iter->index < list->size;
}

static void *cx_arl_iter_current(void const *it) {
    struct cx_iterator_s const *iter = it;
    return iter->elem_handle;
}

static void cx_arl_iter_next(void *it) {
    struct cx_iterator_base_s *itbase = it;
    if (itbase->remove) {
        struct cx_mut_iterator_s *iter = it;
        itbase->remove = false;
        cx_arl_remove(iter->src_handle, iter->index);
    } else {
        struct cx_iterator_s *iter = it;
        iter->index++;
        iter->elem_handle =
                ((char *) iter->elem_handle)
                + ((struct cx_list_s const *) iter->src_handle)->itemsize;
    }
}

static bool cx_arl_iter_flag_rm(void *it) {
    struct cx_iterator_base_s *iter = it;
    if (iter->mutating) {
        iter->remove = true;
        return true;
    } else {
        return false;
    }
}

static struct cx_iterator_s cx_arl_iterator(
        struct cx_list_s const *list,
        size_t index
) {
    struct cx_iterator_s iter;

    iter.index = index;
    iter.src_handle = list;
    iter.elem_handle = cx_arl_at(list, index);
    iter.base.valid = cx_arl_iter_valid;
    iter.base.current = cx_arl_iter_current;
    iter.base.next = cx_arl_iter_next;
    iter.base.flag_removal = cx_arl_iter_flag_rm;
    iter.base.remove = false;
    iter.base.mutating = false;

    return iter;
}

static struct cx_mut_iterator_s cx_arl_mut_iterator(
        struct cx_list_s *list,
        size_t index
) {
    CxIterator it = cx_arl_iterator(list, index);
    it.base.mutating = true;

    // we know the iterators share the same memory layout
    CxMutIterator iter;
    memcpy(&iter, &it, sizeof(CxMutIterator));
    return iter;
}

static cx_list_class cx_array_list_class = {
        cx_arl_destructor,
        cx_arl_add,
        cx_arl_add_array,
        cx_arl_insert,
        cx_arl_insert_array,
        cx_arl_insert_iter,
        cx_arl_remove,
        cx_arl_at,
        cx_arl_find,
        cx_arl_sort,
        cx_arl_compare,
        cx_arl_reverse,
        cx_arl_iterator,
        cx_arl_mut_iterator,
};

CxList *cxArrayListCreate(
        CxAllocator const *allocator,
        CxListComparator comparator,
        size_t item_size,
        size_t initial_capacity
) {
    cx_array_list *list = cxCalloc(allocator, 1, sizeof(cx_array_list));
    if (list == NULL) return NULL;

    list->data = cxCalloc(allocator, initial_capacity, item_size);
    if (list->data == NULL) {
        cxFree(allocator, list);
        return NULL;
    }

    list->base.cl = &cx_array_list_class;
    list->base.allocator = allocator;
    list->base.cmpfunc = comparator;
    list->base.itemsize = item_size;
    list->base.capacity = initial_capacity;

    // configure the reallocator
    list->reallocator.realloc = cx_arl_realloc;
    list->reallocator.ptr1 = (void *) allocator;

    return (CxList *) list;
}