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/*
 * 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.
 */
/**
 * \file array_list.h
 * \brief Array list implementation.
 * \details Also provides several low-level functions for custom array list implementations.
 * \author Mike Becker
 * \author Olaf Wintermann
 * \copyright 2-Clause BSD License
 */


#ifndef UCX_ARRAY_LIST_H
#define UCX_ARRAY_LIST_H

#include "list.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * The maximum item size in an array list that fits into stack buffer when swapped.
 */
extern const unsigned cx_array_swap_sbo_size;

/**
 * Declares variables for an array that can be used with the convenience macros.
 *
 * @see cx_array_simple_add()
 * @see cx_array_simple_copy()
 * @see cx_array_initialize()
 * @see cx_array_simple_add_sorted()
 * @see cx_array_simple_insert_sorted()
 */
#define CX_ARRAY_DECLARE(type, name) \
    type * name;                     \
    size_t name##_size;              \
    size_t name##_capacity

/**
 * Initializes an array declared with CX_ARRAY_DECLARE().
 *
 * The memory for the array is allocated with stdlib malloc().
 * @param array the array
 * @param capacity the initial capacity
 */
#define cx_array_initialize(array, capacity) \
        array##_capacity = capacity; \
        array##_size = 0; \
        array = malloc(sizeof(array[0]) * capacity)

/**
 * Defines a reallocation mechanism for arrays.
 */
struct cx_array_reallocator_s {
    /**
     * Reallocates space for the given array.
     *
     * Implementations are not required to free the original array.
     * This allows reallocation of static memory by allocating heap memory
     * and copying the array contents. The information in the custom fields of
     * the referenced allocator can be used to track the state of the memory
     * or to transport other additional data.
     *
     * @param array the array to reallocate
     * @param capacity the new capacity (number of elements)
     * @param elem_size the size of each element
     * @param alloc a reference to this allocator
     * @return a pointer to the reallocated memory or \c NULL on failure
     */
    void *(*realloc)(
            void *array,
            size_t capacity,
            size_t elem_size,
            struct cx_array_reallocator_s *alloc
    );

    /**
     * Custom data pointer.
     */
    void *ptr1;
    /**
     * Custom data pointer.
     */
    void *ptr2;
    /**
     * Custom data integer.
     */
    size_t int1;
    /**
     * Custom data integer.
     */
    size_t int2;
};

/**
 * Typedef for the array reallocator struct.
 */
typedef struct cx_array_reallocator_s CxArrayReallocator;

/**
 * A default stdlib-based array reallocator.
 */
extern struct cx_array_reallocator_s *cx_array_default_reallocator;

/**
 * Creates a new array reallocator.
 *
 * When \p allocator is \c NULL, the stdlib default allocator will be used.
 *
 * When \p stackmem is not \c NULL, the reallocator is supposed to be used
 * \em only for the specific array that is initially located at \p stackmem.
 * When reallocation is needed, the reallocator checks, if the array is
 * still located at \p stackmem and copies the contents to the heap.
 *
 * @param allocator the allocator this reallocator shall be based on
 * @param stackmem the address of the array when the array is initially located
 * on the stack
 * @return an array reallocator
 */
struct cx_array_reallocator_s cx_array_reallocator(
        const struct cx_allocator_s *allocator,
        const void *stackmem
);

/**
 * Return codes for array functions.
 */
enum cx_array_result {
    CX_ARRAY_SUCCESS,
    CX_ARRAY_REALLOC_NOT_SUPPORTED,
    CX_ARRAY_REALLOC_FAILED,
};

/**
 * Copies elements from one array to another.
 *
 * The elements are copied to the \p target array at the specified \p index,
 * overwriting possible elements. The \p index does not need to be in range of
 * the current array \p size. If the new index plus the number of elements added
 * would extend the array's size, and \p capacity is not \c NULL, the remaining
 * capacity is used.
 *
 * If the capacity is insufficient to hold the new data, a reallocation
 * attempt is made, unless the \p reallocator is set to \c NULL, in which case
 * this function ultimately returns a failure.
 *
 * @param target a pointer to the target array
 * @param size a pointer to the size of the target array
 * @param capacity a pointer to the target array's capacity -
 * \c NULL if only the size shall be used to bound the array (reallocations
 * will NOT be supported in that case)
 * @param index the index where the copied elements shall be placed
 * @param src the source array
 * @param elem_size the size of one element
 * @param elem_count the number of elements to copy
 * @param reallocator the array reallocator to use, or \c NULL
 * if reallocation shall not happen
 * @return zero on success, non-zero error code on failure
 */
__attribute__((__nonnull__(1, 2, 5)))
enum cx_array_result cx_array_copy(
        void **target,
        size_t *size,
        size_t *capacity,
        size_t index,
        const void *src,
        size_t elem_size,
        size_t elem_count,
        struct cx_array_reallocator_s *reallocator
);

/**
 * Convenience macro that uses cx_array_copy() with a default layout and the default reallocator.
 *
 * @param array the name of the array (NOT a pointer to the array)
 * @param index the index where the copied elements shall be placed
 * @param src the source array
 * @param count the number of elements to copy
 * @see CX_ARRAY_DECLARE()
 */
#define cx_array_simple_copy(array, index, src, count) \
    cx_array_copy((void**)&(array), &(array##_size), &(array##_capacity), \
    index, src, sizeof((array)[0]), count, cx_array_default_reallocator)

/**
 * Adds an element to an array with the possibility of allocating more space.
 *
 * The element \p elem is added to the end of the \p target array which containing
 * \p size elements, already. The \p capacity must not be \c NULL and point a
 * variable holding the current maximum number of elements the array can hold.
 *
 * If the capacity is insufficient to hold the new element, and the optional
 * \p reallocator is not \c NULL, an attempt increase the \p capacity is made
 * and the new capacity is written back.
 *
 * @param target a pointer to the target array
 * @param size a pointer to the size of the target array
 * @param capacity a pointer to the target array's capacity - must not be \c NULL
 * @param elem_size the size of one element
 * @param elem a pointer to the element to add
 * @param reallocator the array reallocator to use, or \c NULL if reallocation shall not happen
 * @return zero on success, non-zero error code on failure
 */
#define cx_array_add(target, size, capacity, elem_size, elem, reallocator) \
    cx_array_copy((void**)(target), size, capacity, *(size), elem, elem_size, 1, reallocator)

/**
 * Convenience macro that uses cx_array_add() with a default layout and
 * the default reallocator.
 *
 * @param array the name of the array (NOT a pointer to the array)
 * @param elem the element to add (NOT a pointer, address is automatically taken)
 * @see CX_ARRAY_DECLARE()
 */
#define cx_array_simple_add(array, elem) \
    cx_array_simple_copy(array, array##_size, &(elem), 1)


/**
 * Inserts a sorted array into another sorted array.
 *
 * If either the target or the source array is not already sorted with respect
 * to the specified \p cmp_func, the behavior is undefined.
 *
 * If the capacity is insufficient to hold the new data, a reallocation
 * attempt is made.
 *
 * @param target a pointer to the target array
 * @param size a pointer to the size of the target array
 * @param capacity a pointer to the target array's capacity
 * @param cmp_func the compare function for the elements
 * @param src the source array
 * @param elem_size the size of one element
 * @param elem_count the number of elements to insert
 * @param reallocator the array reallocator to use
 * @return zero on success, non-zero error code on failure
 */
__attribute__((__nonnull__))
enum cx_array_result cx_array_insert_sorted(
        void **target,
        size_t *size,
        size_t *capacity,
        cx_compare_func cmp_func,
        const void *src,
        size_t elem_size,
        size_t elem_count,
        struct cx_array_reallocator_s *reallocator
);

/**
 * Inserts an element into a sorted array.
 *
 * If the target array is not already sorted with respect
 * to the specified \p cmp_func, the behavior is undefined.
 *
 * If the capacity is insufficient to hold the new data, a reallocation
 * attempt is made.
 *
 * @param target a pointer to the target array
 * @param size a pointer to the size of the target array
 * @param capacity a pointer to the target array's capacity
 * @param elem_size the size of one element
 * @param elem a pointer to the element to add
 * @param reallocator the array reallocator to use
 * @return zero on success, non-zero error code on failure
 */
#define cx_array_add_sorted(target, size, capacity, elem_size, elem, cmp_func, reallocator) \
    cx_array_insert_sorted((void**)(target), size, capacity, cmp_func, elem, elem_size, 1, reallocator)

/**
 * Convenience macro for cx_array_add_sorted() with a default
 * layout and the default reallocator.
 *
 * @param array the name of the array (NOT a pointer to the array)
 * @param elem the element to add (NOT a pointer, address is automatically taken)
 * @param cmp_func the compare function for the elements
 * @see CX_ARRAY_DECLARE()
 */
#define cx_array_simple_add_sorted(array, elem, cmp_func) \
    cx_array_add_sorted(&array, &(array##_size), &(array##_capacity), \
        sizeof((array)[0]), &(elem), cmp_func, cx_array_default_reallocator)

/**
 * Convenience macro for cx_array_insert_sorted() with a default
 * layout and the default reallocator.
 *
 * @param array the name of the array (NOT a pointer to the array)
 * @param src pointer to the source array
 * @param n number of elements in the source array
 * @param cmp_func the compare function for the elements
 * @see CX_ARRAY_DECLARE()
 */
#define cx_array_simple_insert_sorted(array, src, n, cmp_func) \
    cx_array_insert_sorted((void**)(&array), &(array##_size), &(array##_capacity), \
        cmp_func, src, sizeof((array)[0]), n, cx_array_default_reallocator)


/**
 * Searches the largest lower bound in a sorted array.
 *
 * In other words, this function returns the index of the largest element
 * in \p arr that is less or equal to \p elem with respect to \p cmp_func.
 * When no such element exists, \p size is returned.
 *
 * If \p elem is contained in the array, this is identical to
 * #cx_array_binary_search().
 *
 * If the array is not sorted with respect to the \p cmp_func, the behavior
 * is undefined.
 *
 * @param arr the array to search
 * @param size the size of the array
 * @param elem_size the size of one element
 * @param elem the element to find
 * @param cmp_func the compare function
 * @return the index of the largest lower bound, or \p size
 */
__attribute__((__nonnull__))
size_t cx_array_binary_search_inf(
        const void *arr,
        size_t size,
        size_t elem_size,
        const void *elem,
        cx_compare_func cmp_func
);

/**
 * Searches an item in a sorted array.
 *
 * If the array is not sorted with respect to the \p cmp_func, the behavior
 * is undefined.
 *
 * @param arr the array to search
 * @param size the size of the array
 * @param elem_size the size of one element
 * @param elem the element to find
 * @param cmp_func the compare function
 * @return the index of the element in the array, or \p size if the element
 * cannot be found
 */
__attribute__((__nonnull__))
static inline size_t cx_array_binary_search(
        const void *arr,
        size_t size,
        size_t elem_size,
        const void *elem,
        cx_compare_func cmp_func
) {
    size_t index = cx_array_binary_search_inf(
            arr, size, elem_size, elem, cmp_func
    );
    if (index < size && cmp_func(((const char *) arr) + index * elem_size, elem) == 0) {
        return index;
    } else {
        return size;
    }
}

/**
 * Searches the smallest upper bound in a sorted array.
 *
 * In other words, this function returns the index of the smallest element
 * in \p arr that is greater or equal to \p elem with respect to \p cmp_func.
 * When no such element exists, \p size is returned.
 *
 * If \p elem is contained in the array, this is identical to
 * #cx_array_binary_search().
 *
 * If the array is not sorted with respect to the \p cmp_func, the behavior
 * is undefined.
 *
 * @param arr the array to search
 * @param size the size of the array
 * @param elem_size the size of one element
 * @param elem the element to find
 * @param cmp_func the compare function
 * @return the index of the smallest upper bound, or \p size
 */
__attribute__((__nonnull__))
static inline size_t cx_array_binary_search_sup(
        const void *arr,
        size_t size,
        size_t elem_size,
        const void *elem,
        cx_compare_func cmp_func
) {
    size_t inf = cx_array_binary_search_inf(arr, size, elem_size, elem, cmp_func);
    if (inf == size) {
        // no infimum means, first element is supremum
        return 0;
    } else if (cmp_func(((const char *) arr) + inf * elem_size, elem) == 0) {
        return inf;
    } else {
        return inf + 1;
    }
}

/**
 * Swaps two array elements.
 *
 * @param arr the array
 * @param elem_size the element size
 * @param idx1 index of first element
 * @param idx2 index of second element
 */
__attribute__((__nonnull__))
void cx_array_swap(
        void *arr,
        size_t elem_size,
        size_t idx1,
        size_t idx2
);

/**
 * Allocates an array list for storing elements with \p elem_size bytes each.
 *
 * If \p elem_size is CX_STORE_POINTERS, the created list will be created as if
 * cxListStorePointers() was called immediately after creation and the compare
 * function will be automatically set to cx_cmp_ptr(), if none is given.
 *
 * @param allocator the allocator for allocating the list memory
 * (if \c NULL the cxDefaultAllocator will be used)
 * @param comparator the comparator for the elements
 * (if \c NULL, and the list is not storing pointers, sort and find
 * functions will not work)
 * @param elem_size the size of each element in bytes
 * @param initial_capacity the initial number of elements the array can store
 * @return the created list
 */
CxList *cxArrayListCreate(
        const CxAllocator *allocator,
        cx_compare_func comparator,
        size_t elem_size,
        size_t initial_capacity
);

/**
 * Allocates an array list for storing elements with \p elem_size bytes each.
 *
 * The list will use the cxDefaultAllocator and \em NO compare function.
 * If you want to call functions that need a compare function, you have to
 * set it immediately after creation or use cxArrayListCreate().
 *
 * If \p elem_size is CX_STORE_POINTERS, the created list will be created as if
 * cxListStorePointers() was called immediately after creation and the compare
 * function will be automatically set to cx_cmp_ptr().
 *
 * @param elem_size the size of each element in bytes
 * @param initial_capacity the initial number of elements the array can store
 * @return the created list
 */
#define cxArrayListCreateSimple(elem_size, initial_capacity) \
    cxArrayListCreate(NULL, NULL, elem_size, initial_capacity)

#ifdef __cplusplus
} // extern "C"
#endif

#endif // UCX_ARRAY_LIST_H