rotate_forward.c

rotate_forward.c

#include <stdio.h>
#include <stdlib.h>

#   define stl_scope_begin do     {
#   define stl_scope_end   break; } while (0)

#   define stl_basic_swap(_Tp, __a, __b) \
    stl_scope_begin                      \
        _Tp __stl_c = (__a);             \
        (__a)       = (__b);             \
        (__b)       = __stl_c;           \
    stl_scope_end

#   define stl_rotate_forward(_Tp, __first, __n_first, __last, __result) \
    stl_scope_begin                                                      \
        _Tp * __stl_i;                                                   \
        if ((__first) == (__n_first)) {                                  \
            (__result) = (__last);                                       \
        } else if ((__n_first) == (__last)) {                            \
            (__result) = (__first);                                      \
        } else {                                                         \
            __stl_i = (__n_first);                                       \
            while (1) {                                                  \
                stl_basic_swap(_Tp, *(__first), *__stl_i);               \
                ++(__first);                                             \
                if (++__stl_i == __last) {                               \
                    break;                                               \
                }                                                        \
                if ((__first) == (__n_first)) {                          \
                    (__n_first) = __stl_i;                               \
                }                                                        \
            }                                                            \
            (__result) = (__first);                                      \
            if ((__first) != (__n_first)) {                              \
                __stl_i = (__n_first);                                   \
                while (1) {                                              \
                    stl_basic_swap(_Tp, *(__first), *__stl_i);           \
                    ++(__first);                                         \
                    if (++__stl_i == __last) {                           \
                        if ((__first) == (__n_first)) {                  \
                            break;                                       \
                        }                                                \
                        __stl_i = (__n_first);                           \
                    } else if ((__first) == (__n_first)) {               \
                        (__n_first) = __stl_i;                           \
                    }                                                    \
                }                                                        \
            }                                                            \
        }                                                                \
    stl_scope_end

int main(int argc, const char ** argv)
{
    int vec1[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
    int vec2[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    int * vec1_begin = vec1;
    int * vec1_rotl  = vec1 + 3;
    int * vec1_end   = vec1 + 9;
    int * vec1_result;

    int * vec2_begin = vec2;
    int * vec2_rotr  = vec2 + 9 - 4;
    int * vec2_end   = vec2 + 9;
    int * vec2_result;

    fprintf(stderr, "initial vector1 :\n[ ");
    for (int i = 0; i < 9; i++) {
        fprintf(stderr, "%d ", vec1[i]);
    }
    fprintf(stderr, "]\n");

    stl_rotate_forward(int
        , vec1_begin
        , vec1_rotl
        , vec1_end
        , vec1_result
    );

    fprintf(stderr, "after left rotation :\n[ ");
    for (int i = 0; i < 9; i++) {
        fprintf(stderr, "%d ", vec1[i]);
    }
    fprintf(stderr, "]\n");

    fprintf(stderr, "left rotation result:\n[ ");
    while (vec1_result != vec1_end) {
        fprintf(stderr, "%d ", *vec1_result);
        ++vec1_result;
    }
    fprintf(stderr, "]\n");

    fprintf(stderr, "\ninitial vector2 :\n[ ");
    for (int i = 0; i < 9; i++) {
        fprintf(stderr, "%d ", vec2[i]);
    }
    fprintf(stderr, "]\n");

    stl_rotate_forward(int
        , vec2_begin
        , vec2_rotr
        , vec2_end
        , vec2_result
    );

    fprintf(stderr, "after right rotation :\n[ ");
    for (int i = 0; i < 9; i++) {
        fprintf(stderr, "%d ", vec2[i]);
    }
    fprintf(stderr, "]\n");

    fprintf(stderr, "right rotation result:\n[ ");
    while (vec2_result != vec2_end) {
        fprintf(stderr, "%d ", *vec2_result);
        ++vec2_result;
    }
    fprintf(stderr, "]\n");
    
    return 0;
}

/* EOF */