method

rotate

v1_9_2_180 - Show latest stable - Class: Array

rotate(p1 = v1)

public

Returns new array by rotating self, whose first element is the element at cnt in self. If cnt is negative then it rotates in counter direction.

a = [ "a", "b", "c", "d" ]
a.rotate         #=> ["b", "c", "d", "a"]
a                #=> ["a", "b", "c", "d"]
a.rotate(2)      #=> ["c", "d", "a", "b"]
a.rotate(-3)     #=> ["b", "c", "d", "a"]

static VALUE
rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE rotated, *ptr, *ptr2;
    long len, cnt = 1;

    switch (argc) {
      case 1: cnt = NUM2LONG(argv[0]);
      case 0: break;
      default: rb_scan_args(argc, argv, "01", NULL);
    }

    len = RARRAY_LEN(ary);
    rotated = rb_ary_dup_setup(ary);
    if (len > 0) {
        cnt = rotate_count(cnt, len);
        ptr = RARRAY_PTR(ary);
        ptr2 = RARRAY_PTR(rotated);
        len -= cnt;
        MEMCPY(ptr2, ptr + cnt, VALUE, len);
        MEMCPY(ptr2 + len, ptr, VALUE, cnt);
    }
    return rotated;
}

rotate

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