Function sz_string_expand

include/stringzilla/small_string.h:397–436

}

SZ_PUBLIC sz_ptr_t sz_string_expand( //
    sz_string_t *string, sz_size_t offset, sz_size_t added_length, sz_memory_allocator_t *allocator) {

    sz_assert_(string && allocator && "String and allocator can't be SZ_NULL.");

    sz_ptr_t string_start;
    sz_size_t string_length;
    sz_size_t string_space;
    sz_bool_t string_is_external;
    sz_string_unpack(string, &string_start, &string_length, &string_space, &string_is_external);

    // The user intended to extend the string.
    offset = sz_min_of_two(offset, string_length);

    // Guard against integer overflow in size calculation.
    if (added_length > SZ_SSIZE_MAX - string_length - 1) return SZ_NULL_CHAR;

    // If we are lucky, no memory allocations will be needed.
    if (string_length + added_length < string_space) {
        sz_move(string_start + offset + added_length, string_start + offset, string_length - offset);
        string_start[string_length + added_length] = 0;
        // Even if the string is on the stack, the `+=` won't affect the tail of the string.
        string->external.length += added_length;
    }
    // If we are not lucky, we need to allocate more memory.
    else {
        sz_size_t next_planned_size = sz_max_of_two(SZ_CACHE_LINE_WIDTH, string_space * (sz_size_t)2);
        sz_size_t min_needed_space = sz_size_bit_ceil(offset + string_length + added_length + 1);
        sz_size_t new_space = sz_max_of_two(min_needed_space, next_planned_size);
        string_start = sz_string_reserve(string, new_space - 1, allocator);
        if (!string_start) return SZ_NULL_CHAR;

        // Copy into the new buffer.
        sz_move(string_start + offset + added_length, string_start + offset, string_length - offset);
        string_start[string_length + added_length] = 0;
        string->external.length = string_length + added_length;
    }

    return string_start;
}

SZ_PUBLIC sz_size_t sz_string_erase(sz_string_t *string, sz_size_t offset, sz_size_t length) {