[boost] Submission: Fixed-Capacity STL Containers Library (Re: STLcontainer of fixed capacity but va

From: Alisdair Meredith (alisdair.meredith_at_[hidden])
Date: 2002-02-06 04:48:12

OK, finally found time to download the source :* )  [Confession:  it has taken a while to get Yahoo groups working correctly]

Having recently read Herb Sutter's 'Exceptional C++'  I was keen to take a look at the swap specialization, as I was not sure how this would work.  Neat, I discover a new std algorithm for just these occasions!  However...

  template <std::size_t N2>
  void swap(fixed_capacity_vector<T, N2>& x) {
    if (size() > N2 || x.size() > N)
      throw std::range_error("fixed_capacity_vector");
    if (size() <= x.size()) {
      size_type d = x.size() - size();
      std::swap_ranges(begin(), end(), x.begin());
      insert(end(), x.begin() + size(), x.end());
      x.erase(x.end() - d, x.end());
    } else {
      size_type d = size() - x.size();
      std::swap_ranges(x.begin(), x.end(), begin());
      x.insert(x.end(), begin() + x.size(), end());
      erase(end() - d, end());
    }
  }

I believe both calls to insert can fail on copy-constructors, and leave you with a modified container [so breaking the exception guarantees]

Not sure how to fix this [or if it is fixable] but it should at least be documented.  I expect [no timing tests done] that this also means swapping fixed_vectors should be significantly slower than std::vectors.  Given the relative infrequency of swapping the containers, the tradoff is likely worthwhile, but again worth noting [after measurements!]

AlisdairM

>>> wistaria_at_[hidden] 5 February 2002 12:57:31 >>>

I've just uploaded my new version of fixed_capacity_vector and others:

  http://groups.yahoo.com/group/boost/files/fixed_capacity/ 

...

Any comments/suggestions are welcome.

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