ceph/src/boost/libs/container/example/doc_custom_vector.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2013-2013. Distributed under the Boost
   4 // Software License, Version 1.0. (See accompanying file
   5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org/libs/container for documentation.
   8 //
   9 //////////////////////////////////////////////////////////////////////////////
  10 //[doc_custom_vector
  11 #include <boost/container/vector.hpp>
  12 #include <boost/static_assert.hpp>
  13
  14 //Make sure assertions are active
  15 #ifdef NDEBUG
  16 #undef NDEBUG
  17 #endif
  18 #include <cassert>
  19
  20 int main ()
  21 {
  22    using namespace boost::container;
  23
  24    //This option specifies that a vector that will use "unsigned char" as
  25    //the type to store capacity or size internally.
  26    typedef vector_options< stored_size<unsigned char> >::type size_option_t;
  27
  28    //Size-optimized vector is smaller than the default one.
  29    typedef vector<int, new_allocator<int>, size_option_t > size_optimized_vector_t;
  30    BOOST_STATIC_ASSERT(( sizeof(size_optimized_vector_t) < sizeof(vector<int>) ));
  31
  32    //Requesting capacity for more elements than representable by "unsigned char"
  33    //is an error in the size optimized vector.
  34    bool exception_thrown = false;
  35    try       { size_optimized_vector_t v(256); }
  36    catch(...){ exception_thrown = true;        }
  37    assert(exception_thrown == true);
  38
  39    //This option specifies that a vector will increase its capacity 50%
  40    //each time the previous capacity was exhausted.
  41    typedef vector_options< growth_factor<growth_factor_50> >::type growth_50_option_t;
  42
  43    //Fill the vector until full capacity is reached
  44    vector<int, new_allocator<int>, growth_50_option_t > growth_50_vector(5, 0);
  45    const std::size_t old_cap = growth_50_vector.capacity();
  46    growth_50_vector.resize(old_cap);
  47
  48    //Now insert an additional item and check the new buffer is 50% bigger
  49    growth_50_vector.push_back(1);
  50    assert(growth_50_vector.capacity() == old_cap*3/2);
  51
  52    return 0;
  53 }
  54 //]