Default initialization for vector-like containers

Complexity guarantees for associative container constructors and ordered input ranges
Added benchmark for associative containers
Fixes #9166

[SVN r85964]

test/vector_test.hpp

@@ -31,12 +31,130 @@
 #include <boost/move/utility.hpp>
 #include <boost/move/iterator.hpp>
 #include <boost/detail/no_exceptions_support.hpp>
+#include <boost/static_assert.hpp>
 #include "insert_test.hpp"
 
 namespace boost{
 namespace container {
 namespace test{
 
+//
+template<int Dummy = 0>
+class default_init_allocator_base
+{
+   protected:
+   static unsigned char s_pattern;
+   static bool          s_ascending;
+
+   public:
+   static void reset_pattern(unsigned char value)
+   {  s_pattern = value;   }
+
+   static void set_ascending(bool enable)
+   {  s_ascending = enable;   }
+};
+
+template<int Dummy>
+unsigned char default_init_allocator_base<Dummy>::s_pattern = 0u;
+
+template<int Dummy>
+bool default_init_allocator_base<Dummy>::s_ascending = true;
+
+template<class T>
+class default_init_allocator
+   : public default_init_allocator_base<0>
+{
+   typedef default_init_allocator_base<0> base_t;
+   public:
+   typedef T value_type;
+
+   default_init_allocator()
+   {}
+
+   template <class U>
+   default_init_allocator(default_init_allocator<U>)
+   {}
+
+   T* allocate(std::size_t n)
+   {
+      //Initialize memory to a pattern
+      T *const p = ::new T[n];
+      unsigned char *puc_raw = reinterpret_cast<unsigned char*>(p);
+      std::size_t max = sizeof(T)*n;
+      if(base_t::s_ascending){
+         for(std::size_t i = 0; i != max; ++i){
+            puc_raw[i] = static_cast<unsigned char>(s_pattern++);
+         }
+      }
+      else{
+         for(std::size_t i = 0; i != max; ++i){
+            puc_raw[i] = static_cast<unsigned char>(s_pattern--);
+         }
+      }
+      return p;
+   }
+
+   void deallocate(T *p, std::size_t)
+   {  delete[] p;  }
+};
+
+template<class T>
+inline bool check_ascending_byte_pattern(const T&t)
+{
+   const unsigned char *pch = &reinterpret_cast<const unsigned char &>(t);
+   const std::size_t max = sizeof(T);
+   for(std::size_t i = 1; i != max; ++i){
+      if( (pch[i-1] != ((unsigned char)(pch[i]-1u))) ){
+         return false;
+      }
+   }
+   return true;
+}
+
+template<class T>
+inline bool check_descending_byte_pattern(const T&t)
+{
+   const unsigned char *pch = &reinterpret_cast<const unsigned char &>(t);
+   const std::size_t max = sizeof(T);
+   for(std::size_t i = 1; i != max; ++i){
+      if( (pch[i-1] != ((unsigned char)(pch[i]+1u))) ){
+         return false;
+      }
+   }
+   return true;
+}
+
+template<class IntDefaultInitAllocVector>
+bool default_init_test()//Test for default initialization
+{
+   const std::size_t Capacity = 100;
+
+   {
+      test::default_init_allocator<int>::reset_pattern(0);
+      test::default_init_allocator<int>::set_ascending(true);
+      IntDefaultInitAllocVector v(Capacity, default_init);
+      typename IntDefaultInitAllocVector::iterator it = v.begin();
+      //Compare with the pattern
+      for(std::size_t i = 0; i != Capacity; ++i, ++it){
+         if(!test::check_ascending_byte_pattern(*it))
+            return false;
+      }
+   }
+   {
+      test::default_init_allocator<int>::reset_pattern(100);
+      test::default_init_allocator<int>::set_ascending(false);
+      IntDefaultInitAllocVector v;
+      v.resize(Capacity, default_init);
+      typename IntDefaultInitAllocVector::iterator it = v.begin();
+      //Compare with the pattern
+      for(std::size_t i = 0; i != Capacity; ++i, ++it){
+         if(!test::check_descending_byte_pattern(*it))
+            return false;
+      }
+   }
+   return true;
+}
+
 template<class V1, class V2>
 bool vector_copyable_only(V1 *, V2 *, boost::container::container_detail::false_type)
 {
@@ -100,7 +218,7 @@ template<class MyBoostVector>
 int vector_test()
 {
    typedef std::vector<int>                     MyStdVector;
-   typedef typename MyBoostVector::value_type     IntType;
+   typedef typename MyBoostVector::value_type   IntType;
    const int max = 100;
 
    if(!test_range_insertion<MyBoostVector>()){