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#ifndef VECTOR_UTILITY_H
#define VECTOR_UTILITY_H
// stl vector doesnt deallocate memory on itself.
// push_back and resizing increases memory by a factor of 2, when growing
// pop_back, resizing and even clear do not deallocate any memory
// This of course wastes a lot of memory, fortunately there is the swap trick to
// bring back memory usage to normality
//#include <algorithm>
template<class T>
inline void trim_vector (T& v)
{
if (v.capacity () != v.size ())
{
T temp = v;
temp.swap (v);
}
}
// The following functions do the same as their vector member function
// equivalents, only they allocate exactly the requested amount of memory.
template<class T>
inline void resize_trimmed (T& v, unsigned int sz)
{
// the vector is growing
if (sz > v.size ())
{
if (sz != v.capacity ())
{
T temp (v.get_allocator());
temp.reserve (sz);
temp.assign (v.begin (), v.end ());
temp.resize (sz);
temp.swap (v);
}
else
v.resize (sz);
}
// the vector is shrinking
else if (sz < v.size ())
{
T temp (v.begin (), v.begin () + sz, v.get_allocator());
temp.swap (v);
}
}
template<class T>
inline void reserve_trimmed (T& v, unsigned int sz)
{
if (sz != v.capacity ())
{
T temp;
temp.reserve (sz);
temp.assign (v.begin (), v.end ());
temp.swap (v);
}
}
template<class T>
inline void clear_trimmed (T& v)
{
T temp;
temp.swap (v);
}
template<class T>
inline void push_back_trimmed (T& vec, const typename T::value_type& value)
{
if (vec.size () + 1 != vec.capacity ())
{
T temp;
temp.reserve (vec.size () + 1);
temp.assign (vec.begin (), vec.end ());
temp.push_back (value);
temp.swap (vec);
}
else
vec.push_back (value);
}
template<class T>
inline void erase_trimmed (T& vec, typename T::iterator i)
{
AssertIf (i == vec.end ());
T temp;
temp.reserve (vec.size () - 1);
temp.assign (vec.begin (), i);
temp.insert (temp.end (), ++i, vec.end ());
vec.swap (temp);
}
#endif
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