I'd like to replace a bidirectional mapping (2 std::maps so far) with
Boost.Bimap. Being based on Boost.MultiIndex I hope there are some space
savings there (also I could not find specifics in the docs).
I have run into some questions/issues that I hope someone can shed light
upon.
i) I insert a name/value pair like:
typedef boost::bimap MyBimap;
MyBimap myBimap;
bool ok = myBimap.insert( typename MyBimap::value_type(name,val) ).second;
Is it possible (w/o checking afterwards) to find out *why* the insert
failed? (It might be a duplicate on the left or the right side. I want to
print a helpful debug message...)
ii) I would like to use a Bimap in a templated class: Works ok.
When I try to tag the bimap, I get the following errors (using gcc 4.1.2)
error: expected primary-expression before 'template'
error: expected `;' before 'template'
(The errors are the calls to by<country>()
// wrapped tagged_simple_bimap.cpp from the Bimap docs in a template class:
template<typename T>
class X
{
typedef bimap
<
tagged< std::string, country >,
tagged< T , place >
> results_bimap;
...
};
(I have attached the modified example.)
Tagging works if the bimap definition does contain templated types.
Any ideas what I am doing wrong?
iii) I need the order of my insertions at one place in my code.
Do I lose lookup efficiency (on the left side) when I declare my map as:
typedef bimap std::string, int>
(My (bi)map is initialized once and then used for lookups only. Is it better
in that case to store the insertion order in a separate vector?
Or should I go for the more awe-inspiring Boost.Multimap if I want a Bimap
(with efficient lookup) *and* have access to the insertion order?
)
iv) What is the difference between:
typedef bimap< std::string, int, list_of_relation> ...;
and
typedef bimap< vector_ofstd::string, int> ...;
Thank you for a helpful library (collection).
Christoph
