examples/registry.cpp

// Copyright 2013-2017 Antony Polukhin

// Distributed under the Boost Software License, Version 1.0.
// (See the accompanying file LICENSE_1_0.txt
// or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)

//[type_index_registry_example
/*`
    The following example shows how an information about a type could be stored.
    Example works with and without RTTI.
*/

#include <boost/type_index.hpp>
#include <boost/unordered_set.hpp>
//<-
// Making `#include <cassert>` visible in docs, while actually using `BOOST_TEST`
// instead of `assert`. This is required to verify correct behavior even if NDEBUG
// is defined and to avoid `unused local variable` warnings with defined NDEBUG.
#include <boost/core/lightweight_test.hpp>
#ifdef assert
#   undef assert
#endif
#define assert(X) BOOST_TEST(X)
    /* !Comment block is not closed intentionaly!
//->
#include <cassert>
//<-
    !Closing comment block! */
//->

int main() {
    boost::unordered_set<boost::typeindex::type_index> types;
    
    // Storing some `boost::type_info`s
    types.insert(boost::typeindex::type_id<int>());
    types.insert(boost::typeindex::type_id<float>());
    
    // `types` variable contains two `boost::type_index`es:
    assert(types.size() == 2);

    // Const, volatile and reference will be striped from the type:
    bool is_inserted = types.insert(boost::typeindex::type_id<const int>()).second;
    assert(!is_inserted);
    assert(types.erase(boost::typeindex::type_id<float&>()) == 1);
    
    // We have erased the `float` type, only `int` remains
    assert(*types.begin() == boost::typeindex::type_id<int>());
}

//] [/type_index_registry_example]