unnecessary_copy_tests.cpp

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// Copyright 2006-2008 Daniel James.
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <boost/unordered_set.hpp>
#include <boost/unordered_map.hpp>
#include "../helpers/test.hpp"

namespace unnecessary_copy_tests
{
    struct count_copies
    {
        static int copies;
        static int moves;
        count_copies() : tag_(0) { ++copies; }
        explicit count_copies(int tag) : tag_(tag) { ++copies; }

        // This bizarre constructor is an attempt to confuse emplace.
        //
        // unordered_map<count_copies, count_copies> x:
        // x.emplace(count_copies(1), count_copies(2));
        // x.emplace(count_copies(1), count_copies(2), count_copies(3));
        //
        // The first emplace should use the single argument constructor twice.
        // The second emplace should use the single argument contructor for
        // the key, and this constructor for the value.
        count_copies(count_copies const&, count_copies const& x)
            : tag_(x.tag_) { ++copies; }

        count_copies(count_copies const& x) : tag_(x.tag_) { ++copies; }
#if defined(BOOST_HAS_RVALUE_REFS)
        count_copies(count_copies&& x) : tag_(x.tag_) {
            x.tag_ = -1; ++moves;
        }
#endif
       int tag_;
    private:
       count_copies& operator=(count_copies const&);
    };

    bool operator==(count_copies const& x, count_copies const& y) {
        return x.tag_ == y.tag_;
    }

    template <class T>
    T source() {
        return T();
    }

    void reset() {
        count_copies::copies = 0;
        count_copies::moves = 0;
    }
}

#if defined(BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP)
namespace boost
#else
namespace unnecessary_copy_tests
#endif
{
    std::size_t hash_value(unnecessary_copy_tests::count_copies const& x) {
        return x.tag_;
    }
}

#define COPY_COUNT(n) \
    if(count_copies::copies != n) { \
        BOOST_ERROR("Wrong number of copies."); \
        std::cerr<<"Number of copies: "<<count_copies::copies<<std::endl; \
    }
#define MOVE_COUNT(n) \
    if(count_copies::moves != n) { \
        BOOST_ERROR("Wrong number of moves."); \
        std::cerr<<"Number of moves: "<<count_copies::moves<<std::endl; \
    }

namespace unnecessary_copy_tests
{
    int count_copies::copies;
    int count_copies::moves;

    template <class T>
    void unnecessary_copy_insert_test(T*)
    {
        T x;
        BOOST_DEDUCED_TYPENAME T::value_type a;
        reset();
        x.insert(a);
        COPY_COUNT(1);
    }

    boost::unordered_set<count_copies>* set;
    boost::unordered_multiset<count_copies>* multiset;
    boost::unordered_map<int, count_copies>* map;
    boost::unordered_multimap<int, count_copies>* multimap;

    UNORDERED_TEST(unnecessary_copy_insert_test,
            ((set)(multiset)(map)(multimap)))

#if defined(BOOST_HAS_RVALUE_REFS) && defined(BOOST_HAS_VARIADIC_TMPL)
    template <class T>
    void unnecessary_copy_emplace_test(T*)
    {
        reset();
        T x;
        BOOST_DEDUCED_TYPENAME T::value_type a;
        COPY_COUNT(1);
        x.emplace(a);
        COPY_COUNT(2);
    }

    template <class T>
    void unnecessary_copy_emplace_rvalue_test(T*)
    {
        reset();
        T x;
        x.emplace(source<BOOST_DEDUCED_TYPENAME T::value_type>());
        COPY_COUNT(1);
    }

    template <class T>
    void unnecessary_copy_emplace_move_test(T*)
    {
        reset();
        T x;
        BOOST_DEDUCED_TYPENAME T::value_type a;
        COPY_COUNT(1); MOVE_COUNT(0);
        x.emplace(std::move(a));
        COPY_COUNT(1); MOVE_COUNT(1);
    }

    UNORDERED_TEST(unnecessary_copy_emplace_test,
            ((set)(multiset)(map)(multimap)))
    UNORDERED_TEST(unnecessary_copy_emplace_rvalue_test,
            ((set)(multiset)(map)(multimap)))
    UNORDERED_TEST(unnecessary_copy_emplace_move_test,
            ((set)(multiset)(map)(multimap)))

    UNORDERED_AUTO_TEST(unnecessary_copy_emplace_set_test)
    {
        reset();
        boost::unordered_set<count_copies> x;
        count_copies a;
        x.insert(a);
        COPY_COUNT(2); MOVE_COUNT(0);

        //
        // 0 arguments
        // 

        // The container will have to create a copy in order to compare with
        // the existing element.
        reset();
        x.emplace();
        COPY_COUNT(1); MOVE_COUNT(0);

        //
        // 1 argument
        // 

        // Emplace should be able to tell that there already is an element
        // without creating a new one.
        reset();
        x.emplace(a);
        COPY_COUNT(0); MOVE_COUNT(0);

        // A new object is created by source, but it shouldn't be moved or
        // copied.
        reset();
        x.emplace(source<count_copies>());
        COPY_COUNT(1); MOVE_COUNT(0);

        // No move should take place.
        reset();
        x.emplace(std::move(a));
        COPY_COUNT(0); MOVE_COUNT(0);

        // Just in case a did get moved...
        count_copies b;

        // The container will have to create a copy in order to compare with
        // the existing element.
        reset();
        x.emplace(b.tag_);
        COPY_COUNT(1); MOVE_COUNT(0);

        //
        // 2 arguments
        //

        // The container will have to create b copy in order to compare with
        // the existing element.

        reset();
        x.emplace(b, b);
        COPY_COUNT(1); MOVE_COUNT(0);
    }

    UNORDERED_AUTO_TEST(unnecessary_copy_emplace_map_test)
    {
        reset();
        boost::unordered_map<count_copies, count_copies> x;
        // TODO: Run tests for pairs without const etc.
        std::pair<count_copies const, count_copies> a;
        x.emplace(a);
        COPY_COUNT(4); MOVE_COUNT(0);

        //
        // 0 arguments
        //

        // COPY_COUNT(1) would be okay here.
        reset();
        x.emplace();
        COPY_COUNT(2); MOVE_COUNT(0);

        //
        // 1 argument
        //

        reset();
        x.emplace(a);
        COPY_COUNT(0); MOVE_COUNT(0);

        // A new object is created by source, but it shouldn't be moved or
        // copied.
        reset();
        x.emplace(source<std::pair<count_copies, count_copies> >());
        COPY_COUNT(2); MOVE_COUNT(0);

        count_copies part;
        reset();
        std::pair<count_copies const&, count_copies const&> a_ref(part, part);
        x.emplace(a_ref);
        COPY_COUNT(0); MOVE_COUNT(0);

        // No move should take place.
        reset();
        x.emplace(std::move(a));
        COPY_COUNT(0); MOVE_COUNT(0);

        // Just in case a did get moved
        std::pair<count_copies const, count_copies> b;

        // This test requires a C++0x std::pair. Which gcc hasn't got yet.
        //reset();
        //x.emplace(b.first.tag_);
        //COPY_COUNT(2); MOVE_COUNT(0);

        //
        // 2 arguments
        //

        reset();
        x.emplace(b.first, b.second);
        COPY_COUNT(0); MOVE_COUNT(0);

        reset();
        x.emplace(source<count_copies>(), source<count_copies>());
        COPY_COUNT(2); MOVE_COUNT(0);

        // source<count_copies> creates a single copy.
        reset();
        x.emplace(b.first, source<count_copies>());
        COPY_COUNT(1); MOVE_COUNT(0);

        reset();
        x.emplace(b.first.tag_, b.second.tag_);
        COPY_COUNT(2); MOVE_COUNT(0);
    }
#endif
}

RUN_TESTS()