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Implementing std::hash specialization for MCCompLabel #1645

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Merged
sawenzel merged 1 commit into from
Jan 30, 2019
Merged

Implementing std::hash specialization for MCCompLabel #1645

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20 changes: 18 additions & 2 deletions DataFormats/simulation/include/SimulationDataFormat/MCCompLabel.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,6 @@ class MCCompLabel

ULong64_t mLabel = NotSet; ///< MC label encoding MCtrack ID and MCevent origin

void checkFieldConsistensy();

public:
// number of bits reserved for MC track ID, DON'T modify this, since the
// track ID might be negative
Expand All @@ -35,6 +33,11 @@ class MCCompLabel
static constexpr int nbitsSrcID = 8; // number of bits reserved for MC source ID
// the rest of the bits is reserved at the moment

// check if the fields are defined consistently
static_assert(nbitsTrackID == sizeof(int) * 8, "TrackID must have int size");
static_assert(nbitsTrackID + nbitsEvID + nbitsSrcID <= sizeof(ULong64_t) * 8,
"Fields cannot be stored in 64 bits");

// mask to extract MC track ID
static constexpr ULong64_t maskTrackID = (ul0x1 << nbitsTrackID) - 1;
// mask to extract MC track ID
Expand Down Expand Up @@ -102,4 +105,17 @@ class MCCompLabel

std::ostream& operator<<(std::ostream& os, const o2::MCCompLabel& c);

namespace std
{
// defining std::hash for MCCompLabel in order to be used with unordered_maps
template <>
struct hash<o2::MCCompLabel> {
public:
size_t operator()(o2::MCCompLabel const& label) const
{
return static_cast<uint64_t>(label);
}
};
} // namespace std

#endif
9 changes: 0 additions & 9 deletions DataFormats/simulation/src/MCCompLabel.cxx
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Expand Up @@ -37,12 +37,3 @@ std::ostream& operator<<(std::ostream& os, const o2::MCCompLabel& c)
}
return os;
}

//_____________________________________________
void MCCompLabel::checkFieldConsistensy()
{
// check if the fields are defined consistently
static_assert(nbitsTrackID==sizeof(int)*8, "TrackID must have int size");
static_assert(nbitsTrackID+nbitsEvID+nbitsSrcID<=sizeof(ULong64_t)*8,
"Fields cannot be stored in 64 bits");
}
6 changes: 6 additions & 0 deletions DataFormats/simulation/test/testMCCompLabel.cxx
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Expand Up @@ -25,16 +25,22 @@ BOOST_AUTO_TEST_CASE(MCCompLabel_test)
BOOST_CHECK(!lbUndef.isSet()); // test invalid label status

int ev = 200, src = 10;
std::unordered_map<MCCompLabel, int> labelMap;
for (int tr=-100;tr<200;tr+=150) {
MCCompLabel lb(tr, ev, src);
std::cout << "Input: [" << src << '/' << ev << '/'
<< std::setw(6) << tr << ']' << std::endl;
std::cout << "Encoded: " << lb << " (packed: " << ULong_t(lb) << ")" << std::endl;
labelMap[lb] = tr;
int trE, evE, srcE;
lb.get(trE, evE, srcE);
std::cout << "Decoded: [" << srcE << '/' << evE << '/'
<< std::setw(6) << trE << ']' << std::endl;

BOOST_CHECK(tr == trE && ev == evE && src == srcE);
}

for (auto& [key, value] : labelMap) {
BOOST_CHECK(key.getTrackID() == value);
}
}