feat: Add measurement emplace functions (#3627)

Recently, the measurement EDM was replaced by a memory-optimal bulk storage, but this makes it a bit harder to add new measurements to a collection. This commit adds two new emplace functions which variadically allow users to add measurements, similar to how they might use `std::vector::emplace_back`.

Examples/Algorithms/Digitization/src/MeasurementCreation.cpp

@@ -31,12 +31,6 @@ ActsExamples::VariableBoundMeasurementProxy ActsExamples::createMeasurement(
   return Acts::visit_measurement(
       dParams.indices.size(), [&](auto dim) -> VariableBoundMeasurementProxy {
         auto [indices, par, cov] = measurementConstituents<dim>(dParams);
-        FixedBoundMeasurementProxy<dim> measurement =
-            container.makeMeasurement<dim>();
-        measurement.setSourceLink(sl);
-        measurement.setSubspaceIndices(indices);
-        measurement.parameters() = par;
-        measurement.covariance() = cov;
-        return measurement;
+        return container.emplaceMeasurement<dim>(sl, indices, par, cov);
       });
 }

Examples/Framework/include/ActsExamples/EventData/Measurement.hpp

@@ -17,8 +17,10 @@
 #include "Acts/EventData/detail/CalculateResiduals.hpp"
 #include "Acts/EventData/detail/ParameterTraits.hpp"
 #include "Acts/EventData/detail/PrintParameters.hpp"
+#include "ActsExamples/EventData/MeasurementConcept.hpp"
 
 #include <array>
+#include <concepts>
 #include <cstddef>
 #include <iosfwd>
 #include <type_traits>
@@ -117,6 +119,12 @@ class MeasurementContainer {
     return getMeasurement<Size>(addMeasurement(Size));
   }
 
+  template <typename... Args>
+  VariableProxy emplaceMeasurement(std::uint8_t size, Args&&... args);
+
+  template <std::size_t Size, typename... Args>
+  FixedProxy<Size> emplaceMeasurement(Args&&... args);
+
   template <bool Const>
   class IteratorImpl {
    public:
@@ -263,7 +271,7 @@ class MeasurementProxyBase {
   void setSubspaceIndices(const IndexContainer& indices)
     requires(!ReadOnly)
   {
-    assert(checkSubspaceIndices(indices, FullSize, size()) &&
+    assert(Acts::checkSubspaceIndices(indices, FullSize, size()) &&
            "Invalid indices");
     std::transform(indices.begin(), indices.end(),
                    self().subspaceIndexVector().begin(),
@@ -282,19 +290,45 @@ class MeasurementProxyBase {
     return self().subspaceHelper().expandMatrix(self().covariance());
   }
 
+  /// @brief Construct the measurement from a sourcelink, subspace vector,
+  /// parameters, and covariance.
+  ///
+  template <typename Subspace, typename ParameterDerived,
+            typename CovarianceDerived>
+  void fill(const Acts::SourceLink& source_link, Subspace&& subspace,
+            const Eigen::DenseBase<ParameterDerived>& parameters,
+            const Eigen::DenseBase<CovarianceDerived>& covariance)
+    requires(!ReadOnly)
+  {
+    setSourceLink(source_link);
+    self().setSubspaceIndices(std::forward<Subspace>(subspace));
+    self().parameters() = parameters;
+    self().covariance() = covariance;
+  }
+
+  /// @brief Construct the measurement from a sourcelink, subspace vector,
+  /// parameters, and covariance.
+  ///
+  template <MeasurementConcept OtherDerived>
+  void fill(const OtherDerived& other)
+    requires(!ReadOnly)
+  {
+    assert(size() == other.size() && "Size mismatch");
+    fill(other.sourceLink(), other.subspaceIndexVector(), other.parameters(),
+         other.covariance());
+  }
+
   /// @brief Copy the data from another measurement
   /// @tparam OtherDerived The derived measurement proxy class of the other
   ///         measurement
   /// @param other The other measurement proxy
   template <typename OtherDerived>
   void copyFrom(const OtherDerived& other)
-    requires(!ReadOnly)
+    requires(!ReadOnly) && requires {
+      { this->fill(other) };
+    }
   {
-    assert(size() == other.size() && "Size mismatch");
-    setSourceLink(other.sourceLink());
-    self().subspaceIndexVector() = other.subspaceIndexVector();
-    self().parameters() = other.parameters();
-    self().covariance() = other.covariance();
+    fill(other);
   }
 
  protected:
@@ -485,4 +519,24 @@ class VariableMeasurementProxy
   }
 };
 
+template <typename... Args>
+MeasurementContainer::VariableProxy MeasurementContainer::emplaceMeasurement(
+    std::uint8_t size, Args&&... args) {
+  VariableProxy meas = makeMeasurement(size);
+
+  meas.fill(std::forward<Args>(args)...);
+
+  return meas;
+}
+
+template <std::size_t Size, typename... Args>
+MeasurementContainer::FixedProxy<Size> MeasurementContainer::emplaceMeasurement(
+    Args&&... args) {
+  FixedProxy<Size> meas = makeMeasurement<Size>();
+
+  meas.fill(std::forward<Args>(args)...);
+
+  return meas;
+}
+
 }  // namespace ActsExamples

Examples/Framework/include/ActsExamples/EventData/MeasurementConcept.hpp

@@ -0,0 +1,25 @@
+// This file is part of the Acts project.
+//
+// Copyright (C) 2023 CERN for the benefit of the Acts project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#pragma once
+
+#include "Acts/EventData/SourceLink.hpp"
+
+#include <concepts>
+
+namespace ActsExamples {
+
+template <typename T>
+concept MeasurementConcept = requires(const T& m) {
+  { m.size() } -> std::integral;
+  { m.sourceLink() } -> Acts::Concepts::decayed_same_as<Acts::SourceLink>;
+  { m.subspaceIndexVector() };
+  { m.parameters() };
+  { m.covariance() };
+};
+}  // namespace ActsExamples

Examples/Io/Csv/src/CsvMeasurementReader.cpp

@@ -273,8 +273,7 @@ ActsExamples::ProcessCode ActsExamples::CsvMeasurementReader::read(
 
   MeasurementContainer measurements;
   for (auto& [_, meas] : orderedMeasurements) {
-    auto measurement = measurements.makeMeasurement(meas.size());
-    measurement.copyFrom(meas);
+    measurements.emplaceMeasurement(meas.size(), meas);
   }
 
   // Generate measurement-particles-map

Tests/UnitTests/Examples/EventData/MeasurementTests.cpp

@@ -70,6 +70,24 @@ BOOST_DATA_TEST_CASE(VariableBoundOne, bd::make(boundIndices), index) {
                     sourceOrig);
 }
 
+BOOST_DATA_TEST_CASE(VariableBoundOneEmplace, bd::make(boundIndices), index) {
+  MeasurementContainer container;
+
+  auto [params, cov] = generateParametersCovariance<ActsScalar, 1u>(rng);
+
+  FixedBoundMeasurementProxy<1> meas =
+      container.emplaceMeasurement<1>(source, std::array{index}, params, cov);
+
+  BOOST_CHECK_EQUAL(meas.size(), 1);
+  for (auto i : boundIndices) {
+    BOOST_CHECK_EQUAL(meas.contains(i), i == index);
+  }
+  BOOST_CHECK_EQUAL(meas.parameters(), params);
+  BOOST_CHECK_EQUAL(meas.covariance(), cov);
+  BOOST_CHECK_EQUAL(meas.sourceLink().template get<TestSourceLink>(),
+                    sourceOrig);
+}
+
 BOOST_AUTO_TEST_CASE(VariableBoundAll) {
   MeasurementContainer container;
 
@@ -92,6 +110,27 @@ BOOST_AUTO_TEST_CASE(VariableBoundAll) {
   BOOST_CHECK_EQUAL(meas.sourceLink().get<TestSourceLink>(), sourceOrig);
 }
 
+BOOST_AUTO_TEST_CASE(VariableBoundAllEmplace) {
+  MeasurementContainer container;
+
+  auto [params, cov] = generateBoundParametersCovariance(rng);
+
+  FixedBoundMeasurementProxy<eBoundSize> meas =
+      container.emplaceMeasurement<eBoundSize>(
+          source,
+          std::array{eBoundLoc0, eBoundLoc1, eBoundTime, eBoundPhi, eBoundTheta,
+                     eBoundQOverP},
+          params, cov);
+
+  BOOST_CHECK_EQUAL(meas.size(), eBoundSize);
+  for (auto i : boundIndices) {
+    BOOST_CHECK(meas.contains(i));
+  }
+  BOOST_CHECK_EQUAL(meas.parameters(), params);
+  BOOST_CHECK_EQUAL(meas.covariance(), cov);
+  BOOST_CHECK_EQUAL(meas.sourceLink().get<TestSourceLink>(), sourceOrig);
+}
+
 BOOST_AUTO_TEST_CASE(VariableBoundReassign) {
   MeasurementContainer container;