feat: make the propagator maintain the frame and size of the input St…

…ate (#246)

* feat: make the propagator maintain the frame and size of the input State in the output

* chore: uncomment other tests

* Apply suggestions from code review

Co-authored-by: Vishwa Shah <vishwa2710@gmail.com>

* refactor: make propagator StateBuilder a local variable and fix syntax errors from uncommenting code

* fix: remove hard-coded gcrf usage in Propagated model

---------

Co-authored-by: Vishwa Shah <vishwa2710@gmail.com>

include/OpenSpaceToolkit/Astrodynamics/Trajectory/Propagator.hpp

@@ -32,6 +32,7 @@
 #include <OpenSpaceToolkit/Astrodynamics/Trajectory/Orbit/Model.hpp>
 #include <OpenSpaceToolkit/Astrodynamics/Trajectory/State.hpp>
 #include <OpenSpaceToolkit/Astrodynamics/Trajectory/State/NumericalSolver.hpp>
+#include <OpenSpaceToolkit/Astrodynamics/Trajectory/StateBuilder.hpp>
 
 namespace ostk
 {
@@ -55,6 +56,7 @@ using ostk::physics::time::Instant;
 using ostk::astro::trajectory::state::NumericalSolver;
 using ostk::astro::EventCondition;
 using ostk::astro::trajectory::State;
+using ostk::astro::trajectory::StateBuilder;
 using ostk::astro::Dynamics;
 using ostk::astro::flight::system::SatelliteSystem;
 

src/OpenSpaceToolkit/Astrodynamics/Trajectory/Orbit/Models/Propagated.cpp

@@ -27,7 +27,6 @@ using ostk::physics::units::Time;
 
 static const Derived::Unit GravitationalParameterSIUnit =
     Derived::Unit::GravitationalParameter(Length::Unit::Meter, Time::Unit::Second);
-static const Shared<const Frame> gcrfSPtr = Frame::GCRF();
 
 Propagated::Propagated(const Propagator& aPropagator, const State& aState)
     : Model(),
@@ -140,6 +139,9 @@ Array<State> Propagated::calculateStatesAt(const Array<Instant>& anInstantArray)
         }
     }
 
+    // Builder for output states based on cached array
+    StateBuilder outputStateBuilder = {this->cachedStateArray_.accessFirst()};
+
     Array<State> allStates = Array<State>::Empty();
 
     // Maintain counter separately so as to only iterate once through instant array
@@ -213,12 +215,12 @@ Array<State> Propagated::calculateStatesAt(const Array<Instant>& anInstantArray)
                 (forwardStates[k].accessCoordinates() * forwardWeight +
                  backwardStates[k].accessCoordinates() * backwardWeight);
 
-            averagedStates.add({
-                instants[k],
-                coordinates,
-                gcrfSPtr,
-                propagator_.accessCoordinatesBroker(),
-            });
+            averagedStates.add(
+                outputStateBuilder.build(
+                    instants[k],
+                    coordinates
+                )
+            );
         }
 
         allStates.add(averagedStates);

src/OpenSpaceToolkit/Astrodynamics/Trajectory/Propagator.cpp

@@ -143,18 +143,21 @@ State Propagator::calculateStateAt(const State& aState, const Instant& anInstant
         throw ostk::core::error::runtime::Undefined("Propagator");
     }
 
-    const State state = {
-        aState.accessInstant(),
-        aState.inFrame(Propagator::IntegrationFrameSPtr).extractCoordinates(this->coordinatesBrokerSPtr_->getSubsets()),
-        Propagator::IntegrationFrameSPtr,
-        this->coordinatesBrokerSPtr_,
-    };
+    const StateBuilder solverStateBuilder = {Propagator::IntegrationFrameSPtr, coordinatesBrokerSPtr_};
+
+    const State solverInputState = solverStateBuilder.reduce(aState.inFrame(Propagator::IntegrationFrameSPtr));
 
-    return numericalSolver_.integrateTime(
-        state,
+    const State solverOutputState = numericalSolver_.integrateTime(
+        solverInputState,
         anInstant,
-        Dynamics::GetSystemOfEquations(this->dynamicsContexts_, state.accessInstant(), Propagator::IntegrationFrameSPtr)
+        Dynamics::GetSystemOfEquations(
+            this->dynamicsContexts_, solverInputState.accessInstant(), Propagator::IntegrationFrameSPtr
+        )
     );
+
+    const StateBuilder outputStateBuilder = {aState};
+
+    return outputStateBuilder.expand(solverOutputState.inFrame(aState.accessFrame()), aState);
 }
 
 NumericalSolver::ConditionSolution Propagator::calculateStateToCondition(
@@ -168,20 +171,21 @@ NumericalSolver::ConditionSolution Propagator::calculateStateToCondition(
 
     const Instant startInstant = aState.getInstant();
 
-    const State state = {
-        aState.accessInstant(),
-        aState.inFrame(Propagator::IntegrationFrameSPtr).extractCoordinates(this->coordinatesBrokerSPtr_->getSubsets()),
-        Propagator::IntegrationFrameSPtr,
-        this->coordinatesBrokerSPtr_,
-    };
+    const StateBuilder solverStateBuilder = {Propagator::IntegrationFrameSPtr, coordinatesBrokerSPtr_};
+
+    const State solverInputState = solverStateBuilder.reduce(aState.inFrame(Propagator::IntegrationFrameSPtr));
 
-    const NumericalSolver::ConditionSolution conditionSolution = numericalSolver_.integrateTime(
-        state,
+    NumericalSolver::ConditionSolution conditionSolution = numericalSolver_.integrateTime(
+        solverInputState,
         anInstant,
         Dynamics::GetSystemOfEquations(this->dynamicsContexts_, startInstant, Propagator::IntegrationFrameSPtr),
         anEventCondition
     );
 
+    const StateBuilder outputStateBuilder = {aState};
+
+    conditionSolution.state = outputStateBuilder.expand(conditionSolution.state.inFrame(aState.accessFrame()), aState);
+
     return conditionSolution;
 }
 
@@ -210,20 +214,19 @@ Array<State> Propagator::calculateStatesAt(const State& aState, const Array<Inst
         }
     }
 
-    const State state = {
-        aState.accessInstant(),
-        aState.inFrame(Propagator::IntegrationFrameSPtr).extractCoordinates(this->coordinatesBrokerSPtr_->getSubsets()),
-        Propagator::IntegrationFrameSPtr,
-        this->coordinatesBrokerSPtr_,
-    };
+    const StateBuilder solverStateBuilder = {Propagator::IntegrationFrameSPtr, coordinatesBrokerSPtr_};
+
+    const State solverInputState = solverStateBuilder.reduce(aState.inFrame(Propagator::IntegrationFrameSPtr));
 
-    const Instant startInstant = state.accessInstant();
+    const Instant startInstant = solverInputState.accessInstant();
 
     Array<Instant> forwardInstants;
     forwardInstants.reserve(anInstantArray.getSize());
     Array<Instant> backwardInstants;
     backwardInstants.reserve(anInstantArray.getSize());
 
+    const StateBuilder outputStateBuilder(aState);
+
     for (const Instant& anInstant : anInstantArray)
     {
         if (anInstant <= startInstant)
@@ -241,7 +244,7 @@ Array<State> Propagator::calculateStatesAt(const State& aState, const Array<Inst
     if (!forwardInstants.isEmpty())
     {
         forwardPropagatedStates = numericalSolver_.integrateTime(
-            state,
+            solverInputState,
             forwardInstants,
             Dynamics::GetSystemOfEquations(this->dynamicsContexts_, startInstant, Propagator::IntegrationFrameSPtr)
         );
@@ -254,15 +257,23 @@ Array<State> Propagator::calculateStatesAt(const State& aState, const Array<Inst
         std::reverse(backwardInstants.begin(), backwardInstants.end());
 
         backwardPropagatedStates = numericalSolver_.integrateTime(
-            state,
+            solverInputState,
             backwardInstants,
             Dynamics::GetSystemOfEquations(this->dynamicsContexts_, startInstant, Propagator::IntegrationFrameSPtr)
         );
 
         std::reverse(backwardPropagatedStates.begin(), backwardPropagatedStates.end());
     }
 
-    return backwardPropagatedStates + forwardPropagatedStates;
+    Array<State> outputStates;
+    outputStates.reserve(backwardPropagatedStates.getSize() + forwardPropagatedStates.getSize());
+
+    for (const State& solverOutputState : backwardPropagatedStates + forwardPropagatedStates)
+    {
+        outputStates.add(outputStateBuilder.expand(solverOutputState.inFrame(aState.accessFrame()), aState));
+    }
+
+    return outputStates;
 }
 
 void Propagator::print(std::ostream& anOutputStream, bool displayDecorator) const