fix(openmmapi): move getNum...() definitions to implementation files (#5009)

Fixes #5001.
Signed-off-by: Yannick Lemke <yannick.lemke@posteo.de>

openmmapi/src/GBSAOBCForce.cpp

@@ -84,3 +84,7 @@ ForceImpl* GBSAOBCForce::createImpl() const {
 void GBSAOBCForce::updateParametersInContext(Context& context) {
     dynamic_cast<GBSAOBCForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
 }
+
+int GBSAOBCForce::getNumParticles() const {
+    return particles.size();
+}

openmmapi/src/GayBerneForce.cpp

@@ -178,3 +178,11 @@ ForceImpl* GayBerneForce::createImpl() const {
 void GayBerneForce::updateParametersInContext(Context& context) {
     dynamic_cast<GayBerneForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
 }
+
+int GayBerneForce::getNumParticles() const {
+    return particles.size();
+}
+
+int GayBerneForce::getNumExceptions() const {
+    return exceptions.size();
+}

openmmapi/src/HarmonicAngleForce.cpp

@@ -95,3 +95,7 @@ void HarmonicAngleForce::setUsesPeriodicBoundaryConditions(bool periodic) {
 bool HarmonicAngleForce::usesPeriodicBoundaryConditions() const {
     return usePeriodic;
 }
+
+int HarmonicAngleForce::getNumAngles() const {
+    return angles.size();
+}

openmmapi/src/HarmonicBondForce.cpp

@@ -93,3 +93,7 @@ void HarmonicBondForce::setUsesPeriodicBoundaryConditions(bool periodic) {
 bool HarmonicBondForce::usesPeriodicBoundaryConditions() const {
     return usePeriodic;
 }
+
+int HarmonicBondForce::getNumBonds() const {
+    return bonds.size();
+}

openmmapi/src/NonbondedForce.cpp

@@ -381,3 +381,23 @@ bool NonbondedForce::getExceptionsUsePeriodicBoundaryConditions() const {
 void NonbondedForce::setExceptionsUsePeriodicBoundaryConditions(bool periodic) {
     exceptionsUsePeriodic = periodic;
 }
+
+int NonbondedForce::getNumParticles() const {
+    return particles.size();
+}
+
+int NonbondedForce::getNumExceptions() const {
+    return exceptions.size();
+}
+
+int NonbondedForce::getNumGlobalParameters() const {
+    return globalParameters.size();
+}
+
+int NonbondedForce::getNumParticleParameterOffsets() const {
+    return particleOffsets.size();
+}
+
+int NonbondedForce::getNumExceptionParameterOffsets() const {
+    return exceptionOffsets.size();
+}

openmmapi/src/PeriodicTorsionForce.cpp

@@ -99,3 +99,7 @@ void PeriodicTorsionForce::setUsesPeriodicBoundaryConditions(bool periodic) {
 bool PeriodicTorsionForce::usesPeriodicBoundaryConditions() const {
     return usePeriodic;
 }
+
+int PeriodicTorsionForce::getNumTorsions() const {
+    return periodicTorsions.size();
+}

openmmapi/src/RBTorsionForce.cpp

@@ -88,3 +88,7 @@ void RBTorsionForce::setUsesPeriodicBoundaryConditions(bool periodic) {
 bool RBTorsionForce::usesPeriodicBoundaryConditions() const {
     return usePeriodic;
 }
+
+int RBTorsionForce::getNumTorsions() const {
+    return rbTorsions.size();
+}

openmmapi/src/System.cpp

@@ -154,3 +154,15 @@ bool System::usesPeriodicBoundaryConditions() const {
 
     return uses_pbc;
 }
+
+int System::getNumParticles() const {
+    return masses.size();
+}
+
+int System::getNumConstraints() const {
+    return constraints.size();
+}
+
+int System::getNumForces() const {
+    return forces.size();
+}