Add check for null context inside integrator.step()

openmmapi/src/CustomIntegrator.cpp

@@ -94,6 +94,8 @@ double CustomIntegrator::computeKineticEnergy() {
 }
 
 void CustomIntegrator::step(int steps) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");  
     globalsAreCurrent = false;
     for (int i = 0; i < steps; ++i) {
         kernel.getAs<IntegrateCustomStepKernel>().execute(*context, *this, forcesAreValid);

openmmapi/src/LangevinIntegrator.cpp

@@ -72,6 +72,8 @@ double LangevinIntegrator::computeKineticEnergy() {
 }
 
 void LangevinIntegrator::step(int steps) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");  
     for (int i = 0; i < steps; ++i) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);

openmmapi/src/VariableLangevinIntegrator.cpp

@@ -75,6 +75,8 @@ double VariableLangevinIntegrator::computeKineticEnergy() {
 }
 
 void VariableLangevinIntegrator::step(int steps) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");  
     for (int i = 0; i < steps; ++i) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);
@@ -83,6 +85,8 @@ void VariableLangevinIntegrator::step(int steps) {
 }
 
 void VariableLangevinIntegrator::stepTo(double time) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");
     while (time > context->getTime()) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);

openmmapi/src/VariableVerletIntegrator.cpp

@@ -70,6 +70,8 @@ double VariableVerletIntegrator::computeKineticEnergy() {
 }
 
 void VariableVerletIntegrator::step(int steps) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");
     for (int i = 0; i < steps; ++i) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);
@@ -78,6 +80,8 @@ void VariableVerletIntegrator::step(int steps) {
 }
 
 void VariableVerletIntegrator::stepTo(double time) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");  
     while (time > context->getTime()) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);

openmmapi/src/VerletIntegrator.cpp

@@ -69,6 +69,8 @@ double VerletIntegrator::computeKineticEnergy() {
 }
 
 void VerletIntegrator::step(int steps) {
+    if (context == NULL)
+        throw OpenMMException("This Integrator is not bound to a context!");
     for (int i = 0; i < steps; ++i) {
         context->updateContextState();
         context->calcForcesAndEnergy(true, false);