Add API shortcuts to factors

include/core/factor/factor_base.h

@@ -144,6 +144,14 @@ class FactorBase : public NodeBase, public std::enable_shared_from_this<FactorBa
          **/
         CaptureBasePtr getCapture() const;
 
+        /** \brief Returns a pointer to its frame
+         **/
+        FrameBasePtr getFrame() const;
+
+        /** \brief Returns a pointer to its capture's sensor
+         **/
+        SensorBasePtr getSensor() const;
+
         /** \brief Returns the factor residual size
          **/
         virtual unsigned int getSize() const = 0;

src/factor/factor_base.cpp

@@ -155,6 +155,18 @@ CaptureBasePtr FactorBase::getCapture() const
     return getFeature()->getCapture();
 }
 
+FrameBasePtr FactorBase::getFrame() const
+{
+    assert(getCapture() != nullptr && "calling getFrame before linking with a capture");
+    return getCapture()->getFrame();
+}
+
+SensorBasePtr FactorBase::getSensor() const
+{
+    assert(getCapture() != nullptr && "calling getSensor before linking with a capture");
+    return getCapture()->getSensor();
+}
+
 void FactorBase::setStatus(FactorStatus _status)
 {
     if (getProblem() == nullptr)