implement dummy >> operator

gtsam/hybrid/HybridGaussianProductFactor.cpp

@@ -103,4 +103,10 @@ HybridGaussianProductFactor HybridGaussianProductFactor::removeEmpty() const {
   return {Base(*this, emptyGaussian)};
 }
 
+/* *******************************************************************************/
+std::istream& operator>>(std::istream& is, GaussianFactorGraphValuePair& pair) {
+  // Dummy, don't do anything
+  return is;
+}
+
 }  // namespace gtsam

gtsam/hybrid/HybridGaussianProductFactor.h

@@ -22,6 +22,8 @@
 #include <gtsam/inference/Key.h>
 #include <gtsam/linear/GaussianFactorGraph.h>
 
+#include <iostream>
+
 namespace gtsam {
 
 class HybridGaussianFactor;
@@ -55,14 +57,6 @@ class GTSAM_EXPORT HybridGaussianProductFactor
    */
   HybridGaussianProductFactor(Base&& tree) : Base(std::move(tree)) {}
 
-  /// Deleted constructor since we don't have istream operator for
-  /// GaussianFactorGraphValuePair
-  HybridGaussianProductFactor(const std::vector<DiscreteKey>& labelCs,
-                              const std::string& table) {
-    throw std::runtime_error(
-        "HybridGaussianProductFactor: No way to construct.");
-  }
-
   ///@}
 
   /// @name Operators
@@ -140,4 +134,14 @@ template <>
 struct traits<HybridGaussianProductFactor>
     : public Testable<HybridGaussianProductFactor> {};
 
+/**
+ * Create a dummy overload of >> for GaussianFactorGraphValuePair
+ * so that HybridGaussianProductFactor compiles
+ * with the constructor
+ * `DecisionTree(const std::vector<LabelC>& labelCs, const std::string& table)`.
+ *
+ * Needed to compile on Windows.
+ */
+std::istream& operator>>(std::istream& is, GaussianFactorGraphValuePair& pair);
+
 }  // namespace gtsam