From fdced7dbcf24ed99b2ac7a2d1cdc8fa8aa27f64e Mon Sep 17 00:00:00 2001
From: Richard Roberts <richard.jw.roberts@gmail.com>
Date: Thu, 10 Oct 2013 16:39:15 +0000
Subject: [PATCH] Prototype of special comma initializer in unit test only

---
 gtsam/base/tests/testVector.cpp | 131 ++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)

diff --git a/gtsam/base/tests/testVector.cpp b/gtsam/base/tests/testVector.cpp
index a0de5cf54..fd9c1f92c 100644
--- a/gtsam/base/tests/testVector.cpp
+++ b/gtsam/base/tests/testVector.cpp
@@ -23,6 +23,112 @@
 using namespace std;
 using namespace gtsam;
 
+#include <boost/utility/enable_if.hpp>
+
+// Row-vectors not tested
+//template<typename XprType>
+//inline void resizeHelper(XprType& xpr, DenseIndex sizeIncrement,
+//    typename boost::enable_if_c<
+//    XprType::ColsAtCompileTime == Eigen::Dynamic && XprType::RowsAtCompileTime == 1>::type* = 0)
+//{
+//  xpr.conservativeResize(xpr.cols() + sizeIncrement);
+//}
+
+template<typename XprType>
+inline void resizeHelper(XprType& xpr, DenseIndex sizeIncrement,
+    typename boost::enable_if_c<
+    XprType::RowsAtCompileTime == Eigen::Dynamic && XprType::ColsAtCompileTime == 1>::type* = 0)
+{
+  xpr.conservativeResize(xpr.rows() + sizeIncrement);
+}
+
+/// A special comma initializer for Eigen that is implicitly convertible to Vector and Matrix.
+template<typename XprType>
+class SpecialCommaInitializer : public Eigen::CommaInitializer<XprType>
+{
+private:
+  bool dynamic_;
+
+public:
+  typedef Eigen::CommaInitializer<XprType> Base;
+
+  // Forward to base class
+  inline SpecialCommaInitializer(XprType& xpr, const typename XprType::Scalar& s, bool dynamic) :
+      Base(xpr, s), dynamic_(dynamic) {}
+
+  // Forward to base class
+  template<typename OtherDerived>
+  inline SpecialCommaInitializer(XprType& xpr, const Eigen::DenseBase<OtherDerived>& other, bool dynamic) :
+      Base(xpr, other), dynamic_(dynamic) {}
+
+  /// Implicit conversion to expression type, e.g. Vector or Matrix
+  inline operator XprType ()
+  {
+    return this->finished();
+  }
+
+  /// Override base class comma operators to return this class instead of the base class.
+  SpecialCommaInitializer& operator,(const typename XprType::Scalar& s)
+  {
+    // If dynamic, resize the underlying object
+    if(dynamic_)
+    {
+      // Dynamic expansion currently only tested for column-vectors
+      assert(XprType::RowsAtCompileTime == Eigen::Dynamic);
+      // Current col should be zero and row should be at the end
+      assert(Base::m_col == 1);
+      assert(Base::m_row == Base::m_xpr.rows() - Base::m_currentBlockRows);
+      resizeHelper(Base::m_xpr, 1);
+    }
+    (void) Base::operator,(s);
+    return *this;
+  }
+
+  /// Override base class comma operators to return this class instead of the base class.
+  template<typename OtherDerived>
+  SpecialCommaInitializer& operator,(const Eigen::DenseBase<OtherDerived>& other)
+  {
+    // If dynamic, resize the underlying object
+    if(dynamic_)
+    {
+      // Dynamic expansion currently only tested for column-vectors
+      assert(XprType::RowsAtCompileTime == Eigen::Dynamic);
+      // Current col should be zero and row should be at the end
+      assert(Base::m_col == 1);
+      assert(Base::m_row == Base::m_xpr.rows() - Base::m_currentBlockRows);
+      resizeHelper(Base::m_xpr, other.size());
+    }
+    (void) Base::operator,(other);
+    return *this;
+  }
+};
+
+class Vec
+{
+  Vector vector_;
+  bool dynamic_;
+
+public:
+  Vec(DenseIndex size) : vector_(size), dynamic_(false) {}
+
+  Vec() : dynamic_(true) {}
+
+  SpecialCommaInitializer<Vector> operator<< (double s)
+  {
+    if(dynamic_)
+      vector_.resize(1);
+    return SpecialCommaInitializer<Vector>(vector_, s, dynamic_);
+  }
+
+  template<typename OtherDerived>
+  SpecialCommaInitializer<Vector> operator<<(const Eigen::DenseBase<OtherDerived>& other)
+  {
+    if(dynamic_)
+      vector_.resize(other.size());
+    return SpecialCommaInitializer<Vector>(vector_, other, dynamic_);
+  }
+};
+
 /* ************************************************************************* */
 TEST( TestVector, Vector_variants )
 {
@@ -32,6 +138,31 @@ TEST( TestVector, Vector_variants )
   EXPECT(assert_equal(a, b));
 }
 
+/* ************************************************************************* */
+TEST( TestVector, special_comma_initializer)
+{
+  Vector expected(3);
+  expected(0) = 1;
+  expected(1) = 2;
+  expected(2) = 3;
+
+  Vector actual1 = (Vec(3) << 1, 2, 3);
+  Vector actual2((Vec(3) << 1, 2, 3));
+  Vector actual3 = (Vec() << 1, 2, 3);
+
+  Vector subvec1 = (Vec() << 2, 3);
+  Vector actual4 = (Vec() << 1, subvec1);
+
+  Vector subvec2 = (Vec() << 1, 2);
+  Vector actual5 = (Vec() << subvec2, 3);
+
+  EXPECT(assert_equal(expected, actual1));
+  EXPECT(assert_equal(expected, actual2));
+  EXPECT(assert_equal(expected, actual3));
+  EXPECT(assert_equal(expected, actual4));
+  EXPECT(assert_equal(expected, actual5));
+}
+
 /* ************************************************************************* */
 TEST( TestVector, copy )
 {