From 58026905ae4a608abac33f59a782beae590a8371 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Wed, 25 May 2016 11:04:14 -0700
Subject: Added support for statically known lists of pairs of indices

---
 .../Eigen/CXX11/src/Tensor/TensorIndexList.h       | 215 ++++++++++++++++++---
 1 file changed, 188 insertions(+), 27 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h b/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
index 4f0f4fd75..7aebd6f28 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
@@ -10,6 +10,22 @@
 #ifndef EIGEN_CXX11_TENSOR_TENSOR_INDEX_LIST_H
 #define EIGEN_CXX11_TENSOR_TENSOR_INDEX_LIST_H
 
+/*namespace Eigen {
+
+template <typename Index> struct IndexPair {
+  constexpr EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE IndexPair() : first(0), second(0) {}
+  constexpr EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE IndexPair(Index f, Index s) : first(f), second(s) {}
+
+  EIGEN_DEVICE_FUNC void set(IndexPair<Index> val) {
+    first = val.first;
+    second = val.second;
+  }
+
+  Index first;
+  Index second;
+};
+}*/
+
 #if EIGEN_HAS_CONSTEXPR && EIGEN_HAS_VARIADIC_TEMPLATES
 
 #define EIGEN_HAS_INDEX_LIST
@@ -45,6 +61,24 @@ struct type2index {
   }
 };
 
+// This can be used with IndexPairList to get compile-time constant pairs,
+// such as IndexPairList<type2indexpair<1,2>, type2indexpair<3,4>>().
+template <DenseIndex f, DenseIndex s>
+struct type2indexpair {
+  static const DenseIndex first = f;
+  static const DenseIndex second = s;
+
+  constexpr EIGEN_DEVICE_FUNC operator IndexPair<DenseIndex>() const {
+    return IndexPair<DenseIndex>(f, s);
+  }
+
+  EIGEN_DEVICE_FUNC void set(const IndexPair<DenseIndex>& val) {
+    eigen_assert(val.first == f);
+    eigen_assert(val.second == s);
+  }
+};
+
+
 template<DenseIndex n> struct NumTraits<type2index<n> >
 {
   typedef DenseIndex Real;
@@ -72,6 +106,16 @@ EIGEN_DEVICE_FUNC void update_value(type2index<n>& val, DenseIndex new_val) {
   val.set(new_val);
 }
 
+template <typename T>
+EIGEN_DEVICE_FUNC void update_value(T& val, IndexPair<DenseIndex> new_val) {
+  val = new_val;
+}
+template <DenseIndex f, DenseIndex s>
+EIGEN_DEVICE_FUNC void update_value(type2indexpair<f, s>& val, IndexPair<DenseIndex> new_val) {
+  val.set(new_val);
+}
+
+
 template <typename T>
 struct is_compile_time_constant {
   static constexpr bool value = false;
@@ -94,7 +138,22 @@ struct is_compile_time_constant<const type2index<idx>& > {
   static constexpr bool value = true;
 };
 
-
+template <DenseIndex f, DenseIndex s>
+struct is_compile_time_constant<type2indexpair<f, s> > {
+  static constexpr bool value = true;
+};
+template <DenseIndex f, DenseIndex s>
+struct is_compile_time_constant<const type2indexpair<f, s> > {
+  static constexpr bool value = true;
+};
+template <DenseIndex f, DenseIndex s>
+struct is_compile_time_constant<type2indexpair<f, s>& > {
+  static constexpr bool value = true;
+};
+template <DenseIndex f, DenseIndex s>
+struct is_compile_time_constant<const type2indexpair<f, s>& > {
+  static constexpr bool value = true;
+};
 
 
 template<typename... T>
@@ -184,31 +243,32 @@ template <typename T, typename... O>
 
 
 
-template <DenseIndex Idx>
+template <DenseIndex Idx, typename ValueT>
 struct tuple_coeff {
   template <typename... T>
-  EIGEN_DEVICE_FUNC static constexpr DenseIndex get(const DenseIndex i, const IndexTuple<T...>& t) {
-    return array_get<Idx>(t) * (i == Idx) + tuple_coeff<Idx-1>::get(i, t) * (i != Idx);
+  EIGEN_DEVICE_FUNC static constexpr ValueT get(const DenseIndex i, const IndexTuple<T...>& t) {
+    //    return array_get<Idx>(t) * (i == Idx) + tuple_coeff<Idx-1>::get(i, t) * (i != Idx);
+    return (i == Idx ? array_get<Idx>(t) : tuple_coeff<Idx-1, ValueT>::get(i, t));
   }
   template <typename... T>
-  EIGEN_DEVICE_FUNC static void set(const DenseIndex i, IndexTuple<T...>& t, const DenseIndex value) {
+  EIGEN_DEVICE_FUNC static void set(const DenseIndex i, IndexTuple<T...>& t, const ValueT& value) {
     if (i == Idx) {
       update_value(array_get<Idx>(t), value);
     } else {
-      tuple_coeff<Idx-1>::set(i, t, value);
+      tuple_coeff<Idx-1, ValueT>::set(i, t, value);
     }
   }
 
   template <typename... T>
   EIGEN_DEVICE_FUNC static constexpr bool value_known_statically(const DenseIndex i, const IndexTuple<T...>& t) {
     return ((i == Idx) & is_compile_time_constant<typename IndexTupleExtractor<Idx, T...>::ValType>::value) ||
-        tuple_coeff<Idx-1>::value_known_statically(i, t);
+        tuple_coeff<Idx-1, ValueT>::value_known_statically(i, t);
   }
 
   template <typename... T>
   EIGEN_DEVICE_FUNC static constexpr bool values_up_to_known_statically(const IndexTuple<T...>& t) {
     return is_compile_time_constant<typename IndexTupleExtractor<Idx, T...>::ValType>::value &&
-        tuple_coeff<Idx-1>::values_up_to_known_statically(t);
+        tuple_coeff<Idx-1, ValueT>::values_up_to_known_statically(t);
   }
 
   template <typename... T>
@@ -216,19 +276,19 @@ struct tuple_coeff {
     return is_compile_time_constant<typename IndexTupleExtractor<Idx, T...>::ValType>::value &&
            is_compile_time_constant<typename IndexTupleExtractor<Idx, T...>::ValType>::value &&
            array_get<Idx>(t) > array_get<Idx-1>(t) &&
-           tuple_coeff<Idx-1>::values_up_to_statically_known_to_increase(t);
+           tuple_coeff<Idx-1, ValueT>::values_up_to_statically_known_to_increase(t);
   }
 };
 
-template <>
-struct tuple_coeff<0> {
+template <typename ValueT>
+struct tuple_coeff<0, ValueT> {
   template <typename... T>
-  EIGEN_DEVICE_FUNC static constexpr DenseIndex get(const DenseIndex i, const IndexTuple<T...>& t) {
+  EIGEN_DEVICE_FUNC static constexpr ValueT get(const DenseIndex /*i*/, const IndexTuple<T...>& t) {
     //  eigen_assert (i == 0);  // gcc fails to compile assertions in constexpr
-    return array_get<0>(t) * (i == 0);
+    return array_get<0>(t)/* * (i == 0)*/;
   }
   template <typename... T>
-  EIGEN_DEVICE_FUNC static void set(const DenseIndex i, IndexTuple<T...>& t, const DenseIndex value) {
+  EIGEN_DEVICE_FUNC static void set(const DenseIndex i, IndexTuple<T...>& t, const ValueT value) {
     eigen_assert (i == 0);
     update_value(array_get<0>(t), value);
   }
@@ -254,13 +314,13 @@ struct tuple_coeff<0> {
 template<typename FirstType, typename... OtherTypes>
 struct IndexList : internal::IndexTuple<FirstType, OtherTypes...> {
   EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC constexpr DenseIndex operator[] (const DenseIndex i) const {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::get(i, *this);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::get(i, *this);
   }
   EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC constexpr DenseIndex get(const DenseIndex i) const {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::get(i, *this);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::get(i, *this);
   }
   EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC void set(const DenseIndex i, const DenseIndex value) {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::set(i, *this, value);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::set(i, *this, value);
   }
 
   EIGEN_DEVICE_FUNC constexpr IndexList(const internal::IndexTuple<FirstType, OtherTypes...>& other) : internal::IndexTuple<FirstType, OtherTypes...>(other) { }
@@ -268,14 +328,14 @@ struct IndexList : internal::IndexTuple<FirstType, OtherTypes...> {
   EIGEN_DEVICE_FUNC constexpr IndexList() : internal::IndexTuple<FirstType, OtherTypes...>() { }
 
   EIGEN_DEVICE_FUNC constexpr bool value_known_statically(const DenseIndex i) const {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::value_known_statically(i, *this);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::value_known_statically(i, *this);
   }
   EIGEN_DEVICE_FUNC constexpr bool all_values_known_statically() const {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::values_up_to_known_statically(*this);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::values_up_to_known_statically(*this);
   }
 
   EIGEN_DEVICE_FUNC constexpr bool values_statically_known_to_increase() const {
-    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1>::values_up_to_statically_known_to_increase(*this);
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::values_up_to_statically_known_to_increase(*this);
   }
 };
 
@@ -286,6 +346,23 @@ constexpr IndexList<FirstType, OtherTypes...> make_index_list(FirstType val1, Ot
 }
 
 
+template<typename FirstType, typename... OtherTypes>
+struct IndexPairList : internal::IndexTuple<FirstType, OtherTypes...> {
+  EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC constexpr IndexPair<DenseIndex> operator[] (const DenseIndex i) const {
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, IndexPair<DenseIndex>>::get(i, *this);
+  }
+  EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC void set(const DenseIndex i, const IndexPair<DenseIndex> value) {
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...>>::value-1, IndexPair<DenseIndex> >::set(i, *this, value);
+  }
+
+  EIGEN_DEVICE_FUNC  constexpr IndexPairList(const internal::IndexTuple<FirstType, OtherTypes...>& other) : internal::IndexTuple<FirstType, OtherTypes...>(other) { }
+  EIGEN_DEVICE_FUNC  constexpr IndexPairList() : internal::IndexTuple<FirstType, OtherTypes...>() { }
+
+  EIGEN_DEVICE_FUNC constexpr bool value_known_statically(const DenseIndex i) const {
+    return internal::tuple_coeff<internal::array_size<internal::IndexTuple<FirstType, OtherTypes...> >::value-1, DenseIndex>::value_known_statically(i, *this);
+  }
+};
+
 namespace internal {
 
 template<typename FirstType, typename... OtherTypes> size_t array_prod(const IndexList<FirstType, OtherTypes...>& sizes) {
@@ -303,6 +380,13 @@ template<typename FirstType, typename... OtherTypes> struct array_size<const Ind
   static const size_t value = array_size<IndexTuple<FirstType, OtherTypes...> >::value;
 };
 
+template<typename FirstType, typename... OtherTypes> struct array_size<IndexPairList<FirstType, OtherTypes...> > {
+  static const size_t value = std::tuple_size<std::tuple<FirstType, OtherTypes...> >::value;
+};
+template<typename FirstType, typename... OtherTypes> struct array_size<const IndexPairList<FirstType, OtherTypes...> > {
+  static const size_t value = std::tuple_size<std::tuple<FirstType, OtherTypes...> >::value;
+};
+
 template<DenseIndex N, typename FirstType, typename... OtherTypes> EIGEN_DEVICE_FUNC constexpr DenseIndex array_get(IndexList<FirstType, OtherTypes...>& a) {
   return IndexTupleExtractor<N, FirstType, OtherTypes...>::get_val(a);
 }
@@ -472,6 +556,57 @@ struct index_statically_lt_impl<const IndexList<FirstType, OtherTypes...> > {
   }
 };
 
+
+
+template <typename Tx>
+struct index_pair_first_statically_eq_impl {
+  EIGEN_DEVICE_FUNC static constexpr bool run(DenseIndex, DenseIndex) {
+    return false;
+  }
+};
+
+template <typename FirstType, typename... OtherTypes>
+struct index_pair_first_statically_eq_impl<IndexPairList<FirstType, OtherTypes...> > {
+  EIGEN_DEVICE_FUNC static constexpr bool run(const DenseIndex i, const DenseIndex value) {
+    return IndexPairList<FirstType, OtherTypes...>().value_known_statically(i) &
+        (IndexPairList<FirstType, OtherTypes...>()[i].first == value);
+  }
+};
+
+template <typename FirstType, typename... OtherTypes>
+struct index_pair_first_statically_eq_impl<const IndexPairList<FirstType, OtherTypes...> > {
+  EIGEN_DEVICE_FUNC static constexpr bool run(const DenseIndex i, const DenseIndex value) {
+    return IndexPairList<FirstType, OtherTypes...>().value_known_statically(i) &
+        (IndexPairList<FirstType, OtherTypes...>()[i].first == value);
+  }
+};
+
+
+
+template <typename Tx>
+struct index_pair_second_statically_eq_impl {
+  EIGEN_DEVICE_FUNC static constexpr bool run(DenseIndex, DenseIndex) {
+    return false;
+  }
+};
+
+template <typename FirstType, typename... OtherTypes>
+struct index_pair_second_statically_eq_impl<IndexPairList<FirstType, OtherTypes...> > {
+  EIGEN_DEVICE_FUNC static constexpr bool run(const DenseIndex i, const DenseIndex value) {
+    return IndexPairList<FirstType, OtherTypes...>().value_known_statically(i) &
+        (IndexPairList<FirstType, OtherTypes...>()[i].second == value);
+  }
+};
+
+template <typename FirstType, typename... OtherTypes>
+struct index_pair_second_statically_eq_impl<const IndexPairList<FirstType, OtherTypes...> > {
+  EIGEN_DEVICE_FUNC static constexpr bool run(const DenseIndex i, const DenseIndex value) {
+    return IndexPairList<FirstType, OtherTypes...>().value_known_statically(i) &
+        (IndexPairList<FirstType, OtherTypes...>()[i].second == value);
+  }
+};
+
+
 }  // end namespace internal
 }  // end namespace Eigen
 
@@ -482,53 +617,69 @@ namespace internal {
 
 template <typename T>
 struct index_known_statically_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run(const DenseIndex) {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(const DenseIndex) {
     return false;
   }
 };
 
 template <typename T>
 struct all_indices_known_statically_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run() {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run() {
     return false;
   }
 };
 
 template <typename T>
 struct indices_statically_known_to_increase_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run() {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run() {
     return false;
   }
 };
 
 template <typename T>
 struct index_statically_eq_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run(DenseIndex, DenseIndex) {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
     return false;
   }
 };
 
 template <typename T>
 struct index_statically_ne_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run(DenseIndex, DenseIndex) {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
     return false;
   }
 };
 
 template <typename T>
 struct index_statically_gt_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run(DenseIndex, DenseIndex) {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
     return false;
   }
 };
 
 template <typename T>
 struct index_statically_lt_impl {
-  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE static bool run(DenseIndex, DenseIndex) {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
+    return false;
+  }
+};
+
+template <typename Tx>
+struct index_pair_first_statically_eq_impl {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
+    return false;
+  }
+};
+
+template <typename Tx>
+struct index_pair_second_statically_eq_impl {
+  static EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool run(DenseIndex, DenseIndex) {
     return false;
   }
 };
 
+
+
 }  // end namespace internal
 }  // end namespace Eigen
 
@@ -572,6 +723,16 @@ static EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR bool index_statically_lt(DenseIndex i,
   return index_statically_lt_impl<T>::run(i, value);
 }
 
+template <typename T>
+static EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR bool index_pair_first_statically_eq(DenseIndex i, DenseIndex value) {
+  return index_pair_first_statically_eq_impl<T>::run(i, value);
+}
+
+template <typename T>
+static EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR bool index_pair_second_statically_eq(DenseIndex i, DenseIndex value) {
+  return index_pair_second_statically_eq_impl<T>::run(i, value);
+}
+
 }  // end namespace internal
 }  // end namespace Eigen
 
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