Large code refactoring:

- generalize some utilities and move them to Meta (size(), array_size())
 - move handling of all and single indices to IndexedViewHelper.h
 - several cleanup changes

Eigen/src/Core/ArithmeticSequence.h

@@ -12,26 +12,10 @@
 
 namespace Eigen {
 
-//--------------------------------------------------------------------------------
-// Pseudo keywords: all, last, end
-//--------------------------------------------------------------------------------
-
-namespace internal {
-
-struct all_t { all_t() {} };
-
-}
-
-/** \var all
-  * \ingroup Core_Module
-  * Can be used as a parameter to DenseBase::operator()(const RowIndices&, const ColIndices&) to index all rows or columns
-  */
-static const internal::all_t all;
-
 /** \namespace Eigen::placeholders
   * \ingroup Core_Module
   *
-  * Namespace containing symbolic placeholders
+  * Namespace containing symbolic placeholder and identifiers
   */
 namespace placeholders {
 
@@ -268,7 +252,7 @@ typename internal::enable_if<!Symbolic::is_symbolic<FirstType>::value,
                         Symbolic::QuotientExpr<Symbolic::AddExpr<Symbolic::AddExpr<LastTypeDerived,Symbolic::ValueExpr>,
                                                                  Symbolic::ValueExpr>,
                                                Symbolic::ValueExpr>,
-      typename internal::cleanup_seq_type<IncrType>::type> >::type
+                        typename internal::cleanup_seq_type<IncrType>::type> >::type
 seq(FirstType f, const Symbolic::BaseExpr<LastTypeDerived> &l, IncrType incr)
 {
   typedef typename internal::cleanup_seq_type<IncrType>::type CleanedIncrType;
@@ -281,7 +265,7 @@ ArithemeticSequence<FirstTypeDerived,
                                                                                Symbolic::NegateExpr<FirstTypeDerived> >,
                                                              Symbolic::ValueExpr>,
                                           Symbolic::ValueExpr>,
-  typename internal::cleanup_seq_type<IncrType>::type>
+                    typename internal::cleanup_seq_type<IncrType>::type>
 seq(const Symbolic::BaseExpr<FirstTypeDerived> &f, const Symbolic::BaseExpr<LastTypeDerived> &l, IncrType incr)
 {
   typedef typename internal::cleanup_seq_type<IncrType>::type CleanedIncrType;
@@ -293,76 +277,6 @@ seq(const Symbolic::BaseExpr<FirstTypeDerived> &f, const Symbolic::BaseExpr<Last
 
 namespace internal {
 
-template<typename T>
-Index size(const T& x) { return x.size(); }
-
-template<typename T,std::size_t N>
-Index size(const T (&) [N]) { return N; }
-
-template<typename T>
-Index first(const T& x) { return x.first(); }
-
-template<typename T, int XprSize, typename EnableIf = void> struct get_compile_time_size {
-  enum { value = Dynamic };
-};
-
-template<typename T, int XprSize> struct get_compile_time_size<T,XprSize,typename internal::enable_if<((T::SizeAtCompileTime&0)==0)>::type> {
-  enum { value = T::SizeAtCompileTime };
-};
-
-template<typename T, int XprSize, int N> struct get_compile_time_size<const T (&)[N],XprSize> {
-  enum { value = N };
-};
-
-#ifdef EIGEN_HAS_CXX11
-template<typename T, int XprSize, std::size_t N> struct get_compile_time_size<std::array<T,N>,XprSize> {
-  enum { value = N };
-};
-#endif
-
-template<typename T, typename EnableIf = void> struct get_compile_time_incr {
-  enum { value = UndefinedIncr };
-};
-
-template<typename FirstType,typename SizeType,typename IncrType>
-struct get_compile_time_incr<ArithemeticSequence<FirstType,SizeType,IncrType> > {
-  enum { value = get_compile_time<IncrType,DynamicIndex>::value };
-};
-
-
-// MakeIndexing/make_indexing turn an arbitrary object of type T into something usable by MatrixSlice
-template<typename T,typename EnableIf=void>
-struct MakeIndexing {
-  typedef T type;
-};
-
-template<typename T>
-const T& make_indexing(const T& x, Index /*size*/) { return x; }
-
-struct IntAsArray {
-  enum {
-    SizeAtCompileTime = 1
-  };
-  IntAsArray(Index val) : m_value(val) {}
-  Index operator[](Index) const { return m_value; }
-  Index size() const { return 1; }
-  Index first() const { return m_value; }
-  Index m_value;
-};
-
-template<> struct get_compile_time_incr<IntAsArray> {
-  enum { value = 1 }; // 1 or 0 ??
-};
-
-// Turn a single index into something that looks like an array (i.e., that exposes a .size(), and operatro[](int) methods)
-template<typename T>
-struct MakeIndexing<T,typename internal::enable_if<internal::is_integral<T>::value>::type> {
-  // Here we could simply use Array, but maybe it's less work for the compiler to use
-  // a simpler wrapper as IntAsArray
-  //typedef Eigen::Array<Index,1,1> type;
-  typedef IntAsArray type;
-};
-
 // Replace symbolic last/end "keywords" by their true runtime value
 inline Index eval_expr_given_size(Index x, Index /* size */)   { return x; }
 
@@ -381,45 +295,21 @@ struct make_size_type {
   typedef typename internal::conditional<Symbolic::is_symbolic<T>::value, Index, T>::type type;
 };
 
-template<typename FirstType,typename SizeType,typename IncrType>
-struct MakeIndexing<ArithemeticSequence<FirstType,SizeType,IncrType> > {
+template<typename FirstType,typename SizeType,typename IncrType,int XprSize>
+struct IndexedViewCompatibleType<ArithemeticSequence<FirstType,SizeType,IncrType>, XprSize> {
   typedef ArithemeticSequence<Index,typename make_size_type<SizeType>::type,IncrType> type;
 };
 
 template<typename FirstType,typename SizeType,typename IncrType>
 ArithemeticSequence<Index,typename make_size_type<SizeType>::type,IncrType>
-make_indexing(const ArithemeticSequence<FirstType,SizeType,IncrType>& ids, Index size) {
+makeIndexedViewCompatible(const ArithemeticSequence<FirstType,SizeType,IncrType>& ids, Index size) {
   return ArithemeticSequence<Index,typename make_size_type<SizeType>::type,IncrType>(
             eval_expr_given_size(ids.firstObject(),size),eval_expr_given_size(ids.sizeObject(),size),ids.incrObject());
 }
 
-// Convert a symbolic 'all' into a usable range
-// Implementation-wise, it would be more efficient to not having to store m_size since
-// this information is already in the nested expression. To this end, we would need a
-// get_size(indices, underlying_size); function returning indices.size() by default.
-struct AllRange {
-  AllRange(Index size) : m_size(size) {}
-  Index operator[](Index i) const { return i; }
-  Index size() const { return m_size; }
-  Index first() const { return 0; }
-  Index m_size;
-};
-
-template<>
-struct MakeIndexing<all_t> {
-  typedef AllRange type;
-};
-
-inline AllRange make_indexing(all_t , Index size) {
-  return AllRange(size);
-}
-
-template<int XprSize> struct get_compile_time_size<AllRange,XprSize> {
-  enum { value = XprSize };
-};
-
-template<> struct get_compile_time_incr<AllRange> {
-  enum { value = 1 };
+template<typename FirstType,typename SizeType,typename IncrType>
+struct get_compile_time_incr<ArithemeticSequence<FirstType,SizeType,IncrType> > {
+  enum { value = get_compile_time<IncrType,DynamicIndex>::value };
 };
 
 } // end namespace internal
@@ -428,6 +318,7 @@ template<> struct get_compile_time_incr<AllRange> {
 
 namespace legacy {
 // Here are some initial code that I keep here for now to compare the quality of the code generated by the compilers
+// This part will be removed once we have checked everything is right.
 
 struct shifted_last {
   explicit shifted_last(int o) : offset(o) {}
@@ -522,14 +413,14 @@ struct get_compile_time_incr<legacy::ArithemeticSequenceProxyWithBounds<FirstTyp
 };
 
 // Convert a symbolic range into a usable one (i.e., remove last/end "keywords")
-template<typename FirstType,typename LastType,typename IncrType>
-struct MakeIndexing<legacy::ArithemeticSequenceProxyWithBounds<FirstType,LastType,IncrType> > {
+template<typename FirstType,typename LastType,typename IncrType,int XprSize>
+struct IndexedViewCompatibleType<legacy::ArithemeticSequenceProxyWithBounds<FirstType,LastType,IncrType>,XprSize> {
   typedef legacy::ArithemeticSequenceProxyWithBounds<Index,Index,IncrType> type;
 };
 
 template<typename FirstType,typename LastType,typename IncrType>
 legacy::ArithemeticSequenceProxyWithBounds<Index,Index,IncrType>
-make_indexing(const legacy::ArithemeticSequenceProxyWithBounds<FirstType,LastType,IncrType>& ids, Index size) {
+makeIndexedViewCompatible(const legacy::ArithemeticSequenceProxyWithBounds<FirstType,LastType,IncrType>& ids, Index size) {
   return legacy::ArithemeticSequenceProxyWithBounds<Index,Index,IncrType>(
             eval_expr_given_size(ids.firstObject(),size),eval_expr_given_size(ids.lastObject(),size),ids.incrObject());
 }

Eigen/src/Core/IndexedView.h

@@ -19,8 +19,8 @@ struct traits<IndexedView<XprType, RowIndices, ColIndices> >
  : traits<XprType>
 {
   enum {
-    RowsAtCompileTime = get_compile_time_size<RowIndices,traits<XprType>::RowsAtCompileTime>::value,
-    ColsAtCompileTime = get_compile_time_size<ColIndices,traits<XprType>::ColsAtCompileTime>::value,
+    RowsAtCompileTime = array_size<RowIndices>::value,
+    ColsAtCompileTime = array_size<ColIndices>::value,
     MaxRowsAtCompileTime = RowsAtCompileTime != Dynamic ? int(RowsAtCompileTime) : int(traits<XprType>::MaxRowsAtCompileTime),
     MaxColsAtCompileTime = ColsAtCompileTime != Dynamic ? int(ColsAtCompileTime) : int(traits<XprType>::MaxColsAtCompileTime),
 
@@ -38,8 +38,9 @@ struct traits<IndexedView<XprType, RowIndices, ColIndices> >
     XprInnerStride = HasSameStorageOrderAsXprType ? int(inner_stride_at_compile_time<XprType>::ret) : int(outer_stride_at_compile_time<XprType>::ret),
     XprOuterstride = HasSameStorageOrderAsXprType ? int(outer_stride_at_compile_time<XprType>::ret) : int(inner_stride_at_compile_time<XprType>::ret),
 
+    InnerSize = XprTypeIsRowMajor ? ColsAtCompileTime : RowsAtCompileTime,
     IsBlockAlike = InnerIncr==1 && OuterIncr==1,
-    IsInnerPannel = HasSameStorageOrderAsXprType && is_same<AllRange,typename conditional<XprTypeIsRowMajor,ColIndices,RowIndices>::type>::value,
+    IsInnerPannel = HasSameStorageOrderAsXprType && is_same<AllRange<InnerSize>,typename conditional<XprTypeIsRowMajor,ColIndices,RowIndices>::type>::value,
 
     InnerStrideAtCompileTime = InnerIncr<0 || InnerIncr==DynamicIndex || XprInnerStride==Dynamic ? Dynamic : XprInnerStride * InnerIncr,
     OuterStrideAtCompileTime = OuterIncr<0 || OuterIncr==DynamicIndex || XprOuterstride==Dynamic ? Dynamic : XprOuterstride * OuterIncr,

Eigen/src/Core/util/IndexedViewHelper.h

@@ -0,0 +1,111 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2017 Gael Guennebaud <gael.guennebaud@inria.fr>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+#ifndef EIGEN_INDEXED_VIEW_HELPER_H
+#define EIGEN_INDEXED_VIEW_HELPER_H
+
+namespace Eigen {
+
+namespace internal {
+
+// Extract increment/step at compile time
+template<typename T, typename EnableIf = void> struct get_compile_time_incr {
+  enum { value = UndefinedIncr };
+};
+
+// Analogue of std::get<0>(x), but tailored for our needs.
+template<typename T>
+Index first(const T& x) { return x.first(); }
+
+// IndexedViewCompatibleType/makeIndexedViewCompatible turn an arbitrary object of type T into something usable by MatrixSlice
+// The generic implementation is a no-op
+template<typename T,int XprSize,typename EnableIf=void>
+struct IndexedViewCompatibleType {
+  typedef T type;
+};
+
+template<typename T>
+const T& makeIndexedViewCompatible(const T& x, Index /*size*/) { return x; }
+
+//--------------------------------------------------------------------------------
+// Handling of a single Index
+//--------------------------------------------------------------------------------
+
+struct SingleRange {
+  enum {
+    SizeAtCompileTime = 1
+  };
+  SingleRange(Index val) : m_value(val) {}
+  Index operator[](Index) const { return m_value; }
+  Index size() const { return 1; }
+  Index first() const { return m_value; }
+  Index m_value;
+};
+
+template<> struct get_compile_time_incr<SingleRange> {
+  enum { value = 1 }; // 1 or 0 ??
+};
+
+// Turn a single index into something that looks like an array (i.e., that exposes a .size(), and operatro[](int) methods)
+template<typename T, int XprSize>
+struct IndexedViewCompatibleType<T,XprSize,typename internal::enable_if<internal::is_integral<T>::value>::type> {
+  // Here we could simply use Array, but maybe it's less work for the compiler to use
+  // a simpler wrapper as SingleRange
+  //typedef Eigen::Array<Index,1,1> type;
+  typedef SingleRange type;
+};
+
+//--------------------------------------------------------------------------------
+// Handling of all
+//--------------------------------------------------------------------------------
+
+struct all_t { all_t() {} };
+
+// Convert a symbolic 'all' into a usable range type
+template<int XprSize>
+struct AllRange {
+  enum { SizeAtCompileTime = XprSize };
+  AllRange(Index size = XprSize) : m_size(size) {}
+  Index operator[](Index i) const { return i; }
+  Index size() const { return m_size.value(); }
+  Index first() const { return 0; }
+  variable_if_dynamic<Index,XprSize> m_size;
+};
+
+template<int XprSize>
+struct IndexedViewCompatibleType<all_t,XprSize> {
+  typedef AllRange<XprSize> type;
+};
+
+template<typename XprSizeType>
+inline AllRange<get_compile_time<XprSizeType>::value> makeIndexedViewCompatible(all_t , XprSizeType size) {
+  return AllRange<get_compile_time<XprSizeType>::value>(size);
+}
+
+template<int Size> struct get_compile_time_incr<AllRange<Size> > {
+  enum { value = 1 };
+};
+
+} // end namespace internal
+
+
+namespace placeholders {
+
+/** \var all
+  * \ingroup Core_Module
+  * Can be used as a parameter to DenseBase::operator()(const RowIndices&, const ColIndices&) to index all rows or columns
+  */
+static const Eigen::internal::all_t all;
+
+}
+
+} // end namespace Eigen
+
+#endif // EIGEN_INDEXED_VIEW_HELPER_H

Eigen/src/Core/util/Meta.h

@@ -278,6 +278,53 @@ protected:
   EIGEN_DEVICE_FUNC ~noncopyable() {}
 };
 
+/** \internal
+  * Provides access to the number of elements in the object of as a compile-time constant expression.
+  * It "returns" Eigen::Dynamic if the size cannot be resolved at compile-time (default).
+  *
+  * Similar to std::tuple_size, but more general.
+  *
+  * It currently supports:
+  *  - any types T defining T::SizeAtCompileTime
+  *  - plain C arrays as T[N]
+  *  - std::array (c++11)
+  *  - some internal types such as SingleRange and AllRange
+  *
+  * The second template parameter ease SFINAE-based specializations.
+  */
+template<typename T, typename EnableIf = void> struct array_size {
+  enum { value = Dynamic };
+};
+
+template<typename T> struct array_size<T,typename internal::enable_if<((T::SizeAtCompileTime&0)==0)>::type> {
+  enum { value = T::SizeAtCompileTime };
+};
+
+template<typename T, int N> struct array_size<const T (&)[N]> {
+  enum { value = N };
+};
+
+#ifdef EIGEN_HAS_CXX11
+template<typename T, std::size_t N> struct array_size<std::array<T,N> > {
+  enum { value = N };
+};
+#endif
+
+/** \internal
+  * Analogue of the std::size free function.
+  * It returns the size of the container or view \a x of type \c T
+  *
+  * It currently supports:
+  *  - any types T defining a member T::size() const
+  *  - plain C arrays as T[N]
+  *
+  */
+template<typename T>
+Index size(const T& x) { return x.size(); }
+
+template<typename T,std::size_t N>
+Index size(const T (&) [N]) { return N; }
+
 /** \internal
   * Convenient struct to get the result type of a unary or binary functor.
   *