Use Index instead of ptrdiff_t or int, fix random-accessors.

Eigen/src/Core/StlIterators.h

@@ -13,7 +13,7 @@ template<typename XprType,typename Derived>
 class DenseStlIteratorBase
 {
 public:
-  typedef std::ptrdiff_t difference_type;
+  typedef Index difference_type;
   typedef std::random_access_iterator_tag iterator_category;
 
   DenseStlIteratorBase() : mp_xpr(0), m_index(0) {}
@@ -30,13 +30,13 @@ public:
   Derived operator++(int) { Derived prev(derived()); operator++(); return prev;}
   Derived operator--(int) { Derived prev(derived()); operator--(); return prev;}
 
-  friend Derived operator+(const DenseStlIteratorBase& a, int b) { Derived ret(a.derived()); ret += b; return ret; }
+  friend Derived operator+(const DenseStlIteratorBase& a, Index b) { Derived ret(a.derived()); ret += b; return ret; }
-  friend Derived operator-(const DenseStlIteratorBase& a, int b) { Derived ret(a.derived()); ret -= b; return ret; }
+  friend Derived operator-(const DenseStlIteratorBase& a, Index b) { Derived ret(a.derived()); ret -= b; return ret; }
-  friend Derived operator+(int a, const DenseStlIteratorBase& b) { Derived ret(b.derived()); ret += a; return ret; }
+  friend Derived operator+(Index a, const DenseStlIteratorBase& b) { Derived ret(b.derived()); ret += a; return ret; }
-  friend Derived operator-(int a, const DenseStlIteratorBase& b) { Derived ret(b.derived()); ret -= a; return ret; }
+  friend Derived operator-(Index a, const DenseStlIteratorBase& b) { Derived ret(b.derived()); ret -= a; return ret; }
   
-  Derived& operator+=(int b) { m_index += b; return derived(); }
+  Derived& operator+=(Index b) { m_index += b; return derived(); }
-  Derived& operator-=(int b) { m_index -= b; return derived(); }
+  Derived& operator-=(Index b) { m_index -= b; return derived(); }
 
   difference_type operator-(const DenseStlIteratorBase& other) const { eigen_assert(mp_xpr == other.mp_xpr);return m_index - other.m_index; }
 
@@ -85,8 +85,7 @@ public:
   DenseStlIterator(XprType& xpr, Index index) : Base(xpr,index) {}
 
   reference operator*()         const { return   (*mp_xpr)(m_index);   }
-  reference operator[](int i) const { return (*mp_xpr)(i);       }
+  reference operator[](Index i) const { return   (*mp_xpr)(m_index+i); }
-  
   pointer   operator->()        const { return &((*mp_xpr)(m_index)); }
 };
 
@@ -155,8 +154,7 @@ public:
   DenseColStlIterator(XprType& xpr, Index index) : Base(xpr,index) {}
 
   reference operator*()         const { return   (*mp_xpr).col(m_index);   }
-  reference operator[](int i) const { return (*mp_xpr).col(i);       }
+  reference operator[](Index i) const { return   (*mp_xpr).col(m_index+i); }
-  
   pointer   operator->()        const { return &((*mp_xpr).col(m_index)); }
 };
 
@@ -180,8 +178,7 @@ public:
   DenseRowStlIterator(XprType& xpr, Index index) : Base(xpr,index) {}
 
   reference operator*()         const { return   (*mp_xpr).row(m_index);   }
-  reference operator[](int i) const { return (*mp_xpr).row(i);       }
+  reference operator[](Index i) const { return   (*mp_xpr).row(m_index+i); }
-  
   pointer   operator->()        const { return &((*mp_xpr).row(m_index)); }
 };
 

test/stl_iterators.cpp

@@ -59,6 +59,16 @@ void test_range_for_loop(int rows=Rows, int cols=Cols)
   VERIFY_IS_EQUAL(v,w);
 #endif
 
+  if(rows>=3) {
+    VERIFY_IS_EQUAL((v.begin()+rows/2)[1], v(rows/2+1));
+
+    VERIFY_IS_EQUAL((A.allRows().begin()+rows/2)[1], A.row(rows/2+1));
+  }
+
+  if(cols>=3) {
+    VERIFY_IS_EQUAL((A.allCols().begin()+cols/2)[1], A.col(cols/2+1));
+  }
+
   if(rows>=2)
   {
     v(1) = v(0)-Scalar(1);
@@ -84,11 +94,27 @@ void test_range_for_loop(int rows=Rows, int cols=Cols)
     j = internal::random<Index>(0,A.cols()-1);
     typename ColMatrixType::ColXpr Acol = A.col(j);
     std::partial_sum(begin(Acol), end(Acol), begin(v));
-    VERIFY_IS_APPROX(v(seq(1,last)), v(seq(0,last-1))+Acol(seq(1,last)));
+    VERIFY_IS_EQUAL(v(seq(1,last)), v(seq(0,last-1))+Acol(seq(1,last)));
 
     // inplace
     std::partial_sum(begin(Acol), end(Acol), begin(Acol));
-    VERIFY_IS_APPROX(v, Acol);
+    VERIFY_IS_EQUAL(v, Acol);
+  }
+
+  if(rows>=3)
+  {
+    // stress random access
+    v.setRandom();
+    VectorType v1 = v;
+    std::sort(begin(v1),end(v1));
+    std::nth_element(v.begin(), v.begin()+rows/2, v.end());
+    VERIFY_IS_APPROX(v1(rows/2), v(rows/2));
+
+    v.setRandom();
+    v1 = v;
+    std::sort(begin(v1)+rows/2,end(v1));
+    std::nth_element(v.begin()+rows/2, v.begin()+rows/4, v.end());
+    VERIFY_IS_APPROX(v1(rows/4), v(rows/4));
   }
 
 #if EIGEN_HAS_CXX11