From 744dd0afbbe064dc7dc3d92c77b9306560cbe742 Mon Sep 17 00:00:00 2001
From: Joshua <joshua.crawford@levno.com>
Date: Wed, 30 May 2018 07:52:54 +1200
Subject: [PATCH 01/15] Remove uses of std::iterator (deprecated in C++17)

Detailed reasoning for the deprecation is provided by the paper proposing deprecation (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0174r2.html) and a related LWG issue (https://cplusplus.github.io/LWG/issue2438).

This was the only issue preventing a clean compile with VS 15.7.2 with c++17/c++latest set as the target language

The issue could be resolved in two ways. Providing a custom replacement to std::iterator (a very simple structure) or by providing the 5 required typedefs. The only functional difference from my reading is that the typedefs are not immediately available to the implementer with the inheritance. I find the inline typedefs to be clearer hence the selection in this commit
---
 include/xlnt/workbook/worksheet_iterator.hpp | 33 +++++++++++-------
 include/xlnt/worksheet/cell_iterator.hpp     | 36 ++++++++++++--------
 include/xlnt/worksheet/range_iterator.hpp    | 34 ++++++++++--------
 3 files changed, 61 insertions(+), 42 deletions(-)

diff --git a/include/xlnt/workbook/worksheet_iterator.hpp b/include/xlnt/workbook/worksheet_iterator.hpp
index d0ac56e7..b2830f88 100644
--- a/include/xlnt/workbook/worksheet_iterator.hpp
+++ b/include/xlnt/workbook/worksheet_iterator.hpp
@@ -37,18 +37,22 @@ class worksheet;
 // because one needs to point at a const workbook and the other needs
 // to point at a non-const workbook stored as a member variable, respectively.
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using ws_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    worksheet, std::ptrdiff_t, worksheet *, worksheet>;
 
 /// <summary>
 /// An iterator which is used to iterate over the worksheets in a workbook.
 /// </summary>
-class XLNT_API worksheet_iterator : public ws_iter_type
+class XLNT_API worksheet_iterator
 {
 public:
+    /// <summary>
+    /// iterator tags required for use with standard algorithms and adapters
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = worksheet;
+    using difference_type = std::ptrdiff_t;
+    using pointer = worksheet *;
+    using reference = worksheet; // intentionally value
+
     /// <summary>
     /// Constructs a worksheet iterator from a workbook and sheet index.
     /// </summary>
@@ -106,18 +110,21 @@ private:
 };
 
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using c_ws_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    const worksheet, std::ptrdiff_t, const worksheet *, const worksheet>;
-
 /// <summary>
 /// An iterator which is used to iterate over the worksheets in a const workbook.
 /// </summary>
-class XLNT_API const_worksheet_iterator : public c_ws_iter_type
+class XLNT_API const_worksheet_iterator
 {
 public:
+    /// <summary>
+    /// iterator tags required for use with standard algorithms and adapters
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = const worksheet;
+    using difference_type = std::ptrdiff_t;
+    using pointer = const worksheet *;
+    using reference = const worksheet; // intentionally value
+
     /// <summary>
     /// Constructs a worksheet iterator from a workbook and sheet index.
     /// </summary>
diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index 496dd6a9..5f7b24eb 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -40,18 +40,21 @@ class cell;
 class cell_reference;
 class range_reference;
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using c_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    cell, std::ptrdiff_t, cell *, cell>;
-
 /// <summary>
 /// A cell iterator iterates over a 1D range by row or by column.
 /// </summary>
-class XLNT_API cell_iterator : public c_iter_type
+class XLNT_API cell_iterator
 {
 public:
+    /// <summary>
+    /// iterator tags required for use with standard algorithms and adapters
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = cell;
+    using difference_type = std::ptrdiff_t;
+    using pointer = cell *;
+    using reference = cell; // intentionally value
+
     /// <summary>
     /// Constructs a cell_iterator from a worksheet, range, and iteration settings.
     /// </summary>
@@ -135,7 +138,7 @@ private:
     /// If true, cells that don't exist in the worksheet will be skipped during iteration.
     /// </summary>
     bool skip_null_;
-    
+
     /// <summary>
     /// If true, when on the last column, the cursor will continue to the next row
     /// (and vice versa when iterating in column-major order) until reaching the
@@ -144,18 +147,21 @@ private:
     bool wrap_;
 };
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using cc_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    const cell, std::ptrdiff_t, const cell *, const cell>;
-
 /// <summary>
 /// A cell iterator iterates over a 1D range by row or by column.
 /// </summary>
-class XLNT_API const_cell_iterator : public cc_iter_type
+class XLNT_API const_cell_iterator
 {
 public:
+    /// <summary>
+    /// iterator tags required for use with standard algorithms and adapters
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = const cell;
+    using difference_type = std::ptrdiff_t;
+    using pointer = const cell *;
+    using reference = const cell; // intentionally value
+
     /// <summary>
     /// Constructs a cell_iterator from a worksheet, range, and iteration settings.
     /// </summary>
diff --git a/include/xlnt/worksheet/range_iterator.hpp b/include/xlnt/worksheet/range_iterator.hpp
index cdd51d84..351e257f 100644
--- a/include/xlnt/worksheet/range_iterator.hpp
+++ b/include/xlnt/worksheet/range_iterator.hpp
@@ -35,19 +35,22 @@ namespace xlnt {
 
 class cell_vector;
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using r_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    cell_vector, std::ptrdiff_t, cell_vector *, cell_vector>;
-
 /// <summary>
 /// An iterator used by worksheet and range for traversing
 /// a 2D grid of cells by row/column then across that row/column.
 /// </summary>
-class XLNT_API range_iterator : public r_iter_type
+class XLNT_API range_iterator
 {
 public:
+    /// <summary>
+    /// iterator tags required for use with standard algorithms and adapters
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = cell_vector;
+    using difference_type = std::ptrdiff_t;
+    using pointer = cell_vector *;
+    using reference = cell_vector; // intentionally value
+
     /// <summary>
     /// Constructs a range iterator on a worksheet, cell pointing to the current
     /// row or column, range bounds, an order, and whether or not to skip null column/rows.
@@ -127,19 +130,22 @@ private:
     bool skip_null_;
 };
 
-/// <summary>
-/// Alias the parent class of this iterator to increase clarity.
-/// </summary>
-using cr_iter_type = std::iterator<std::bidirectional_iterator_tag,
-    const cell_vector, std::ptrdiff_t, const cell_vector *, const cell_vector>;
-
 /// <summary>
 /// A const version of range_iterator which does not allow modification
 /// to the dereferenced cell_vector.
 /// </summary>
-class XLNT_API const_range_iterator : public cr_iter_type
+class XLNT_API const_range_iterator
 {
 public:
+    /// <summary>
+    /// this iterator meets the interface requirements of bidirection_iterator
+    /// </summary>
+    using iterator_category = std::bidirectional_iterator_tag;
+    using value_type = const cell_vector;
+    using difference_type = std::ptrdiff_t;
+    using pointer = const cell_vector *;
+    using reference = const cell_vector; // intentionally value
+
     /// <summary>
     /// Constructs a range iterator on a worksheet, cell pointing to the current
     /// row or column, range bounds, an order, and whether or not to skip null column/rows.

From 92ac3a2a2ea25731561cb91650a10f16147ef389 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 13:07:02 +1200
Subject: [PATCH 02/15] cell_iterator - rule of 5/0

For rule of 5/0, where no implementation is required, all 5 operations have been declared as defaulted. This is less likely to forget definitions for all 5 if required
- removed forwarding of copy to assignment (which was defaulted already) in favour of defaulted copy ctor
- added defaulted move assignment/ctor and destructor
---
 include/xlnt/worksheet/cell_iterator.hpp | 37 +++++++++++++++++++++---
 source/worksheet/cell_iterator.cpp       | 10 -------
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index 5f7b24eb..64e5c9b2 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -64,12 +64,27 @@ public:
     /// <summary>
     /// Constructs a cell_iterator as a copy of an existing cell_iterator.
     /// </summary>
-    cell_iterator(const cell_iterator &other);
+    cell_iterator(const cell_iterator &) = default;
 
     /// <summary>
     /// Assigns this iterator to match the data in rhs.
     /// </summary>
-    cell_iterator &operator=(const cell_iterator &rhs) = default;
+    cell_iterator &operator=(const cell_iterator &) = default;
+
+    /// <summary>
+    /// Constructs a cell_iterator by moving from a cell_iterator temporary
+    /// </summary>
+    cell_iterator(const cell_iterator &&) = default;
+
+    /// <summary>
+    /// Assigns this iterator to from a cell_iterator temporary
+    /// </summary>
+    cell_iterator &operator=(const cell_iterator &&) = default;
+
+    /// <summary>
+    /// destructor for const_cell_iterator
+    /// </summary>
+    ~cell_iterator() = default;
 
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
@@ -169,15 +184,29 @@ public:
         const range_reference &limits, major_order order, bool skip_null, bool wrap);
 
     /// <summary>
-    /// Constructs a cell_iterator as a copy of an existing cell_iterator.
+    /// Constructs a const_cell_iterator as a copy of an existing cell_iterator.
     /// </summary>
-    const_cell_iterator(const const_cell_iterator &other);
+    const_cell_iterator(const const_cell_iterator &) = default;
 
     /// <summary>
     /// Assigns this iterator to match the data in rhs.
     /// </summary>
     const_cell_iterator &operator=(const const_cell_iterator &) = default;
 
+    /// <summary>
+    /// Constructs a const_cell_iterator by moving from a const_cell_iterator temporary
+    /// </summary>
+    const_cell_iterator(const const_cell_iterator &&) = default;
+
+    /// <summary>
+    /// Assigns this iterator to from a const_cell_iterator temporary
+    /// </summary>
+    const_cell_iterator &operator=(const const_cell_iterator &&) = default;
+
+    /// <summary>
+    /// destructor for const_cell_iterator
+    /// </summary>
+    ~const_cell_iterator() = default;
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
diff --git a/source/worksheet/cell_iterator.cpp b/source/worksheet/cell_iterator.cpp
index bad750ba..25aa7196 100644
--- a/source/worksheet/cell_iterator.cpp
+++ b/source/worksheet/cell_iterator.cpp
@@ -58,16 +58,6 @@ const_cell_iterator::const_cell_iterator(worksheet ws, const cell_reference &cur
     }
 }
 
-cell_iterator::cell_iterator(const cell_iterator &other)
-{
-    *this = other;
-}
-
-const_cell_iterator::const_cell_iterator(const const_cell_iterator &other)
-{
-    *this = other;
-}
-
 bool cell_iterator::operator==(const cell_iterator &other) const
 {
     return ws_ == other.ws_

From 20e72d69e5aaf795a182b6e5fd94782b42734a88 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 13:16:54 +1200
Subject: [PATCH 03/15] cell_iterator - operator* const overloads

Users may still want to derederence a const iterator (note: not a const_iterator).
Also use the "reference" typedef to ensure there is only 1 source of information
---
 include/xlnt/worksheet/cell_iterator.hpp | 14 +++++++++++++-
 source/worksheet/cell_iterator.cpp       |  8 ++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index 64e5c9b2..b11818f6 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -89,7 +89,13 @@ public:
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
-    cell operator*();
+    reference operator*();
+
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    const reference operator*() const;
+
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
@@ -207,6 +213,12 @@ public:
     /// destructor for const_cell_iterator
     /// </summary>
     ~const_cell_iterator() = default;
+
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    const reference operator*() const;
+
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
diff --git a/source/worksheet/cell_iterator.cpp b/source/worksheet/cell_iterator.cpp
index 25aa7196..e4c334e9 100644
--- a/source/worksheet/cell_iterator.cpp
+++ b/source/worksheet/cell_iterator.cpp
@@ -265,14 +265,18 @@ const_cell_iterator const_cell_iterator::operator++(int)
     return old;
 }
 
-cell cell_iterator::operator*()
+cell_iterator::reference cell_iterator::operator*()
 {
     return ws_.cell(cursor_);
 }
 
-const cell const_cell_iterator::operator*() const
+const cell_iterator::reference cell_iterator::operator*() const
 {
     return ws_.cell(cursor_);
 }
 
+const const_cell_iterator::reference const_cell_iterator::operator*() const
+{
+    return ws_.cell(cursor_);
+}
 } // namespace xlnt

From 1c4f9c7ed2905722cf22dc1e85420fe5ec2143c9 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 13:18:39 +1200
Subject: [PATCH 04/15] cell iterator - add operator->

Implementation just forwards to operator*, but this is a typical operator in the iterator API and is suprising and inconvenient that it is not present
---
 include/xlnt/worksheet/cell_iterator.hpp | 11 ++++++++++-
 source/worksheet/cell_iterator.cpp       | 16 ++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index b11818f6..9e179057 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -96,6 +96,15 @@ public:
     /// </summary>
     const reference operator*() const;
 
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    reference operator->();
+
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    const reference operator->() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
@@ -222,7 +231,7 @@ public:
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
-    const cell operator*() const;
+    const reference operator->() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
diff --git a/source/worksheet/cell_iterator.cpp b/source/worksheet/cell_iterator.cpp
index e4c334e9..d1f66252 100644
--- a/source/worksheet/cell_iterator.cpp
+++ b/source/worksheet/cell_iterator.cpp
@@ -279,4 +279,20 @@ const const_cell_iterator::reference const_cell_iterator::operator*() const
 {
     return ws_.cell(cursor_);
 }
+
+cell_iterator::reference cell_iterator::operator->()
+{
+    return operator*();
+}
+
+const cell_iterator::reference cell_iterator::operator->() const
+{
+    return operator*();
+}
+
+const const_cell_iterator::reference const_cell_iterator::operator->() const
+{
+    return operator*();
+}
+
 } // namespace xlnt

From dc020622c055d5b1b2a2c5539d538ba8696ae385 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:21:21 +1200
Subject: [PATCH 05/15] cell iterator - move parameters aren't const

copy/paste error
---
 include/xlnt/worksheet/cell_iterator.hpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index 9e179057..8dc53737 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -74,12 +74,12 @@ public:
     /// <summary>
     /// Constructs a cell_iterator by moving from a cell_iterator temporary
     /// </summary>
-    cell_iterator(const cell_iterator &&) = default;
+    cell_iterator(cell_iterator &&) = default;
 
     /// <summary>
     /// Assigns this iterator to from a cell_iterator temporary
     /// </summary>
-    cell_iterator &operator=(const cell_iterator &&) = default;
+    cell_iterator &operator=(cell_iterator &&) = default;
 
     /// <summary>
     /// destructor for const_cell_iterator
@@ -211,12 +211,12 @@ public:
     /// <summary>
     /// Constructs a const_cell_iterator by moving from a const_cell_iterator temporary
     /// </summary>
-    const_cell_iterator(const const_cell_iterator &&) = default;
+    const_cell_iterator(const_cell_iterator &&) = default;
 
     /// <summary>
     /// Assigns this iterator to from a const_cell_iterator temporary
     /// </summary>
-    const_cell_iterator &operator=(const const_cell_iterator &&) = default;
+    const_cell_iterator &operator=(const_cell_iterator &&) = default;
 
     /// <summary>
     /// destructor for const_cell_iterator

From 1e66824af06319a86f71555fd9476d15ed41479b Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:27:20 +1200
Subject: [PATCH 06/15] range_iterator - rule of 5/0

For rule of 5/0, where no implementation is required, all 5 operations have been declared as defaulted. This is less likely to forget definitions for all 5 if required
- removed forwarding of copy ctor to assignment (which was defaulted already) in favour of defaulted copy ctor
- added defaulted move assignment/ctor and destructor
---
 include/xlnt/worksheet/range_iterator.hpp | 58 +++++++++++++++++------
 source/worksheet/range_iterator.cpp       | 10 ----
 2 files changed, 44 insertions(+), 24 deletions(-)

diff --git a/include/xlnt/worksheet/range_iterator.hpp b/include/xlnt/worksheet/range_iterator.hpp
index 351e257f..5e942f73 100644
--- a/include/xlnt/worksheet/range_iterator.hpp
+++ b/include/xlnt/worksheet/range_iterator.hpp
@@ -59,20 +59,35 @@ public:
         const range_reference &bounds, major_order order, bool skip_null);
 
     /// <summary>
-    /// Copy constructor.
+    /// Default copy constructor.
     /// </summary>
-    range_iterator(const range_iterator &other);
-
-    /// <summary>
-    /// Dereference the iterator to return a column or row.
-    /// </summary>
-    cell_vector operator*() const;
+    range_iterator(const range_iterator &) = default;
 
     /// <summary>
     /// Default assignment operator.
     /// </summary>
     range_iterator &operator=(const range_iterator &) = default;
 
+    /// <summary>
+    /// Default move constructor.
+    /// </summary>
+    range_iterator(range_iterator &&) = default;
+
+    /// <summary>
+    /// Default move assignment operator.
+    /// </summary>
+    range_iterator &operator=(range_iterator &&) = default;
+
+    /// <summary>
+    /// Default destructor
+    /// </summary>
+    ~range_iterator() = default;
+
+    /// <summary>
+    /// Dereference the iterator to return a column or row.
+    /// </summary>
+    cell_vector operator*() const;
+
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
     /// </summary>
@@ -154,20 +169,35 @@ public:
         const range_reference &bounds, major_order order, bool skip_null);
 
     /// <summary>
-    /// Copy constructor.
+    /// Default copy constructor.
     /// </summary>
-    const_range_iterator(const const_range_iterator &other);
-
-    /// <summary>
-    /// Dereferennce the iterator to return the current column/row.
-    /// </summary>
-    const cell_vector operator*() const;
+    const_range_iterator(const const_range_iterator &) = default;
 
     /// <summary>
     /// Default assignment operator.
     /// </summary>
     const_range_iterator &operator=(const const_range_iterator &) = default;
 
+    /// <summary>
+    /// Default move constructor.
+    /// </summary>
+    const_range_iterator(const_range_iterator &&) = default;
+
+    /// <summary>
+    /// Default move assignment operator.
+    /// </summary>
+    const_range_iterator &operator=(const_range_iterator &&) = default;
+
+    /// <summary>
+    /// Default destructor
+    /// </summary>
+    ~const_range_iterator() = default;
+
+    /// <summary>
+    /// Dereferennce the iterator to return the current column/row.
+    /// </summary>
+    const cell_vector operator*() const;
+
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
     /// </summary>
diff --git a/source/worksheet/range_iterator.cpp b/source/worksheet/range_iterator.cpp
index 2da73d5c..57208d26 100644
--- a/source/worksheet/range_iterator.cpp
+++ b/source/worksheet/range_iterator.cpp
@@ -47,11 +47,6 @@ range_iterator::range_iterator(worksheet &ws, const cell_reference &cursor,
     }
 }
 
-range_iterator::range_iterator(const range_iterator &other)
-{
-    *this = other;
-}
-
 bool range_iterator::operator==(const range_iterator &other) const
 {
     return ws_ == other.ws_
@@ -168,11 +163,6 @@ const_range_iterator::const_range_iterator(const worksheet &ws, const cell_refer
     }
 }
 
-const_range_iterator::const_range_iterator(const const_range_iterator &other)
-{
-    *this = other;
-}
-
 bool const_range_iterator::operator==(const const_range_iterator &other) const
 {
     return ws_ == other.ws_

From bc8cd21d676d1f08dfeec228407c6fca595e0088 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:37:10 +1200
Subject: [PATCH 07/15] range_iterator - operator* const overloads

Users may still want to dereference a const iterator (note: not a const_iterator).
Also use the "reference" typedef to ensure there is only 1 source of information
---
 include/xlnt/worksheet/range_iterator.hpp | 9 +++++++--
 source/worksheet/range_iterator.cpp       | 9 +++++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/xlnt/worksheet/range_iterator.hpp b/include/xlnt/worksheet/range_iterator.hpp
index 5e942f73..c6f43979 100644
--- a/include/xlnt/worksheet/range_iterator.hpp
+++ b/include/xlnt/worksheet/range_iterator.hpp
@@ -86,7 +86,12 @@ public:
     /// <summary>
     /// Dereference the iterator to return a column or row.
     /// </summary>
-    cell_vector operator*() const;
+    reference operator*();
+
+    /// <summary>
+    /// Dereference the iterator to return a column or row.
+    /// </summary>
+    const reference operator*() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
@@ -196,7 +201,7 @@ public:
     /// <summary>
     /// Dereferennce the iterator to return the current column/row.
     /// </summary>
-    const cell_vector operator*() const;
+    const reference operator*() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
diff --git a/source/worksheet/range_iterator.cpp b/source/worksheet/range_iterator.cpp
index 57208d26..2c7a3a10 100644
--- a/source/worksheet/range_iterator.cpp
+++ b/source/worksheet/range_iterator.cpp
@@ -28,7 +28,12 @@
 
 namespace xlnt {
 
-cell_vector range_iterator::operator*() const
+range_iterator::reference range_iterator::operator*()
+{
+    return cell_vector(ws_, cursor_, bounds_, order_, skip_null_, false);
+}
+
+const range_iterator::reference range_iterator::operator*() const
 {
     return cell_vector(ws_, cursor_, bounds_, order_, skip_null_, false);
 }
@@ -264,7 +269,7 @@ const_range_iterator const_range_iterator::operator++(int)
     return old;
 }
 
-const cell_vector const_range_iterator::operator*() const
+const const_range_iterator::reference const_range_iterator::operator*() const
 {
     return cell_vector(ws_, cursor_, bounds_, order_, skip_null_, false);
 }

From 62e0a7dd178ae5c1b45d2524a6a0c926b65c2035 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:41:57 +1200
Subject: [PATCH 08/15] Revert "cell iterator - add operator->"

This reverts commit 1b705ae043ae1b43d0ecbc93da04c944383bb296.
---
 include/xlnt/worksheet/cell_iterator.hpp | 11 +----------
 source/worksheet/cell_iterator.cpp       | 16 ----------------
 2 files changed, 1 insertion(+), 26 deletions(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index 8dc53737..c6f1fa12 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -96,15 +96,6 @@ public:
     /// </summary>
     const reference operator*() const;
 
-    /// <summary>
-    /// Dereferences this iterator to return the cell it points to.
-    /// </summary>
-    reference operator->();
-
-    /// <summary>
-    /// Dereferences this iterator to return the cell it points to.
-    /// </summary>
-    const reference operator->() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
@@ -231,7 +222,7 @@ public:
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
-    const reference operator->() const;
+    const cell operator*() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
diff --git a/source/worksheet/cell_iterator.cpp b/source/worksheet/cell_iterator.cpp
index d1f66252..e4c334e9 100644
--- a/source/worksheet/cell_iterator.cpp
+++ b/source/worksheet/cell_iterator.cpp
@@ -279,20 +279,4 @@ const const_cell_iterator::reference const_cell_iterator::operator*() const
 {
     return ws_.cell(cursor_);
 }
-
-cell_iterator::reference cell_iterator::operator->()
-{
-    return operator*();
-}
-
-const cell_iterator::reference cell_iterator::operator->() const
-{
-    return operator*();
-}
-
-const const_cell_iterator::reference const_cell_iterator::operator->() const
-{
-    return operator*();
-}
-
 } // namespace xlnt

From eaf3c2a773d26337c52194273c13bc673e80dc1c Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:43:58 +1200
Subject: [PATCH 09/15] Remove double definition

---
 include/xlnt/worksheet/cell_iterator.hpp | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/include/xlnt/worksheet/cell_iterator.hpp b/include/xlnt/worksheet/cell_iterator.hpp
index c6f1fa12..415dee6f 100644
--- a/include/xlnt/worksheet/cell_iterator.hpp
+++ b/include/xlnt/worksheet/cell_iterator.hpp
@@ -219,11 +219,6 @@ public:
     /// </summary>
     const reference operator*() const;
 
-    /// <summary>
-    /// Dereferences this iterator to return the cell it points to.
-    /// </summary>
-    const cell operator*() const;
-
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
     /// </summary>

From a47985b2dbe76e624da8b0ef8a7e27542a849d92 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 15:56:07 +1200
Subject: [PATCH 10/15] worksheet_iterator - rule of 5/0

For rule of 5/0, where no implementation is required, all 5 operations have been declared as defaulted. This is less likely to forget definitions for all 5 if required
- removed forwarding of copy ctor to assignment (which was defaulted already) in favour of defaulted copy ctor
- added defaulted move assignment/ctor and destructor

Changed workbook reference to a pointer to allow tests to compile (reference isn't rebindable so defaulted assignment is equivalent to deleted)
---
 include/xlnt/workbook/worksheet_iterator.hpp | 42 +++++++++++++++++---
 source/workbook/worksheet_iterator.cpp       | 28 +++----------
 2 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/include/xlnt/workbook/worksheet_iterator.hpp b/include/xlnt/workbook/worksheet_iterator.hpp
index b2830f88..c1b24a78 100644
--- a/include/xlnt/workbook/worksheet_iterator.hpp
+++ b/include/xlnt/workbook/worksheet_iterator.hpp
@@ -61,12 +61,27 @@ public:
     /// <summary>
     /// Copy constructs a worksheet iterator from another iterator.
     /// </summary>
-    worksheet_iterator(const worksheet_iterator &);
+    worksheet_iterator(const worksheet_iterator &) = default;
 
     /// <summary>
     /// Assigns the iterator so that it points to the same worksheet in the same workbook.
     /// </summary>
-    worksheet_iterator &operator=(const worksheet_iterator &);
+    worksheet_iterator &operator=(const worksheet_iterator &) = default;
+
+    /// <summary>
+    /// Copy constructs a worksheet iterator from another iterator.
+    /// </summary>
+    worksheet_iterator(worksheet_iterator &&) = default;
+
+    /// <summary>
+    /// Assigns the iterator so that it points to the same worksheet in the same workbook.
+    /// </summary>
+    worksheet_iterator &operator=(worksheet_iterator &&) = default;
+
+    /// <summary>
+    /// Default destructor
+    /// </summary>
+    ~worksheet_iterator() = default;
 
     /// <summary>
     /// Dereferences the iterator to return the worksheet it is pointing to.
@@ -101,7 +116,7 @@ private:
     /// <summary>
     /// The target workbook of this iterator.
     /// </summary>
-    workbook &wb_;
+    workbook *wb_;
 
     /// <summary>
     /// The index of the worksheet in wb_ this iterator is currently pointing to.
@@ -133,12 +148,27 @@ public:
     /// <summary>
     /// Copy constructs a worksheet iterator from another iterator.
     /// </summary>
-    const_worksheet_iterator(const const_worksheet_iterator &);
+    const_worksheet_iterator(const const_worksheet_iterator &) = default;
 
     /// <summary>
     /// Assigns the iterator so that it points to the same worksheet in the same workbook.
     /// </summary>
-    const_worksheet_iterator &operator=(const const_worksheet_iterator &);
+    const_worksheet_iterator &operator=(const const_worksheet_iterator &) = default;
+
+    /// <summary>
+    /// Move constructs a worksheet iterator from another iterator.
+    /// </summary>
+    const_worksheet_iterator(const_worksheet_iterator &&) = default;
+
+    /// <summary>
+    /// Assigns the iterator from a temporary
+    /// </summary>
+    const_worksheet_iterator &operator=(const_worksheet_iterator &&) = default;
+
+    /// <summary>
+    /// Default destructor
+    /// </summary>
+    ~const_worksheet_iterator() = default;
 
     /// <summary>
     /// Dereferences the iterator to return the worksheet it is pointing to.
@@ -173,7 +203,7 @@ private:
     /// <summary>
     /// The target workbook of this iterator.
     /// </summary>
-    const workbook &wb_;
+    const workbook *wb_;
 
     /// <summary>
     /// The index of the worksheet in wb_ this iterator is currently pointing to.
diff --git a/source/workbook/worksheet_iterator.cpp b/source/workbook/worksheet_iterator.cpp
index daee7a64..0487cf33 100644
--- a/source/workbook/worksheet_iterator.cpp
+++ b/source/workbook/worksheet_iterator.cpp
@@ -28,18 +28,13 @@
 namespace xlnt {
 
 worksheet_iterator::worksheet_iterator(workbook &wb, std::size_t index)
-    : wb_(wb), index_(index)
-{
-}
-
-worksheet_iterator::worksheet_iterator(const worksheet_iterator &rhs)
-    : wb_(rhs.wb_), index_(rhs.index_)
+    : wb_(&wb), index_(index)
 {
 }
 
 worksheet worksheet_iterator::operator*()
 {
-    return wb_[index_];
+    return (*wb_)[index_];
 }
 
 worksheet_iterator &worksheet_iterator::operator++()
@@ -50,7 +45,7 @@ worksheet_iterator &worksheet_iterator::operator++()
 
 worksheet_iterator worksheet_iterator::operator++(int)
 {
-    worksheet_iterator old(wb_, index_);
+    worksheet_iterator old(*wb_, index_);
     ++*this;
     return old;
 }
@@ -65,25 +60,14 @@ bool worksheet_iterator::operator!=(const worksheet_iterator &comparand) const
     return !(*this == comparand);
 }
 
-worksheet_iterator &worksheet_iterator::operator=(const worksheet_iterator &other)
-{
-    index_ = other.index_;
-    return *this;
-}
-
 const_worksheet_iterator::const_worksheet_iterator(const workbook &wb, std::size_t index)
-    : wb_(wb), index_(index)
-{
-}
-
-const_worksheet_iterator::const_worksheet_iterator(const const_worksheet_iterator &rhs)
-    : wb_(rhs.wb_), index_(rhs.index_)
+    : wb_(&wb), index_(index)
 {
 }
 
 const worksheet const_worksheet_iterator::operator*()
 {
-    return wb_.sheet_by_index(index_);
+    return wb_->sheet_by_index(index_);
 }
 
 const_worksheet_iterator &const_worksheet_iterator::operator++()
@@ -94,7 +78,7 @@ const_worksheet_iterator &const_worksheet_iterator::operator++()
 
 const_worksheet_iterator const_worksheet_iterator::operator++(int)
 {
-    const_worksheet_iterator old(wb_, index_);
+    const_worksheet_iterator old(*wb_, index_);
     ++*this;
     return old;
 }

From 04b50d9b8ee5ee920f86209d3e972e8efcacd436 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Thu, 31 May 2018 16:00:40 +1200
Subject: [PATCH 11/15] worksheet_iterator - operator* const overloads

Users may still want to dereference a const iterator (note: not a const_iterator).
Also use the "reference" typedef to ensure there is only 1 source of information
---
 include/xlnt/workbook/worksheet_iterator.hpp | 11 +++++++++--
 source/workbook/worksheet_iterator.cpp       |  9 +++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/include/xlnt/workbook/worksheet_iterator.hpp b/include/xlnt/workbook/worksheet_iterator.hpp
index c1b24a78..444b792f 100644
--- a/include/xlnt/workbook/worksheet_iterator.hpp
+++ b/include/xlnt/workbook/worksheet_iterator.hpp
@@ -88,7 +88,14 @@ public:
     /// If the iterator points to one-past-the-end of the workbook, an invalid_parameter
     /// exception will be thrown.
     /// </summary>
-    worksheet operator*();
+    reference operator*();
+
+    /// <summary>
+    /// Dereferences the iterator to return the worksheet it is pointing to.
+    /// If the iterator points to one-past-the-end of the workbook, an invalid_parameter
+    /// exception will be thrown.
+    /// </summary>
+    const reference operator*() const;
 
     /// <summary>
     /// Returns true if this iterator points to the same worksheet as comparand.
@@ -175,7 +182,7 @@ public:
     /// If the iterator points to one-past-the-end of the workbook, an invalid_parameter
     /// exception will be thrown.
     /// </summary>
-    const worksheet operator*();
+    const reference operator*() const;
 
     /// <summary>
     /// Returns true if this iterator points to the same worksheet as comparand.
diff --git a/source/workbook/worksheet_iterator.cpp b/source/workbook/worksheet_iterator.cpp
index 0487cf33..3c981339 100644
--- a/source/workbook/worksheet_iterator.cpp
+++ b/source/workbook/worksheet_iterator.cpp
@@ -32,7 +32,12 @@ worksheet_iterator::worksheet_iterator(workbook &wb, std::size_t index)
 {
 }
 
-worksheet worksheet_iterator::operator*()
+worksheet_iterator::reference worksheet_iterator::operator*()
+{
+    return (*wb_)[index_];
+}
+
+const worksheet_iterator::reference worksheet_iterator::operator*() const
 {
     return (*wb_)[index_];
 }
@@ -65,7 +70,7 @@ const_worksheet_iterator::const_worksheet_iterator(const workbook &wb, std::size
 {
 }
 
-const worksheet const_worksheet_iterator::operator*()
+const const_worksheet_iterator::reference const_worksheet_iterator::operator*() const
 {
     return wb_->sheet_by_index(index_);
 }

From b95919323d779f99096705520e48602933d113b3 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Sat, 9 Jun 2018 11:57:45 +1200
Subject: [PATCH 12/15] add more tests for worksheet iterator, add operator--

* operator-- completes the naive bidirectional iterator requirements
* tests for various construction and assignment behaviours
* tests for iteration and dereferencing behaviours
---
 include/xlnt/workbook/worksheet_iterator.hpp | 24 +++++++
 source/workbook/worksheet_iterator.cpp       | 26 +++++++
 tests/workbook/workbook_test_suite.hpp       | 76 ++++++++++++++++++--
 3 files changed, 122 insertions(+), 4 deletions(-)

diff --git a/include/xlnt/workbook/worksheet_iterator.hpp b/include/xlnt/workbook/worksheet_iterator.hpp
index 444b792f..f575dc7c 100644
--- a/include/xlnt/workbook/worksheet_iterator.hpp
+++ b/include/xlnt/workbook/worksheet_iterator.hpp
@@ -119,6 +119,18 @@ public:
     /// </summary>
     worksheet_iterator &operator++();
 
+    /// <summary>
+    /// Post-decrement the iterator's internal workseet index. Returns a copy of the
+    /// iterator as it was before being incremented.
+    /// </summary>
+    worksheet_iterator operator--(int);
+
+    /// <summary>
+    /// Pre-decrement the iterator's internal workseet index. Returns a refernce
+    /// to the same iterator.
+    /// </summary>
+    worksheet_iterator &operator--();
+
 private:
     /// <summary>
     /// The target workbook of this iterator.
@@ -206,6 +218,18 @@ public:
     /// </summary>
     const_worksheet_iterator &operator++();
 
+    /// <summary>
+    /// Post-decrement the iterator's internal workseet index. Returns a copy of the
+    /// iterator as it was before being incremented.
+    /// </summary>
+    const_worksheet_iterator operator--(int);
+
+    /// <summary>
+    /// Pre-decrement the iterator's internal workseet index. Returns a refernce
+    /// to the same iterator.
+    /// </summary>
+    const_worksheet_iterator &operator--();
+
 private:
     /// <summary>
     /// The target workbook of this iterator.
diff --git a/source/workbook/worksheet_iterator.cpp b/source/workbook/worksheet_iterator.cpp
index 3c981339..b1432e33 100644
--- a/source/workbook/worksheet_iterator.cpp
+++ b/source/workbook/worksheet_iterator.cpp
@@ -55,6 +55,19 @@ worksheet_iterator worksheet_iterator::operator++(int)
     return old;
 }
 
+worksheet_iterator &worksheet_iterator::operator--()
+{
+    --index_;
+    return *this;
+}
+
+worksheet_iterator worksheet_iterator::operator--(int)
+{
+    worksheet_iterator old(*wb_, index_);
+    --(*this);
+    return old;
+}
+
 bool worksheet_iterator::operator==(const worksheet_iterator &comparand) const
 {
     return index_ == comparand.index_ && wb_ == comparand.wb_;
@@ -88,6 +101,19 @@ const_worksheet_iterator const_worksheet_iterator::operator++(int)
     return old;
 }
 
+const_worksheet_iterator &const_worksheet_iterator::operator--()
+{
+    --index_;
+    return *this;
+}
+
+const_worksheet_iterator const_worksheet_iterator::operator--(int)
+{
+    const_worksheet_iterator old(*wb_, index_);
+    --(*this);
+    return old;
+}
+
 bool const_worksheet_iterator::operator==(const const_worksheet_iterator &comparand) const
 {
     return index_ == comparand.index_ && wb_ == comparand.wb_;
diff --git a/tests/workbook/workbook_test_suite.hpp b/tests/workbook/workbook_test_suite.hpp
index cbd4bda3..8a69a9cd 100644
--- a/tests/workbook/workbook_test_suite.hpp
+++ b/tests/workbook/workbook_test_suite.hpp
@@ -45,6 +45,7 @@ public:
         register_test(test_index_operator);
         register_test(test_contains);
         register_test(test_iter);
+        register_test(test_const_iter);
         register_test(test_get_index);
         register_test(test_get_sheet_names);
         register_test(test_add_named_range);
@@ -153,17 +154,84 @@ public:
         xlnt_assert(wb.contains("Sheet1"));
         xlnt_assert(!wb.contains("NotThere"));
     }
-    
+
     void test_iter()
     {
         xlnt::workbook wb;
-        
-        for(auto ws : wb)
+
+        for (auto ws : wb)
         {
             xlnt_assert_equals(ws.title(), "Sheet1");
         }
+
+        xlnt::workbook wb2;
+        auto iter = wb.begin();
+        auto iter_copy(iter); // copy ctor
+        xlnt_assert_equals(iter, iter_copy);
+        auto begin_2(wb2.begin());
+        xlnt_assert_differs(begin_2, iter);
+        iter = begin_2; // copy assign
+        xlnt_assert_equals(iter, begin_2);
+        iter = wb.begin();
+        iter = std::move(begin_2);
+        xlnt_assert_equals(iter, wb2.begin());
+
+        auto citer = wb.cbegin();
+        auto citer_copy(citer); // copy ctor
+        xlnt_assert_equals(citer, citer_copy);
+        auto cbegin_2(wb2.cbegin());
+        xlnt_assert_differs(cbegin_2, citer);
+        citer = cbegin_2; // copy assign
+        xlnt_assert_equals(citer, cbegin_2);
+        citer = wb.cbegin();
+        citer = std::move(cbegin_2);
+        xlnt_assert_equals(citer, wb2.cbegin());
+
+        wb2.create_sheet(); // wb2 iterators assumed invalidated
+        iter = wb2.begin();
+        xlnt_assert_equals((*iter).title(), "Sheet1");
+        ++iter;
+        xlnt_assert_differs(iter, wb2.begin());
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        --iter;
+        xlnt_assert_equals((*iter).title(), "Sheet1");
+        std::advance(iter, 2);
+        xlnt_assert_equals(iter, wb2.end());
     }
-    
+
+    void test_const_iter()
+    {
+        const xlnt::workbook wb;
+
+        for (auto ws : wb)
+        {
+            xlnt_assert_equals(ws.title(), "Sheet1");
+        }
+
+        xlnt::workbook wb2;
+        auto iter = wb.cbegin();
+        auto iter_copy(iter); // copy ctor
+        xlnt_assert_equals(iter, iter_copy);
+        auto begin_2(wb2.cbegin());
+        xlnt_assert_differs(begin_2, iter);
+        iter = begin_2; // copy assign
+        xlnt_assert_equals(iter, begin_2);
+        iter = wb.cbegin();
+        iter = std::move(begin_2);
+        xlnt_assert_equals(iter, wb2.cbegin());
+
+        wb2.create_sheet(); // wb2 iterators assumed invalidated
+        iter = wb2.cbegin();
+        xlnt_assert_equals((*iter).title(), "Sheet1");
+        ++iter;
+        xlnt_assert_differs(iter, wb2.cbegin());
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        --iter;
+        xlnt_assert_equals((*iter).title(), "Sheet1");
+        std::advance(iter, 2);
+        xlnt_assert_equals(iter, wb2.cend());
+    }
+
     void test_get_index()
     {
         xlnt::workbook wb;

From 9a82c4fab715f801173813e91c37d36863398438 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Sat, 9 Jun 2018 12:39:58 +1200
Subject: [PATCH 13/15] Comment fixes and clarifications

---
 include/xlnt/workbook/worksheet_iterator.hpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/xlnt/workbook/worksheet_iterator.hpp b/include/xlnt/workbook/worksheet_iterator.hpp
index f575dc7c..3e0165fb 100644
--- a/include/xlnt/workbook/worksheet_iterator.hpp
+++ b/include/xlnt/workbook/worksheet_iterator.hpp
@@ -64,17 +64,17 @@ public:
     worksheet_iterator(const worksheet_iterator &) = default;
 
     /// <summary>
-    /// Assigns the iterator so that it points to the same worksheet in the same workbook.
+    /// Copy assigns the iterator so that it points to the same worksheet in the same workbook.
     /// </summary>
     worksheet_iterator &operator=(const worksheet_iterator &) = default;
 
     /// <summary>
-    /// Copy constructs a worksheet iterator from another iterator.
+    /// Move constructs a worksheet iterator from a temporary iterator.
     /// </summary>
     worksheet_iterator(worksheet_iterator &&) = default;
 
     /// <summary>
-    /// Assigns the iterator so that it points to the same worksheet in the same workbook.
+    /// Move assign the iterator from a temporary iterator
     /// </summary>
     worksheet_iterator &operator=(worksheet_iterator &&) = default;
 
@@ -170,17 +170,17 @@ public:
     const_worksheet_iterator(const const_worksheet_iterator &) = default;
 
     /// <summary>
-    /// Assigns the iterator so that it points to the same worksheet in the same workbook.
+    /// Copy assigns the iterator so that it points to the same worksheet in the same workbook.
     /// </summary>
     const_worksheet_iterator &operator=(const const_worksheet_iterator &) = default;
 
     /// <summary>
-    /// Move constructs a worksheet iterator from another iterator.
+    /// Move constructs a worksheet iterator from a temporary iterator.
     /// </summary>
     const_worksheet_iterator(const_worksheet_iterator &&) = default;
 
     /// <summary>
-    /// Assigns the iterator from a temporary
+    /// Move assigns the iterator from a temporary iterator
     /// </summary>
     const_worksheet_iterator &operator=(const_worksheet_iterator &&) = default;
 

From 4afc0963c6af750db1bb75c2f74372f772846282 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Sat, 9 Jun 2018 12:49:54 +1200
Subject: [PATCH 14/15] add post (in/de)crement tests

---
 tests/workbook/workbook_test_suite.hpp | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/tests/workbook/workbook_test_suite.hpp b/tests/workbook/workbook_test_suite.hpp
index 8a69a9cd..531ca22c 100644
--- a/tests/workbook/workbook_test_suite.hpp
+++ b/tests/workbook/workbook_test_suite.hpp
@@ -193,10 +193,18 @@ public:
         ++iter;
         xlnt_assert_differs(iter, wb2.begin());
         xlnt_assert_equals((*iter).title(), "Sheet2");
-        --iter;
+        auto temp = --iter;
+        xlnt_assert_equals((*temp).title(), "Sheet1");
         xlnt_assert_equals((*iter).title(), "Sheet1");
-        std::advance(iter, 2);
+        iter++;
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        temp = iter++;
+        xlnt_assert_equals((*temp).title(), "Sheet2");
         xlnt_assert_equals(iter, wb2.end());
+
+        iter = temp--;
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        xlnt_assert_equals((*temp).title(), "Sheet1");
     }
 
     void test_const_iter()
@@ -226,10 +234,18 @@ public:
         ++iter;
         xlnt_assert_differs(iter, wb2.cbegin());
         xlnt_assert_equals((*iter).title(), "Sheet2");
-        --iter;
+        auto temp = --iter;
+        xlnt_assert_equals((*temp).title(), "Sheet1");
         xlnt_assert_equals((*iter).title(), "Sheet1");
-        std::advance(iter, 2);
+        iter++;
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        temp = iter++;
+        xlnt_assert_equals((*temp).title(), "Sheet2");
         xlnt_assert_equals(iter, wb2.cend());
+
+        iter = temp--;
+        xlnt_assert_equals((*iter).title(), "Sheet2");
+        xlnt_assert_equals((*temp).title(), "Sheet1");
     }
 
     void test_get_index()

From cffb1ce3452b9ce8738bd28b8d1153dea0996d00 Mon Sep 17 00:00:00 2001
From: Crzyrndm <joshcrawfy@gmail.com>
Date: Tue, 10 Jul 2018 14:12:26 +1200
Subject: [PATCH 15/15] restart CI

---
 tests/workbook/workbook_test_suite.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/workbook/workbook_test_suite.hpp b/tests/workbook/workbook_test_suite.hpp
index 531ca22c..e85a7a7e 100644
--- a/tests/workbook/workbook_test_suite.hpp
+++ b/tests/workbook/workbook_test_suite.hpp
@@ -227,8 +227,8 @@ public:
         iter = wb.cbegin();
         iter = std::move(begin_2);
         xlnt_assert_equals(iter, wb2.cbegin());
-
-        wb2.create_sheet(); // wb2 iterators assumed invalidated
+        // wb2 iterators assumed invalidated
+        wb2.create_sheet();
         iter = wb2.cbegin();
         xlnt_assert_equals((*iter).title(), "Sheet1");
         ++iter;