improve o3tl::enumarray const-ness

Change-Id: I7b0d10b024edf604a7dea0e3b1399073f4bcba92
Reviewed-on: https://gerrit.libreoffice.org/43773
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 45 insertions, 11 deletions

diff --git a/include/o3tl/enumarray.hxx b/include/o3tl/enumarray.hxx
index 766d9670b34a..ca012e197f27 100644
--- a/include/o3tl/enumarray.hxx
+++ b/include/o3tl/enumarray.hxx
@@ -28,6 +28,8 @@ namespace o3tl {
 
 template<typename EA>
 class enumarray_iterator;
+template<typename EA>
+class enumarray_const_iterator;
 
 ///
 /// This is a container convenience class for arrays indexed by enum values.
@@ -45,6 +47,7 @@ class enumarray final
 public:
     typedef enumarray<E, V> self_type;
     typedef enumarray_iterator<self_type> iterator;
+    typedef enumarray_const_iterator<self_type> const_iterator;
 
     typedef V             value_type;
     typedef E             key_type;
@@ -67,11 +70,13 @@ public:
     void fill(V val)
     { for (size_type i=0; i<=max_index; ++i) detail_values[i] = val; }
 
-    static size_type size() { return max_index + 1; }
-    iterator  begin()      { return iterator(*this, 0); }
-    iterator  end()        { return iterator(*this, size()); }
+    static size_type size()        { return max_index + 1; }
+    iterator         begin()       { return iterator(*this, 0); }
+    iterator         end()         { return iterator(*this, size()); }
+    const_iterator   begin() const { return const_iterator(*this, 0); }
+    const_iterator   end() const   { return const_iterator(*this, size()); }
 
-    V*        data()       { return detail_values; }
+    V*               data()       { return detail_values; }
 
 //private:
     V detail_values[max_index + 1];
@@ -80,7 +85,7 @@ public:
 
 template<typename EA>
 class enumarray_iterator {
-    EA         *m_buf;
+    EA&         m_buf;
     size_t      m_pos;
 public:
     typedef enumarray_iterator<EA>  self_type;
@@ -95,12 +100,41 @@ public:
     typedef typename EA::value_type&   reference;
 
     enumarray_iterator(EA& b, size_t start_pos)
-         : m_buf(&b), m_pos(start_pos) {}
-    value_type &operator*()  { return (*m_buf)[static_cast<key_type>(m_pos)]; }
-    value_type *operator->() { return &(operator*()); }
-    self_type  &operator++() { ++m_pos; return *this; }
-    bool        operator!=(const self_type& other) const { return m_buf != other.m_buf || m_pos != other.m_pos; }
-    bool        operator==(const self_type& other) const { return m_buf == other.m_buf && m_pos == other.m_pos; }
+         : m_buf(b), m_pos(start_pos) {}
+    value_type& operator*()  const { return m_buf[static_cast<key_type>(m_pos)]; }
+    value_type* operator->() const { return &(operator*()); }
+    self_type&  operator++() { ++m_pos; return *this; }
+    bool        operator!=(self_type const & other) const { return &m_buf != &other.m_buf || m_pos != other.m_pos; }
+    bool        operator==(self_type const & other) const { return &m_buf == &other.m_buf && m_pos == other.m_pos; }
+    enumarray_iterator&
+                operator=(self_type const & other) { m_buf = other.m_buf; m_pos = other.m_pos; return *this; }
+};
+
+template<typename EA>
+class enumarray_const_iterator {
+    EA const &  m_buf;
+    size_t      m_pos;
+public:
+    typedef enumarray_const_iterator<EA>    self_type;
+    typedef typename EA::value_type const   value_type;
+    typedef typename EA::key_type           key_type;
+    typedef std::bidirectional_iterator_tag iterator_category; //should be random access, but that would require define subtraction operators on the enums
+    typedef
+        typename std::make_signed<
+            typename std::underlying_type<typename EA::key_type>::type>::type
+                                            difference_type;
+    typedef typename EA::value_type const * pointer;
+    typedef typename EA::value_type const & reference;
+
+    enumarray_const_iterator(EA const & b, size_t start_pos)
+         : m_buf(b), m_pos(start_pos) {}
+    value_type& operator*()  const { return m_buf[static_cast<key_type>(m_pos)]; }
+    value_type* operator->() const { return &(operator*()); }
+    self_type&  operator++() { ++m_pos; return *this; }
+    bool        operator!=(self_type const & other) const { return &m_buf != &other.m_buf || m_pos != other.m_pos; }
+    bool        operator==(self_type const & other) const { return &m_buf == &other.m_buf && m_pos == other.m_pos; }
+    enumarray_const_iterator&
+                operator=(self_type const & other) { m_buf = other.m_buf; m_pos = other.m_pos; return *this; }
 };
 
 }; // namespace o3tl