Remove all explicitly typed for loops.

src/Range.hpp

@@ -2,6 +2,14 @@
 
 namespace fmri
 {
+
+    /**
+     * Iterable that produces a specific range of integers.
+     *
+     * Useful to make an automatically typed for loop over an unknown integer type.
+     *
+     * @tparam T The integer type to use.
+     */
     template<class T>
     class Range
     {
@@ -10,9 +18,20 @@ namespace fmri
         T end_;
 
     public:
-        explicit Range(const T &num) : start_(0), end_(num) {};
+        /**
+         * Construct a range from 0 to num, non inclusive.
+         *
+         * @param num
+         */
+        constexpr explicit Range(const T &num) : start_(0), end_(num) {};
 
-        Range(const T &start, const T &end) : start_(start), end_(end) {};
+        /**
+         * Construct a range from start to end, non inclusive.
+         *
+         * @param start
+         * @param end
+         */
+        constexpr Range(const T &start, const T &end) : start_(start), end_(end) {};
 
         class Iter
         {
@@ -20,18 +39,28 @@ namespace fmri
             T cur_;
 
         public:
-            explicit Iter(const T &cur) : cur_(cur)
+            constexpr explicit Iter(const T &cur) : cur_(cur)
             {};
 
-            bool operator!=(const Iter& o) { return o.cur_ != cur_; }
-            Iter&operator++() { ++cur_; return *this; }
+            typedef std::bidirectional_iterator_tag iterator_category;
+            typedef T value_type;
+            typedef typename std::make_signed<T>::type difference_type;
+            typedef T& reference;
+            typedef T* pointer;
 
-            T &operator*() { return cur_; }
+            constexpr bool operator!=(const Iter& o) { return o.cur_ != cur_; }
+            constexpr Iter&operator++() { ++cur_; return *this; }
+            constexpr Iter&operator--() { --cur_; return *this; }
+
+            constexpr const T &operator*() { return cur_; }
         };
 
         typedef Iter const_iterator;
+        typedef std::reverse_iterator<Iter> const_reverse_iterator;
 
-        const_iterator begin() const { return Iter(start_); }
-        const_iterator end() const { return Iter(end_); }
+        constexpr const_iterator begin() const { return Iter(start_); }
+        constexpr const_iterator end() const { return Iter(end_); }
+        constexpr const_reverse_iterator rbegin() const { return std::make_reverse_iterator(end()); }
+        constexpr const_reverse_iterator rend() const { return std::make_reverse_iterator(begin()); }
     };
-}
+}