Issue #3, changes in the operator + of the iterator class (#4)

* Add n + it operator in iterator class

* Remove it + it operator in the iterator class

* Change tab to space as indentation

* Add tests for arithmetic operations on RandomAccessIterator.

src/ordered_map.h

@@ -281,14 +281,15 @@ class ordered_hash {
         friend bool operator>=(const ordered_iterator& lhs, const ordered_iterator& rhs) { 
             return lhs.m_iterator >= rhs.m_iterator; 
         }
-        
-        friend difference_type operator+(const ordered_iterator& lhs, const ordered_iterator& rhs) { 
-            return lhs.m_iterator + rhs.m_iterator; 
+
+        friend ordered_iterator operator+(difference_type n, const ordered_iterator& it) { 
+            return n + it.m_iterator;
         }
-        
+
         friend difference_type operator-(const ordered_iterator& lhs, const ordered_iterator& rhs) { 
             return lhs.m_iterator - rhs.m_iterator; 
         }
+
     private:
         iterator m_iterator;
     };

tests/ordered_map_tests.cpp

@@ -269,6 +269,54 @@ BOOST_AUTO_TEST_CASE(test_reverse_iterator) {
     }
 }
 
+BOOST_AUTO_TEST_CASE(test_iterator_arithmetic) {
+    tsl::ordered_map<int64_t, int64_t> map = {{1, 10}, {2, 20}, {3, 30}, 
+                                              {4, 40}, {5, 50}, {6, 60}};
+
+    tsl::ordered_map<int64_t, int64_t>::const_iterator it;
+    tsl::ordered_map<int64_t, int64_t>::const_iterator it2;
+
+    it = map.cbegin();
+    // it += n
+    it += 3;
+    BOOST_CHECK_EQUAL(it->second, 40);
+
+
+
+    // it + n
+    BOOST_CHECK_EQUAL((map.cbegin() + 3)->second, 40);
+    // n + it
+    BOOST_CHECK_EQUAL((3 + map.cbegin())->second, 40);
+
+
+
+    it = map.cbegin() + 4;
+    // it -= n
+    it -= 2;
+    BOOST_CHECK_EQUAL(it->second, 30);
+
+
+
+    // it - n
+    BOOST_CHECK_EQUAL((it - 1)->second, 20);
+
+
+
+    it = map.cbegin() + 2;
+    it2 = map.cbegin() + 4;
+    // it - it
+    BOOST_CHECK_EQUAL(it2 - it, 2);
+
+
+
+    // it[n]
+    BOOST_CHECK_EQUAL(map.cbegin()[2].second, 30);
+
+    it = map.cbegin() + 1;
+    // it[n]
+    BOOST_CHECK_EQUAL(it[2].second, 40);
+}
+
 /**
  * operator=
  */
@@ -316,7 +364,6 @@ BOOST_AUTO_TEST_CASE(test_move) {
 }
 
 
-
 /**
  * at
  */