Implement character escape sequences

include/elna/source/ast.h

@@ -736,7 +736,7 @@ namespace source
 
     public:
         unary_expression(const struct position position, expression *operand,
-                const unsigned char operation);
+                const unary_operator operation);
 
         virtual void accept(parser_visitor *visitor) override;
         expression& operand();

include/elna/source/symbol.h

@@ -41,6 +41,8 @@ namespace source
     {
     public:
         using symbol_ptr = std::shared_ptr<info<T>>;
+        using iterator = typename std::unordered_map<std::string, symbol_ptr>::iterator;
+        using const_iterator = typename std::unordered_map<std::string, symbol_ptr>::const_iterator;
 
     private:
         std::unordered_map<std::string, symbol_ptr> entries;
@@ -57,6 +59,26 @@ namespace source
         {
         }
 
+        iterator begin()
+        {
+            return entries.begin();
+        }
+
+        iterator end()
+        {
+            return entries.end();
+        }
+
+        const_iterator cbegin() const
+        {
+            return entries.cbegin();
+        }
+
+        const_iterator cend() const
+        {
+            return entries.cend();
+        }
+
         /**
          * Looks for symbol in the table by name. Returns nullptr if the symbol
          * can not be found.