Implement case statements

boot/symbol.cc

@@ -292,6 +292,16 @@ namespace elna::boot
         return nullptr;
     }
 
+    std::shared_ptr<constant_info> info::is_constant()
+    {
+        return nullptr;
+    }
+
+    std::shared_ptr<variable_info> info::is_variable()
+    {
+        return nullptr;
+    }
+
     type_info::type_info(const type symbol)
         : symbol(symbol)
     {
@@ -317,6 +327,21 @@ namespace elna::boot
     {
     }
 
+    std::shared_ptr<constant_info> constant_info::is_constant()
+    {
+        return std::static_pointer_cast<constant_info>(shared_from_this());
+    }
+
+    variable_info::variable_info(const std::string& name, const type symbol)
+        : name(name), symbol(symbol)
+    {
+    }
+
+    std::shared_ptr<variable_info> variable_info::is_variable()
+    {
+        return std::static_pointer_cast<variable_info>(shared_from_this());;
+    }
+
     std::shared_ptr<symbol_table> builtin_symbol_table()
     {
         auto result = std::make_shared<symbol_table>();