Implement defer

boot/driver.cc

@@ -9,10 +9,11 @@ namespace boot
 {
     position make_position(const yy::location& location)
     {
-        return position{
-            static_cast<std::size_t>(location.begin.line),
-            static_cast<std::size_t>(location.begin.column)
-        };
+        position result;
+        result.line = static_cast<std::size_t>(location.begin.line);
+        result.column = static_cast<std::size_t>(location.begin.column);
+
+        return result;
     }
 
     syntax_error::syntax_error(const std::string& message,
@@ -33,7 +34,7 @@ namespace boot
 
     void driver::error(const yy::location& loc, const std::string& message)
     {
-        m_errors.emplace_back(std::make_unique<boot::syntax_error>(message, input_file, loc));
+        m_errors.emplace_back(new boot::syntax_error(message, input_file, loc));
     }
 
     const std::list<std::unique_ptr<struct error>>& driver::errors() const noexcept
@@ -41,36 +42,36 @@ namespace boot
         return m_errors;
     }
 
-    std::optional<char> escape_char(char escape)
+    char escape_char(char escape)
     {
         switch (escape)
         {
         case 'n':
-            return std::make_optional<char>('\n');
+            return '\n';
         case 'a':
-            return std::make_optional<char>('\a');
+            return '\a';
         case 'b':
-            return std::make_optional<char>('\b');
+            return '\b';
         case 't':
-            return std::make_optional<char>('\t');
+            return '\t';
         case 'f':
-            return std::make_optional<char>('\f');
+            return '\f';
         case 'r':
-            return std::make_optional<char>('\r');
+            return '\r';
         case 'v':
-            return std::make_optional<char>('\v');
+            return '\v';
         case '\\':
-            return std::make_optional<char>('\\');
+            return '\\';
         case '\'':
-            return std::make_optional<char>('\'');
+            return '\'';
         case '"':
-            return std::make_optional<char>('"');
+            return '"';
         case '?':
-            return std::make_optional<char>('\?');
+            return '\?';
         case '0':
-            return std::make_optional<char>('\0');
+            return '\0';
         default:
-            return std::nullopt;
+            return escape_invalid_char;
         }
     }
 }