Simplify unescape_c.

Author: ColinH

include/tao/pegtl/extra/unescape.hpp

@@ -36,21 +36,17 @@ namespace TAO_PEGTL_NAMESPACE::unescape
       }
    };
 
-   // The unescape_c action MUST be called for a character matching One which MUST
-   // be, or publicly derive from, TAO_PEGTL_NAMESPACE::ascii::one< ... >.
-
-   template< typename One, char... Rs >
+   template< char... Rs >
    struct unescape_c
    {
-      using one_t = typename One::test_t;
-
       static_assert( sizeof...( Rs ) > 0 );
 
-      template< typename ActionInput >
+      template< typename One, typename ActionInput >
       static void apply( const ActionInput& in, std::string& s )
       {
          // assert( in.size() == 1 );
-         s += apply_one( in.peek_char(), one_t() );
+         using test_t = typename One::test_t;
+         s += apply_one( in.peek_char(), test_t() );
       }
 
    private:

src/example/json_unescape.hpp

@@ -21,7 +21,7 @@ namespace example
    template< typename Rule > struct json_unescape_action {};
 
    template<> struct json_unescape_action< pegtl::json::unicode > : pegtl::unescape::unescape_j {};
-   template<> struct json_unescape_action< pegtl::json::escaped_char > : pegtl::unescape::unescape_c< pegtl::json::escaped_char, '"', '\\', '/', '\b', '\f', '\n', '\r', '\t' > {};
+   template<> struct json_unescape_action< pegtl::json::escaped_char > : pegtl::unescape::unescape_c< '"', '\\', '/', '\b', '\f', '\n', '\r', '\t' > {};
    template<> struct json_unescape_action< pegtl::json::unescaped > : pegtl::unescape::append_all {};
    // clang-format on
 

src/example/unescape.cpp

@@ -43,7 +43,7 @@ namespace example
    template<> struct action< escaped_x > : unescape::unescape_x {};
    template<> struct action< escaped_u > : unescape::unescape_u {};
    template<> struct action< escaped_U > : unescape::unescape_u {};
-   template<> struct action< escaped_c > : unescape::unescape_c< escaped_c, '\'', '"', '?', '\\', '\a', '\b', '\f', '\n', '\r', '\t', '\v' > {};
+   template<> struct action< escaped_c > : unescape::unescape_c< '\'', '"', '?', '\\', '\a', '\b', '\f', '\n', '\r', '\t', '\v' > {};
    // clang-format on
 
 }  // namespace example

src/test/extra_unescape.cpp

@@ -21,7 +21,7 @@ namespace TAO_PEGTL_NAMESPACE
 
    template< typename Rule > struct unaction {};
 
-   template<> struct unaction< escaped_c > : unescape::unescape_c< escaped_c, '"', '\\', '\t' > {};
+   template<> struct unaction< escaped_c > : unescape::unescape_c< '"', '\\', '\t' > {};
    template<> struct unaction< escaped_u > : unescape::unescape_u {};
    template<> struct unaction< escaped_U > : unescape::unescape_u {};
    template<> struct unaction< escaped_j > : unescape::unescape_j {};