Contrib instantiate.

include/tao/pegtl/contrib/instantiate.hpp

@@ -0,0 +1,38 @@
+// Copyright (c) 2020 Dr. Colin Hirsch and Daniel Frey
+// Please see LICENSE for license or visit https://github.com/taocpp/PEGTL/
+
+#ifndef TAO_PEGTL_CONTRIB_INSTANTIATE_HPP
+#define TAO_PEGTL_CONTRIB_INSTANTIATE_HPP
+
+#include "../config.hpp"
+
+#include "../apply_mode.hpp"
+#include "../match.hpp"
+#include "../nothing.hpp"
+#include "../rewind_mode.hpp"
+
+namespace TAO_PEGTL_NAMESPACE
+{
+   template< typename T >
+   struct instantiate
+      : maybe_nothing
+   {
+      template< typename Rule,
+                apply_mode A,
+                rewind_mode M,
+                template< typename... >
+                class Action,
+                template< typename... >
+                class Control,
+                typename ParseInput,
+                typename... States >
+      [[nodiscard]] static bool match( ParseInput& in, States&... st )
+      {
+         const T t( static_cast< const ParseInput& >( in ), st... );
+         return TAO_PEGTL_NAMESPACE::match< Rule, A, M, Action, Control >( in, st... );
+      }
+   };
+
+}  // namespace TAO_PEGTL_NAMESPACE
+
+#endif

src/test/pegtl/CMakeLists.txt

@@ -30,6 +30,7 @@ set(test_sources
   contrib_function.cpp
   contrib_http.cpp
   contrib_if_then.cpp
+  contrib_instantiate.cpp
   contrib_integer.cpp
   contrib_json.cpp
   contrib_parse_tree.cpp

src/test/pegtl/contrib_instantiate.cpp

@@ -0,0 +1,72 @@
+// Copyright (c) 2020 Dr. Colin Hirsch and Daniel Frey
+// Please see LICENSE for license or visit https://github.com/taocpp/PEGTL/
+
+#include "test.hpp"
+
+#include <tao/pegtl/contrib/instantiate.hpp>
+
+namespace TAO_PEGTL_NAMESPACE
+{
+   bool ctor = false;
+   bool dtor = false;
+
+   struct test_class
+   {
+      template< typename ParseInput >
+      test_class( const ParseInput& /*unused*/ )
+      {
+         TAO_PEGTL_TEST_ASSERT( ctor == false );
+         TAO_PEGTL_TEST_ASSERT( dtor == false );
+
+         ctor = true;
+      }
+
+      test_class( test_class&& ) = delete;
+      test_class( const test_class& ) = delete;
+
+      ~test_class()
+      {
+         TAO_PEGTL_TEST_ASSERT( ctor == true );
+         TAO_PEGTL_TEST_ASSERT( dtor == false );
+
+         dtor = true;
+      }
+
+      void operator=( test_class&& ) = delete;
+      void operator=( const test_class& ) = delete;
+   };
+
+   using test_grammar = must< sor< alpha, digit > >;
+
+   template< typename Rule >
+   struct test_action
+      : nothing< Rule >
+   {};
+
+   template<>
+   struct test_action< alpha >
+   {
+      static void apply0()
+      {
+         TAO_PEGTL_TEST_ASSERT( ctor == true );
+         TAO_PEGTL_TEST_ASSERT( dtor == false );
+      }
+   };
+
+   template<>
+   struct test_action< sor< alpha, digit > >
+      : instantiate< test_class >
+   {};
+
+   void unit_test()
+   {
+      memory_input in( "a", __FUNCTION__ );
+      parse< test_grammar, test_action >( in );
+
+      TAO_PEGTL_TEST_ASSERT( ctor == true );
+      TAO_PEGTL_TEST_ASSERT( dtor == true );
+   }
+
+}  // namespace TAO_PEGTL_NAMESPACE
+
+#include "main.hpp"