xo-reader2: + DExpectTypeSsm [WIP] [NOBUILD]

xo-reader2/include/xo/reader2/DExpectTypeSsm.hpp

@@ -0,0 +1,64 @@
+/** @file expect_type_xs.hpp
+ *
+ * @author Roland Conybeare, Aug 2024
+ **/
+
+#pragma once
+
+#include "SyntaxStateMachine.hpp"
+
+namespace xo {
+    namespace scm {
+        /** @class DExpectTypeSsm
+         *  @brief syntax state-machine for accepting a Schemtika typename-expression
+         *
+         *  Jan 2026
+         *  Placeholder implementation at present.
+         *  Only types are a handful of baked-in values
+         *
+         *  @pre
+         *
+         *  @endpre
+         **/
+        class DExpectTypeSsm {
+        public:
+            DExpectTypeSsm();
+
+            static DExpectTypeSsm * make(DArena & parser_mm);
+
+            static void start(DArena & parser_mm,
+                              //obj<AAllocator> expr_mm,
+                              ParserStateMachine * p_psm);
+
+            virtual const char * get_expect_str() const override;
+
+            virtual void on_symbol_token(const token_type & tk,
+                                         parserstatemachine * p_psm) override;
+
+            /** @defgroup scm-expecttype-ssm-facet syntaxstatemachine facet methods **/
+            ///@{
+
+            /** identifies the ssm implemented here **/
+            syntaxstatetype ssm_type() const noexcept;
+
+            /** text describing expected/allowed input to this ssm in current state.
+             *  Intended to drive error messages.
+             **/
+            std::string_view get_expect_str() const noexcept;
+
+            /** operate state machien for this syntax on incoming symbol-token @p tk
+             *  with overall parser state in @p p_psm
+             **/
+            void on_symbol_token(const Token & tk,
+                                 ParserStateMachine * p_psm);
+
+            ///@}
+
+        private:
+            static std::unique_ptr<expect_type_xs> make();
+        };
+    } /*namespace scm*/
+} /*namespace xo*/
+
+
+/* end expect_type_xs.hpp */

xo-reader2/include/xo/reader2/syntaxstatetype.hpp

@@ -24,6 +24,9 @@ namespace xo {
             /** expecting a s symbol. See @ref DExpectSymbolSsm **/
             expect_symbol,
 
+            /** expecting a type. See @ref DExpectTypeSsm **/
+            expect_type,
+
             /** handle define-expression. See @ref DDefineSsm **/
             defexpr,