xo-reader2: handle parsed typedescr + use in DDefineSsm

idl/SyntaxStateMachine.json5

@@ -5,6 +5,7 @@
         "\"ParserStateMachine.hpp\"",
         "\"syntaxstatetype.hpp\"",
         "<xo/tokenizer2/Token.hpp>",
+        "<xo/reflect/TypeDescr.hpp>",
     ],
     // extra includes in SyntaxStateMachine.hpp, if any
     user_hpp_includes: [],
@@ -20,6 +21,7 @@
         "Assistant to schematika parser dedicated to particular syntax"
     ],
     types: [
+        { name: "TypeDescr", doc: [ "reflected c++ type" ], definition: "xo::reflect::TypeDescr" },
         // { name: string, doc: [ string ], definition: string },
     ],
     const_methods: [
@@ -88,5 +90,14 @@
                 {type: "ParserStateMachine *", name: "p_psm"},
             ],
         },
+        {
+            name: "on_parsed_typedescr",
+            doc: ["operate state machine for incoming type description @p td"],
+            return_type: "void",
+            args: [
+                {type: "TypeDescr", name: "td"},
+                {type: "ParserStateMachine *", name: "p_psm"},
+            ],
+        },
     ],
 }

include/xo/reader2/DDefineSsm.hpp

@@ -71,6 +71,7 @@ namespace xo {
          **/
         class DDefineSsm {
         public:
+            using TypeDescr = xo::reflect::TypeDescr;
             using AAllocator = xo::mm::AAllocator;
             using DArena = xo::mm::DArena;
             using ppindentinfo = xo::print::ppindentinfo;
@@ -139,6 +140,12 @@ namespace xo {
             void on_parsed_symbol(std::string_view sym,
                                   ParserStateMachine * p_psm);
 
+            /** update state for this syntax after parsing a type-description @p td,
+             *  overall parser state in @p p_psm
+             **/
+            void on_parsed_typedescr(TypeDescr td,
+                                     ParserStateMachine * p_psm);
+
             ///@}
             /** @defgroup scm-define-printable-facet printable facet methods **/
             ///@{

include/xo/reader2/DExpectSymbolSsm.hpp

@@ -22,6 +22,7 @@ namespace xo {
         class DExpectSymbolSsm {
         public:
             using DArena = xo::mm::DArena;
+            using TypeDescr = xo::reflect::TypeDescr;
             using ppindentinfo = xo::print::ppindentinfo;
 
         public:
@@ -57,8 +58,29 @@ namespace xo {
              **/
             std::string_view get_expect_str() const noexcept;
 
+            /** update state for this syntax after parsing a symbol @p sym;
+             *  overall parser state in @p p_psm.
+             *
+             *  NOTE:
+             *  might not be obvious that this is unreachable.
+             *  DExpectSymbolSsm converts a symbol token,
+             *  and delivers it to parent ssm using this entry point.
+             *  This method would only be called if consecutive
+             *  DExpectSymbolSsm instances on parser stack;
+             *  which scenario never occurs in Schematika syntax
+             **/
+            void on_parsed_symbol(std::string_view sym,
+                                  ParserStateMachine * p_psm);
+
+            /** update state for this syntax after parsing a type-description @p td
+             *  in nested state machine.
+             *  (provided to satisfy ASyntaxStateMachine api. not reachable)
+             **/
+            void on_parsed_typedescr(TypeDescr td,
+                                     ParserStateMachine * p_psm);
+
             /** update state for this syntax on incoming token @p tk,
-             *  overall parser state in @p p_psm
+             *  overall parser state in @p p_psm.
              **/
             void on_def_token(const Token & tk,
                               ParserStateMachine * p_psm);
@@ -75,21 +97,6 @@ namespace xo {
             void on_colon_token(const Token & tk,
                                 ParserStateMachine * p_psm);
 
-            /** update state for this syntax after parsing a symbol @p sym;
-             *  overall parser state in @p p_psm.
-             *
-             *  NOTE:
-             *  might not be obvious that this is unreachable.
-             *  DExpectSymbolSsm converts a symbol token,
-             *  and delivers it to parent ssm using this entry point.
-             *  This method would only be called if consecutive
-             *  DExpectSymbolSsm instances on parser stack;
-             *  which scenario never occurs in Schematika syntax
-             **/
-            void on_parsed_symbol(std::string_view sym,
-                                  ParserStateMachine * p_psm);
-
-
             ///@}
             /** @defgroup scm-expectsymbol-printable-facet printable facet methods **/
             ///@{

include/xo/reader2/DExpectTypeSsm.hpp

@@ -23,6 +23,7 @@ namespace xo {
          **/
         class DExpectTypeSsm {
         public:
+            using TypeDescr = xo::reflect::TypeDescr;
             using DArena = xo::mm::DArena;
             using ppindentinfo = xo::print::ppindentinfo;
 
@@ -70,7 +71,7 @@ namespace xo {
             void on_colon_token(const Token & tk,
                                 ParserStateMachine * p_psm);
 
-            /** Never called.
+            /** (Never called).
              *  Operate state machine for this syntax after symbol
              *  emitted from nested ssm.
              *  Impossible path for DExpectTypeSsm until such time as it relies
@@ -80,6 +81,14 @@ namespace xo {
             void on_parsed_symbol(std::string_view sym,
                                   ParserStateMachine * p_psm);
 
+            /** operate state machine for this syntax on receiving type-description
+             *  from nested parser.
+             *  Currently (jan 2026) impossible path for DExpectTypeSsm.
+             *  Active path is via on_symbol_token()
+             **/
+            void on_parsed_typedescr(TypeDescr td,
+                                     ParserStateMachine * p_psm);
+
             ///@}
             /** @defgroup scm-expecttype-printable-facet printable facet methods **/
             ///@{

include/xo/reader2/DExprSeqState.hpp

@@ -39,6 +39,7 @@ namespace xo {
          **/
         class DExprSeqState {
         public:
+            using TypeDescr = xo::reflect::TypeDescr;
             using AAllocator = xo::mm::AAllocator;
             using ppindentinfo = xo::print::ppindentinfo;
 
@@ -90,6 +91,12 @@ namespace xo {
              **/
             void on_parsed_symbol(std::string_view sym, ParserStateMachine * p_psm);
 
+            /** update state for this syntax on parsed type-description @p td
+             *  from nested ssm.
+             *  overall parser state in @p p_psm
+             **/
+            void on_parsed_typedescr(TypeDescr td, ParserStateMachine * p_psm);
+
             ///@}
             /** @defgroup scm-exprseq-printable-facet printable facet methods **/
             ///@{

include/xo/reader2/ParserStateMachine.hpp

@@ -29,6 +29,7 @@ namespace xo {
          **/
         class ParserStateMachine {
         public:
+            using TypeDescr = xo::reflect::TypeDescr;
             using AAllocator = xo::mm::AAllocator;
             using ArenaConfig = xo::mm::ArenaConfig;
             using DArena = xo::mm::DArena;
@@ -88,9 +89,16 @@ namespace xo {
             /** @defgroup scm-parserstatemachine-inputmethods input methods **/
             ///@{
 
-            /** update state to respond to prsed symbol @p sym **/
+            /** update state to respond to parsed symbol @p sym
+             *  (from nested parsing state)
+             **/
             void on_parsed_symbol(std::string_view sym);
 
+            /** update state to respond to parsed type-description @p td
+             *  (from nested parsing state)
+             **/
+            void on_parsed_typedescr(TypeDescr td);
+
             /** update state to respond to input token @p tk.
              *  record output (if any) in @ref result_
              **/
@@ -109,7 +117,6 @@ namespace xo {
             void on_colon_token(const Token & tk);
 
             ///@}
-
             /** @defgroup scm-parserstatemachine-error-entrypoints error entry points **/
             ///@{
 
@@ -136,6 +143,15 @@ namespace xo {
             void illegal_input_on_symbol(std::string_view ssm_name,
                                          std::string_view sym,
                                          std::string_view expect_str);
+
+            /** report illegal input arriving in syntax state machine (ssm) @p ssm_name
+             *  receiving assembled type-description @p td.
+             *  @p expect_str sketches expected input in current ssm state
+             **/
+            void illegal_input_on_typedescr(std::string_view ssm_name,
+                                            TypeDescr td,
+                                            std::string_view expect_str);
+
             ///@}
 
         private:

include/xo/reader2/ssm/ASyntaxStateMachine.hpp

@@ -17,6 +17,7 @@
 #include "ParserStateMachine.hpp"
 #include "syntaxstatetype.hpp"
 #include <xo/tokenizer2/Token.hpp>
+#include <xo/reflect/TypeDescr.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/facet/facet_implementation.hpp>
 #include <xo/facet/typeseq.hpp>
@@ -41,6 +42,8 @@ public:
     using typeseq = xo::facet::typeseq;
     using Copaque = const void *;
     using Opaque = void *;
+    /** reflected c++ type **/
+    using TypeDescr = xo::reflect::TypeDescr;
     ///@}
 
     /** @defgroup scm-syntaxstatemachine-methods **/
@@ -64,6 +67,8 @@ public:
     virtual void on_colon_token(Opaque data, const Token & tk, ParserStateMachine * p_psm)  = 0;
     /** update  stat machine for incoming parsed symbol @p sym **/
     virtual void on_parsed_symbol(Opaque data, std::string_view sym, ParserStateMachine * p_psm)  = 0;
+    /** operate state machine for incoming type description @p td **/
+    virtual void on_parsed_typedescr(Opaque data, TypeDescr td, ParserStateMachine * p_psm)  = 0;
     ///@}
 }; /*ASyntaxStateMachine*/
 

include/xo/reader2/ssm/IPrintable_DExpectTypeSsm.hpp

@@ -2,7 +2,7 @@
  *
  *  Generated automagically from ingredients:
  *  1. code generator:
- *       [/Users/roland/proj/xo-umbrella2/xo-facet/codegen/genfacet]
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
  *     arguments:
  *       --input [idl/IPrintable_DExpectTypeSsm.json5]
  *  2. jinja2 template for abstract facet .hpp file:

include/xo/reader2/ssm/ISyntaxStateMachine_Any.hpp

@@ -44,6 +44,7 @@ namespace scm {
 
         /** integer identifying a type **/
         using typeseq = xo::facet::typeseq;
+        using TypeDescr = ASyntaxStateMachine::TypeDescr;
 
         ///@}
         /** @defgroup scm-syntaxstatemachine-any-methods **/
@@ -64,6 +65,7 @@ namespace scm {
         [[noreturn]] void on_if_token(Opaque, const Token &, ParserStateMachine *)  override;
         [[noreturn]] void on_colon_token(Opaque, const Token &, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_symbol(Opaque, std::string_view, ParserStateMachine *)  override;
+        [[noreturn]] void on_parsed_typedescr(Opaque, TypeDescr, ParserStateMachine *)  override;
 
         ///@}
 

include/xo/reader2/ssm/ISyntaxStateMachine_DDefineSsm.hpp

@@ -41,6 +41,7 @@ namespace xo {
         public:
             /** @defgroup scm-syntaxstatemachine-ddefinessm-type-traits **/
             ///@{
+            using TypeDescr = xo::scm::ASyntaxStateMachine::TypeDescr;
             using Copaque = xo::scm::ASyntaxStateMachine::Copaque;
             using Opaque = xo::scm::ASyntaxStateMachine::Opaque;
             ///@}
@@ -63,6 +64,8 @@ namespace xo {
             static void on_colon_token(DDefineSsm & self, const Token & tk, ParserStateMachine * p_psm);
             /** update  stat machine for incoming parsed symbol @p sym **/
             static void on_parsed_symbol(DDefineSsm & self, std::string_view sym, ParserStateMachine * p_psm);
+            /** operate state machine for incoming type description @p td **/
+            static void on_parsed_typedescr(DDefineSsm & self, TypeDescr td, ParserStateMachine * p_psm);
             ///@}
         };
 

include/xo/reader2/ssm/ISyntaxStateMachine_DExpectSymbolSsm.hpp

@@ -41,6 +41,7 @@ namespace xo {
         public:
             /** @defgroup scm-syntaxstatemachine-dexpectsymbolssm-type-traits **/
             ///@{
+            using TypeDescr = xo::scm::ASyntaxStateMachine::TypeDescr;
             using Copaque = xo::scm::ASyntaxStateMachine::Copaque;
             using Opaque = xo::scm::ASyntaxStateMachine::Opaque;
             ///@}
@@ -63,6 +64,8 @@ namespace xo {
             static void on_colon_token(DExpectSymbolSsm & self, const Token & tk, ParserStateMachine * p_psm);
             /** update  stat machine for incoming parsed symbol @p sym **/
             static void on_parsed_symbol(DExpectSymbolSsm & self, std::string_view sym, ParserStateMachine * p_psm);
+            /** operate state machine for incoming type description @p td **/
+            static void on_parsed_typedescr(DExpectSymbolSsm & self, TypeDescr td, ParserStateMachine * p_psm);
             ///@}
         };
 

include/xo/reader2/ssm/ISyntaxStateMachine_DExpectTypeSsm.hpp

@@ -2,7 +2,7 @@
  *
  *  Generated automagically from ingredients:
  *  1. code generator:
- *       [/Users/roland/proj/xo-umbrella2/xo-facet/codegen/genfacet]
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
  *     arguments:
  *       --input [idl/ISyntaxStateMachine_DExpectTypeSsm.json5]
  *  2. jinja2 template for abstract facet .hpp file:
@@ -41,6 +41,7 @@ namespace xo {
         public:
             /** @defgroup scm-syntaxstatemachine-dexpecttypessm-type-traits **/
             ///@{
+            using TypeDescr = xo::scm::ASyntaxStateMachine::TypeDescr;
             using Copaque = xo::scm::ASyntaxStateMachine::Copaque;
             using Opaque = xo::scm::ASyntaxStateMachine::Opaque;
             ///@}
@@ -63,6 +64,8 @@ namespace xo {
             static void on_colon_token(DExpectTypeSsm & self, const Token & tk, ParserStateMachine * p_psm);
             /** update  stat machine for incoming parsed symbol @p sym **/
             static void on_parsed_symbol(DExpectTypeSsm & self, std::string_view sym, ParserStateMachine * p_psm);
+            /** operate state machine for incoming type description @p td **/
+            static void on_parsed_typedescr(DExpectTypeSsm & self, TypeDescr td, ParserStateMachine * p_psm);
             ///@}
         };
 

include/xo/reader2/ssm/ISyntaxStateMachine_DExprSeqState.hpp

@@ -41,6 +41,7 @@ namespace xo {
         public:
             /** @defgroup scm-syntaxstatemachine-dexprseqstate-type-traits **/
             ///@{
+            using TypeDescr = xo::scm::ASyntaxStateMachine::TypeDescr;
             using Copaque = xo::scm::ASyntaxStateMachine::Copaque;
             using Opaque = xo::scm::ASyntaxStateMachine::Opaque;
             ///@}
@@ -63,6 +64,8 @@ namespace xo {
             static void on_colon_token(DExprSeqState & self, const Token & tk, ParserStateMachine * p_psm);
             /** update  stat machine for incoming parsed symbol @p sym **/
             static void on_parsed_symbol(DExprSeqState & self, std::string_view sym, ParserStateMachine * p_psm);
+            /** operate state machine for incoming type description @p td **/
+            static void on_parsed_typedescr(DExprSeqState & self, TypeDescr td, ParserStateMachine * p_psm);
             ///@}
         };
 

include/xo/reader2/ssm/ISyntaxStateMachine_Xfer.hpp

@@ -16,6 +16,7 @@
 #include "ParserStateMachine.hpp"
 #include "syntaxstatetype.hpp"
 #include <xo/tokenizer2/Token.hpp>
+#include <xo/reflect/TypeDescr.hpp>
 
 namespace xo {
 namespace scm {
@@ -30,6 +31,7 @@ namespace scm {
         using Impl = ISyntaxStateMachine_DRepr;
         /** integer identifying a type **/
         using typeseq = ASyntaxStateMachine::typeseq;
+        using TypeDescr = ASyntaxStateMachine::TypeDescr;
         ///@}
 
         /** @defgroup scm-syntaxstatemachine-xfer-methods **/
@@ -65,6 +67,9 @@ namespace scm {
         void on_parsed_symbol(Opaque data, std::string_view sym, ParserStateMachine * p_psm)  override {
             return I::on_parsed_symbol(_dcast(data), sym, p_psm);
         }
+        void on_parsed_typedescr(Opaque data, TypeDescr td, ParserStateMachine * p_psm)  override {
+            return I::on_parsed_typedescr(_dcast(data), td, p_psm);
+        }
 
         ///@}
 

include/xo/reader2/ssm/RSyntaxStateMachine.hpp

@@ -31,6 +31,7 @@ public:
     using ObjectType = Object;
     using DataPtr = Object::DataPtr;
     using typeseq = xo::reflect::typeseq;
+    using TypeDescr = ASyntaxStateMachine::TypeDescr;
     ///@}
 
     /** @defgroup scm-syntaxstatemachine-router-ctors **/
@@ -70,6 +71,9 @@ public:
     void on_parsed_symbol(std::string_view sym, ParserStateMachine * p_psm)  {
         return O::iface()->on_parsed_symbol(O::data(), sym, p_psm);
     }
+    void on_parsed_typedescr(TypeDescr td, ParserStateMachine * p_psm)  {
+        return O::iface()->on_parsed_typedescr(O::data(), td, p_psm);
+    }
 
     ///@}
     /** @defgroup scm-syntaxstatemachine-member-vars **/

src/reader2/DDefineSsm.cpp

@@ -420,7 +420,7 @@ namespace xo {
         DDefineSsm::on_parsed_symbol(std::string_view sym_name,
                                      ParserStateMachine * p_psm)
         {
-            if (this->defstate_ == defexprstatetype::def_1) {
+            if (defstate_ == defexprstatetype::def_1) {
                 this->defstate_ = defexprstatetype::def_2;
 
                 const DUniqueString * sym
@@ -460,6 +460,32 @@ namespace xo {
                                            this->get_expect_str());
         }
 
+        void
+        DDefineSsm::on_parsed_typedescr(TypeDescr td,
+                                        ParserStateMachine * p_psm)
+        {
+            scope log(XO_DEBUG(true), xtag("td", td));
+
+            if (defstate_ == defexprstatetype::def_3) {
+                this->defstate_ = defexprstatetype::def_4;
+
+                // note: not present in x0-reader/ version
+                def_expr_.assign_valuetype(td);
+
+#ifdef NOT_YET
+                this->cvt_expr_ = ConvertExpr::make(td, nullptr);
+                def_expr_->assign_rhs(cvt_expr_);
+#endif
+                log && log("STUB: ConvertExpr not implemented, TypeDescr not captured");
+
+                return;
+            }
+
+            p_psm->illegal_input_on_typedescr("DDefineSsm::on_parsed_typedescr",
+                                              td,
+                                              this->get_expect_str());
+        }
+
         void
         DDefineSsm::on_symbol_token(const Token & tk,
                                     ParserStateMachine * p_psm)

src/reader2/DExpectSymbolSsm.cpp

@@ -56,6 +56,24 @@ namespace xo {
             return "symbol";
         }
 
+        void
+        DExpectSymbolSsm::on_parsed_symbol(std::string_view sym,
+                                           ParserStateMachine * p_psm)
+        {
+            p_psm->illegal_input_on_symbol("DExpectSymbolSsm::on_parsed_symbol",
+                                           sym,
+                                           this->get_expect_str());
+        }
+
+        void
+        DExpectSymbolSsm::on_parsed_typedescr(TypeDescr td,
+                                              ParserStateMachine * p_psm)
+        {
+            p_psm->illegal_input_on_typedescr("DExpectSymbolSsm::on_parsed_typedescr",
+                                              td,
+                                              this->get_expect_str());
+        }
+
         void
         DExpectSymbolSsm::on_symbol_token(const Token & tk,
                                           ParserStateMachine * p_psm)
@@ -104,15 +122,6 @@ namespace xo {
                                           this->get_expect_str());
         }
 
-        void
-        DExpectSymbolSsm::on_parsed_symbol(std::string_view sym,
-                                           ParserStateMachine * p_psm)
-        {
-            p_psm->illegal_input_on_symbol("DExpectSymbolSsm::on_parsed_symbol",
-                                           sym,
-                                           this->get_expect_str());
-        }
-
         bool
         DExpectSymbolSsm::pretty(const ppindentinfo & ppii) const
         {

src/reader2/DExpectTypeSsm.cpp

@@ -115,10 +115,7 @@ namespace xo {
             }
 
             p_psm->pop_ssm();
-
+            p_psm->on_parsed_typedescr(td);
-            log && log("STUB: missing on_typedescr() call");
-
-            //p_psm->on_typedescr(td);
         }
 
         void
@@ -130,6 +127,15 @@ namespace xo {
                                            this->get_expect_str());
         }
 
+        void
+        DExpectTypeSsm::on_parsed_typedescr(TypeDescr td,
+                                            ParserStateMachine * p_psm)
+        {
+            p_psm->illegal_input_on_typedescr("ExpectTypeSsm",
+                                              td,
+                                              this->get_expect_str());
+        }
+
         bool
         DExpectTypeSsm::pretty(const ppindentinfo & ppii) const
         {

src/reader2/DExprSeqState.cpp

@@ -178,6 +178,15 @@ namespace xo {
                                            this->get_expect_str());
         }
 
+        void
+        DExprSeqState::on_parsed_typedescr(TypeDescr td,
+                                           ParserStateMachine * p_psm)
+        {
+            p_psm->illegal_input_on_typedescr("DExprSeqState::on_parsed_typedescr",
+                                              td,
+                                              this->get_expect_str());
+        }
+
         bool
         DExprSeqState::pretty(const ppindentinfo & ppii) const
         {

src/reader2/IPrintable_DExpectTypeSsm.cpp

@@ -2,7 +2,7 @@
  *
  *  Generated automagically from ingredients:
  *  1. code generator:
- *       [/Users/roland/proj/xo-umbrella2/xo-facet/codegen/genfacet]
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
  *     arguments:
  *       --input [idl/IPrintable_DExpectTypeSsm.json5]
  *  2. jinja2 template for abstract facet .hpp file:

src/reader2/ISyntaxStateMachine_Any.cpp

@@ -64,6 +64,12 @@ ISyntaxStateMachine_Any::on_parsed_symbol(Opaque, std::string_view, ParserStateM
     _fatal();
 }
 
+auto
+ISyntaxStateMachine_Any::on_parsed_typedescr(Opaque, TypeDescr, ParserStateMachine *)  -> void
+{
+    _fatal();
+}
+
 
 } /*namespace scm*/
 } /*namespace xo*/

src/reader2/ISyntaxStateMachine_DDefineSsm.cpp

@@ -52,6 +52,11 @@ namespace xo {
         {
             self.on_parsed_symbol(sym, p_psm);
         }
+        auto
+        ISyntaxStateMachine_DDefineSsm::on_parsed_typedescr(DDefineSsm & self, TypeDescr td, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_typedescr(td, p_psm);
+        }
 
     } /*namespace scm*/
 } /*namespace xo*/

src/reader2/ISyntaxStateMachine_DExpectSymbolSsm.cpp

@@ -52,6 +52,11 @@ namespace xo {
         {
             self.on_parsed_symbol(sym, p_psm);
         }
+        auto
+        ISyntaxStateMachine_DExpectSymbolSsm::on_parsed_typedescr(DExpectSymbolSsm & self, TypeDescr td, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_typedescr(td, p_psm);
+        }
 
     } /*namespace scm*/
 } /*namespace xo*/

src/reader2/ISyntaxStateMachine_DExpectTypeSsm.cpp

@@ -2,7 +2,7 @@
  *
  *  Generated automagically from ingredients:
  *  1. code generator:
- *       [/Users/roland/proj/xo-umbrella2/xo-facet/codegen/genfacet]
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
  *     arguments:
  *       --input [idl/ISyntaxStateMachine_DExpectTypeSsm.json5]
  *  2. jinja2 template for abstract facet .hpp file:
@@ -52,6 +52,11 @@ namespace xo {
         {
             self.on_parsed_symbol(sym, p_psm);
         }
+        auto
+        ISyntaxStateMachine_DExpectTypeSsm::on_parsed_typedescr(DExpectTypeSsm & self, TypeDescr td, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_typedescr(td, p_psm);
+        }
 
     } /*namespace scm*/
 } /*namespace xo*/

src/reader2/ISyntaxStateMachine_DExprSeqState.cpp

@@ -52,6 +52,11 @@ namespace xo {
         {
             self.on_parsed_symbol(sym, p_psm);
         }
+        auto
+        ISyntaxStateMachine_DExprSeqState::on_parsed_typedescr(DExprSeqState & self, TypeDescr td, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_typedescr(td, p_psm);
+        }
 
     } /*namespace scm*/
 } /*namespace xo*/

src/reader2/ParserStateMachine.cpp

@@ -113,6 +113,16 @@ namespace xo {
             this->stack_->top().on_parsed_symbol(sym, this);
         }
 
+        void
+        ParserStateMachine::on_parsed_typedescr(TypeDescr td)
+        {
+            scope log(XO_DEBUG(debug_flag_), xtag("td", td));
+
+            assert(stack_);
+
+            this->stack_->top().on_parsed_typedescr(td, this);
+        }
+
         void
         ParserStateMachine::on_token(const Token & tk)
         {
@@ -271,6 +281,29 @@ namespace xo {
 
             this->capture_error(ssm_name, errmsg);
         }
+
+        void
+        ParserStateMachine::illegal_input_on_typedescr(std::string_view ssm_name,
+                                                       TypeDescr td,
+                                                       std::string_view expect_str)
+        {
+            // TODO:
+            // - want to write error message using DArena
+            // - need something like log_streambuf and/or tostr() that's arena-aware
+
+            auto errmsg_string = tostr("Unexpected type-description for parsing state",
+                                       xtag("td", td),
+                                       xtag("expecting", expect_str),
+                                       xtag("ssm", ssm_name),
+                                       xtag("via", "ParserStateMachine::illegal_input_on_typedescr"));
+
+            assert(expr_alloc_);
+
+            auto errmsg = DString::from_view(expr_alloc_,
+                                             std::string_view(errmsg_string));
+
+            this->capture_error(ssm_name, errmsg);
+        }
     } /*namespace scm*/
 } /*namespace xo*/