xo-reader2 stack: + #q token + QuoteSsm [WIP - not functional]

include/xo/reader2/DQuoteSsm.hpp

@@ -0,0 +1,166 @@
+/** @file DQuoteSsm.hpp
+ *
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#pragma once
+
+#include "DSyntaxStateMachine.hpp"
+#include "syntaxstatetype.hpp"
+#include <xo/facet/obj.hpp>
+#include <string_view>
+
+namespace xo {
+    namespace scm {
+
+        /**
+         * @pre
+         *
+         *   #q{ quote-expr }
+         *  ^  ^ ^         ^ ^
+         *  |  | |         | (done)
+         *  |  | |         |
+         *  |  | |         quote_3:expect_rightbrace
+         *  |  | quote_2:expect_parsed_expression
+         *  |  quote_1:expect_leftbrace
+         *  quote_0
+         *
+         *   quote_0 --on_quote_token()--> quote_1
+         *   quote_1 --on_leftbrace_token()--> quote_2
+         *   quote_2 --on_parsed_expression()--> quote_3 [will be constant expression]
+         *   quote_3 --on_rightparen_token()--> (done)
+         *
+         * @endpre
+         **/
+
+        class QuoteXst {
+        public:
+            enum class code {
+                invalid = -1,
+
+                quote_0,
+                quote_1,
+                quote_2,
+                quote_3,
+
+                N,
+            };
+
+            explicit QuoteXst(code x) : code_{x} {}
+
+            /** @return string representation for enum @p x **/
+            static const char * _descr(code x);
+
+            code code() const noexcept { return code_; }
+
+            enum code code_;
+        };
+
+        inline std::ostream &
+        operator<<(std::ostream & os, QuoteXst x) {
+            os << QuoteXst::_descr(x.code_);
+            return os;
+        }
+
+        class DQuoteSsm : public DSyntaxStateMachine<DQuoteSsm> {
+        public:
+            using Super = DSyntaxStateMachine<DQuoteSsm>;
+            using TypeDescr = xo::reflect::TypeDescr;
+            using AAllocator = xo::mm::AAllocator;
+            using DArena = xo::mm::DArena;
+            using ppindentinfo = xo::print::ppindentinfo;
+
+        public:
+            /** @defgroup scm-parenssm-ctors **/
+            ///@{
+
+            DQuoteSsm();
+
+            /** create instance using memory from @p parser_mm
+             **/
+            static DQuoteSsm * _make(DArena & parser_mm);
+
+            /** create fop pointing with new DQuoteSsm using memory from @p parser_mm **/
+            static obj<ASyntaxStateMachine,DQuoteSsm> make(DArena & parser_mm);
+
+            /** push DQuoteSsm instance onto @p p_psm stack **/
+            static void start(ParserStateMachine * p_psm);
+
+            ///@}
+            /** @defgroup scm-parenssm-access-methods **/
+            ///@{
+
+            /** identify this nested state machine **/
+            static const char * ssm_classname() { return "DQuoteSsm"; }
+
+            /** internal state **/
+            QuoteXst quotestate() const noexcept { return quote_xst_; }
+
+            ///@}
+            /** @defgroup scm-parenssm-admin-methods admin methods **/
+            ///@{
+
+            /** update ssm state for incoming leftparen token @p tk,
+             *  with overall parser state in @p p_psm
+             **/
+            void on_leftbrace_token(const Token & tk,
+                                    ParserStateMachine * p_psm);
+
+            /** update ssm state for incoming rightparen token @p tk
+             *  with overall parser state in @p p_psm
+             **/
+            void on_rightbrace_token(const Token & tk,
+                                     ParserStateMachine * p_psm);
+
+            ///@}
+            /** @defgroup scm-parenssm-ssm-facet syntaxstatemachine facet methods **/
+            ///@{
+
+            /** identifies this ssm **/
+            syntaxstatetype ssm_type() const noexcept;
+
+            /** text describing expected/allowed input to this ssm in current state. **/
+            std::string_view get_expect_str() const noexcept;
+
+            /** update ssm for token @p tk, with overall state in @p p_psm **/
+            void on_token(const Token & tk,
+                          ParserStateMachine * p_psm);
+
+            /** update ssm for expression @p expr (emitted by nested ssm),
+             *  with overall parser state in @p p_psm
+             **/
+            void on_parsed_expression(obj<AExpression> expr,
+                                      ParserStateMachine * p_psm);
+
+            /** update ssm for expression @p expr (emitted by nested ssm)
+             *  that's immediately followed by token @p tk
+             *  with overall parser state in @p p_psm
+             **/
+            void on_parsed_expression_with_token(obj<AExpression> expr,
+                                                 const Token & tk,
+                                                 ParserStateMachine * p_psmn);
+
+            ///@}
+            /** @defgroup scm-parenssm-printable-facet printable facet methods **/
+            ///@{
+
+            bool pretty(const ppindentinfo & ppii) const;
+
+            ///@}
+
+        private:
+            /** @defgroup scm-parenssm-member-vars **/
+            ///@{
+
+            /** identify quote-expression state **/
+            QuoteXst quote_xst_;
+            /** scaffold expression (representing parenthesized value) here **/
+            obj<AExpression> expr_;
+
+            ///@}
+        };
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end DQuoteSsm.hpp */