xo-expression: initial commit (constant + primitive)

include/xo/expression/Primitive.hpp

@@ -0,0 +1,89 @@
+/** @file Primitive.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "PrimitiveInterface.hpp"
+//#include <cstdint>
+
+namespace xo {
+    namespace ast {
+        /** @class Primitive
+         *  @brief syntax for a constant that refers to a known function.
+         *
+         *  Two cases here:
+         *  1. primitive refers to a function that is supported directly in llvm
+         *     (e.g. floating-point addition)
+         *  2. primitive refers to a compiled (C/C++) function that we can invoke at runtime
+         *
+         *  In any case, a primitive serves as both declaration and definition
+         *  (May be possible to relax this to declaration-only using null value_ as sentinel..?)
+         **/
+        template <typename FunctionPointer>
+        class Primitive: public PrimitiveInterface {
+        public:
+            using Reflect = xo::reflect::Reflect;
+            using TaggedPtr = xo::reflect::TaggedPtr;
+            using TypeDescr = xo::reflect::TypeDescr;
+
+        public:
+            Primitive(const std::string & name,
+                      FunctionPointer fnptr)
+                : PrimitiveInterface(),
+                  name_{name},
+                  value_td_{Reflect::require<FunctionPointer>()},
+                  value_{fnptr}
+                {}
+
+            FunctionPointer value() const { return value_; }
+
+            // ----- PrimitiveInterface -----
+
+            virtual std::string const & name() const { return name_; }
+
+            // ----- ConstantInterface -----
+
+            virtual TypeDescr value_td() const override { return value_td_; }
+            virtual TaggedPtr value_tp() const override {
+                /* note: idk why,  but need to spell this out in two steps with gcc 13.2 */
+                const void * erased_cptr = &value_;
+                void * erased_ptr = const_cast<void*>(erased_cptr);
+
+                return TaggedPtr(value_td_, erased_ptr);
+            }
+
+            // ----- Expression -----
+
+            virtual void display(std::ostream & os) const override {
+                os << "<Primitive"
+                   << xtag("name", name_)
+                   << xtag("type", this->value_td()->short_name())
+                   << xtag("value", this->value())
+                   << ">";
+            }
+
+        private:
+            // from Expression:
+            //   exprtype extype_
+
+            /** name of this primitive, e.g. '+', 'sqrt' **/
+            std::string name_;
+            /** type description for FunctionPointer **/
+            TypeDescr value_td_;
+            /** address of executable function **/
+            FunctionPointer value_;
+        }; /*Primitive*/
+
+        /** adopt function @p x as a callable primitive function named @p name **/
+        template <typename FunctionPointer>
+        ref::rp<Primitive<FunctionPointer>>
+        make_primitive(const std::string & name, FunctionPointer x) {
+            return new Primitive(name, x);
+        }
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/** end Primitive.hpp **/