xo-expression: initial commit (constant + primitive)

include/xo/expression/Apply.hpp

@@ -0,0 +1,32 @@
+/** @file Apply.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "Expression.hpp"
+
+//#include <cstdint>
+
+namespace xo {
+    namespace ast {
+        /** @class Apply
+         *  @brief syntax for a function call.
+         *
+         *  In general we don't know function to be invoked
+         *  until runtime,  depending on the nature of Expression.
+         *
+         *  For first cut,  we'll just handle the case of a Constant
+         *  that refers to a known function
+         **/
+        class Apply : public Expression {
+            ref::rp<Expression> fn_;
+            std::vector<ref::rp<Expression>> args_;
+        };
+    } /*namespace ast*/
+
+} /*namespace xo*/
+
+
+/** end Apply.hpp **/

include/xo/expression/Constant.hpp

@@ -0,0 +1,78 @@
+/** @file Constant.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "ConstantInterface.hpp"
+#include <type_traits>
+
+namespace xo {
+    namespace ast {
+        /** @class Constant
+         *  @brief syntax for a literal constant.
+         *
+         *  Require:
+         *  1. T must be a POD type (plain old data)
+         *     We need this to be true so that we can generate
+         *     code for constructing a T instance by memcopying
+         *     @ref value_
+         *
+         *  @tp T type of captured literal.
+         **/
+        template <typename T>
+        class Constant : public ConstantInterface {
+        public:
+            using Reflect = xo::reflect::Reflect;
+            using TaggedPtr = xo::reflect::TaggedPtr;
+            using TypeDescr = xo::reflect::TypeDescr;
+
+        public:
+            explicit Constant(const T & x)
+                : ConstantInterface(exprtype::constant),
+                  value_td_{Reflect::require<T>()},
+                  value_(x)
+                {
+                    static_assert(std::is_standard_layout_v<T> && std::is_trivial_v<T>);
+                }
+
+            const T & value() const { return value_; }
+
+            // ----- 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 << "<Constant"
+                   << xtag("type", value_td_->short_name())
+                   << xtag("value", value_)
+                   << ">";
+            }
+
+        private:
+            /** type description for T **/
+            TypeDescr value_td_;
+            /** value of this constant **/
+            T value_;
+        }; /*Constant*/
+
+        template <typename T>
+        ref::rp<Constant<std::remove_reference_t<T>>>
+        make_constant(const T & x) {
+            return new Constant(x);
+        }
+
+    } /*namespace ast*/
+} /*namespace xo*/
+
+/** end Constant.hpp **/

include/xo/expression/ConstantInterface.hpp

@@ -0,0 +1,41 @@
+/** @file ConstantInterface.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "Expression.hpp"
+#include "xo/reflect/Reflect.hpp"
+#include "xo/reflect/TypeDescr.hpp"
+#include <type_traits>
+
+namespace xo {
+    namespace ast {
+        /** @class ConstantInterface
+         *  @brief syntax for a literal constant.
+         **/
+        class ConstantInterface : public Expression {
+        public:
+            using TaggedPtr = xo::reflect::TaggedPtr;
+            using TypeDescr = xo::reflect::TypeDescr;
+
+        public:
+            /** @p extype sets expression-type;  could be constant|primitive **/
+            ConstantInterface(exprtype extype) : Expression{extype} {}
+
+            /** downcast from Expression **/
+            static ref::brw<ConstantInterface> from(ref::brw<Expression> x) {
+                return ref::brw<ConstantInterface>::from(x);
+            }
+
+            /** type description for representation of literal value **/
+            virtual TypeDescr value_td() const = 0;
+            /** reflection-tagged pointer to literal value of this constant **/
+            virtual TaggedPtr value_tp() const = 0;
+        }; /*ConstantInterface*/
+
+    } /*namespace ast*/
+} /*namespace xo*/
+
+/** end ConstantInterface.hpp **/

include/xo/expression/Expression.hpp

@@ -0,0 +1,48 @@
+/** @file Expression.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "xo/refcnt/Refcounted.hpp"
+#include "exprtype.hpp"
+
+namespace xo {
+    namespace ast {
+        /** @class Expression
+         *  @brief abstract syntax tree for an EGAD program
+         *
+         *  (Expression Graph with Automagic Derivation)
+         *
+         *  Things you can do with an Expression:
+         *  - evaluate it using an interpreter
+         *  - execute it on a VM
+         *  - compile using LLVM
+         *    see xo-jit/
+         **/
+        class Expression : public ref::Refcount {
+        public:
+            explicit Expression(exprtype extype) : extype_{extype} {}
+
+            exprtype extype() const { return extype_; }
+
+            /** write human-readable representation to stream **/
+            virtual void display(std::ostream & os) const = 0;
+            /** human-readable string representation **/
+            virtual std::string display_string() const;
+
+        private:
+            /** expression type (constant | apply | ..) for this expression **/
+            exprtype extype_ = exprtype::invalid;
+        }; /*Expression*/
+
+        inline std::ostream &
+        operator<<(std::ostream & os, const Expression & x) {
+            x.display(os);
+            return os;
+        }
+    } /*namespace ast*/
+} /*namespace xo*/
+
+/** end Expression.hpp **/

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 **/

include/xo/expression/PrimitiveInterface.hpp

@@ -0,0 +1,35 @@
+/** @file PrimitiveInterface.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "ConstantInterface.hpp"
+
+//#include <cstdint>
+
+#include <type_traits>
+namespace xo {
+    namespace ast {
+        class PrimitiveInterface : public ConstantInterface {
+        public:
+            PrimitiveInterface() : ConstantInterface(exprtype::primitive) {}
+
+            /** downcast from Expression **/
+            static ref::brw<PrimitiveInterface> from(ref::brw<Expression> x) {
+                return ref::brw<PrimitiveInterface>::from(x);
+            }
+
+            virtual const std::string & name() const = 0;
+
+            //virtual TypeDescr value_td() const override = 0;
+            //virtual TaggedPtr value_tp() const override = 0;
+
+        private:
+        }; /*PrimitiveInterface*/
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/** end PrimitiveInterface.hpp **/

include/xo/expression/exprtype.hpp

@@ -0,0 +1,51 @@
+/** @file exprtype.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include <cstdint>
+
+namespace xo {
+    namespace ast {
+        /** @enum exprtype
+         *  @brief enum to identify subclasses of xo::ast::Expression.
+         *
+         **/
+        enum class exprtype {
+            /** sentinel value **/
+            invalid = -1,
+
+            /** literal constant.  must satisfy both standard_layout_type + trivial **/
+            constant,
+            /** a literal constant that refers to a linkable named function **/
+            primitive,
+            /** function call **/
+            apply,
+
+            /** not an expression.  comes last, counts entries **/
+            n_expr
+        };
+
+        inline const char *
+        expr2str(exprtype x)
+        {
+            switch(x) {
+            case exprtype::invalid: return "?exprtype";
+            case exprtype::constant: return "constant";
+            case exprtype::primitive: return "primitive";
+            case exprtype::apply: return "apply";
+            default: break;
+            }
+
+            return "???exprtype???";
+        }
+
+        /** @brief number of built-in expression types,  repr convenient for array sizing **/
+        static constexpr std::size_t n_exprtype = static_cast<std::size_t>(exprtype::n_expr);
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/** end exprtype.hpp **/