xo-expression: initial commit (constant + primitive)

.gitignore

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+# emacs projectile config
+.projectile
+# clangd working space (see emacs+lsp)
+.cache
+# typical cmake build directory (source-tree-nephew)
+.build*
+# symlink to builddir/compile_commands.json;  should be set manually in dev sandbox
+compile_commands.json

CMakeLists.txt

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+# expression/CMakeLists.txt
+
+cmake_minimum_required(VERSION 3.10)
+
+project(xo_expression VERSION 0.1)
+
+include(GNUInstallDirs)
+include(cmake/xo-bootstrap-macros.cmake)
+
+xo_cxx_toplevel_options3()
+
+# ----------------------------------------------------------------
+# c++ settings
+
+set(PROJECT_CXX_FLAGS "")
+#set(PROJECT_CXX_FLAGS "-fconcepts-diagnostics-depth=2")  # gcc-only!
+add_definitions(${PROJECT_CXX_FLAGS})
+
+# ----------------------------------------------------------------
+
+# must complete definition of expression lib before configuring examples
+add_subdirectory(src/expression)
+
+xo_export_cmake_config(${PROJECT_NAME} ${PROJECT_VERSION} ${PROJECT_NAME}Targets)
+
+# ----------------------------------------------------------------
+
+add_subdirectory(example)
+#add_subdirectory(utest)
+
+# ----------------------------------------------------------------
+# docs targets depend on all the other library/utest targets
+#
+#add_subdirectory(docs)
+
+# end CMakeLists.txt

LICENSE

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+Copyright (c) 2024 Roland Conybeare <git3ub@nym.hush.com>, All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+Please also refer to the file .github/CONTRIBUTING.md, which clarifies licensing of
+external contributions to this project including patches, pull requests, etc.

cmake/xo-bootstrap-macros.cmake

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+# ----------------------------------------------------------------
+# for example:
+#   $ PREFIX=/usr/local   # for example
+#   $ cmake -DCMAKE_MODULE_PATH=prefix -DCMAKE_INSTALL_PREFIX=$PREFIX -B .build
+#
+# will get
+#   CMAKE_MODULE_PATH
+# from xo-cmake-config --cmake-module-path
+#
+# and expect .cmake macros in
+#   CMAKE_MODULE_PATH/xo_macros/xo_cxx.cmake
+# ----------------------------------------------------------------
+
+find_program(XO_CMAKE_CONFIG_EXECUTABLE NAMES xo-cmake-config REQUIRED)
+
+if ("${XO_CMAKE_CONFIG_EXECUTABLE}" STREQUAL "XO_CMAKE_CONFIG_EXECUTABLE-NOT_FOUND")
+    message(FATAL "could not find xo-cmake-config executable")
+endif()
+
+message(STATUS "XO_CMAKE_CONFIG_EXECUTABLE=${XO_CMAKE_CONFIG_EXECUTABLE}")
+
+if (NOT XO_SUBMODULE_BUILD)
+    if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL prefix))
+        # default to typical install location for xo-project-macros
+        execute_process(COMMAND ${XO_CMAKE_CONFIG_EXECUTABLE} --cmake-module-path OUTPUT_VARIABLE CMAKE_MODULE_PATH)
+        message(STATUS "CMAKE_MODULE_PATH=${CMAKE_MODULE_PATH}")
+    endif()
+endif()
+
+# needs to have been installed somewhere on CMAKE_MODULE_PATH,
+# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
+#
+include(xo_macros/xo_cxx)
+
+xo_cxx_bootstrap_message()

cmake/xo_expressionConfig.cmake.in

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+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+find_dependency(reflect)
+include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
+check_required_components("@PROJECT_NAME@")

example/CMakeLists.txt

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+add_subdirectory(ex1)

example/ex1/CMakeLists.txt

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+# xo-expression/example/ex1/CMakeLists.txt
+
+set(SELF_EXE xo_expression_ex1)
+set(SELF_SRCS ex1.cpp)
+
+if (XO_ENABLE_EXAMPLES)
+    xo_add_executable(${SELF_EXE} ${SELF_SRCS})
+    xo_self_dependency(${SELF_EXE} xo_expression)
+    xo_dependency(${SELF_EXE} refcnt)
+endif()
+
+# end CMakeLists.txt

example/ex1/ex1.cpp

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+/** @file ex1.cpp **/
+
+#include "xo/expression/Constant.hpp"
+#include <iostream>
+
+int
+main() {
+    using xo::ast::make_constant;
+
+    auto expr = make_constant(7);
+}
+
+
+/** end ex1.cpp **/

include/xo/expression/Apply.hpp

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+/** @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

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+/** @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

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+/** @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

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+/** @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

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+/** @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

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+/** @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

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+/** @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 **/

src/expression/CMakeLists.txt

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+# expression/CMakeLists.txt
+
+set(SELF_LIB xo_expression)
+set(SELF_SRCS
+    Expression.cpp
+    #init_reflect.cpp
+)
+
+xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 ${SELF_SRCS})
+xo_dependency(${SELF_LIB} reflect)
+#xo_dependency(${SELF_LIB} indentlog)
+#xo_dependency(${SELF_LIB} subsys)
+
+# end CMakeLists.txt

src/expression/Expression.cpp

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+/* @file Expression.cpp */
+
+#include "Expression.hpp"
+
+namespace xo {
+    namespace ast {
+        std::string
+        Expression::display_string() const {
+            return tostr(*this);
+        }
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/* end Expression.cpp */