From 9d2b0f17f84975e51235d87514ad8c2d33e2724d Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Thu, 13 Jun 2024 17:59:51 -0400
Subject: [PATCH] xo-expression: + Variable + apply/lambda fixes

---
 include/xo/expression/Apply.hpp    |  2 +-
 include/xo/expression/Lambda.hpp   | 27 +++++++++++++++++--
 include/xo/expression/Variable.hpp | 42 ++++++++++++++++++++++++++++++
 include/xo/expression/exprtype.hpp |  3 +++
 src/expression/CMakeLists.txt      |  1 +
 src/expression/Lambda.cpp          |  1 +
 src/expression/Variable.cpp        | 17 ++++++++++++
 7 files changed, 90 insertions(+), 3 deletions(-)
 create mode 100644 include/xo/expression/Variable.hpp
 create mode 100644 src/expression/Variable.cpp

diff --git a/include/xo/expression/Apply.hpp b/include/xo/expression/Apply.hpp
index 56f6b886..1f2b9a8f 100644
--- a/include/xo/expression/Apply.hpp
+++ b/include/xo/expression/Apply.hpp
@@ -44,7 +44,7 @@ namespace xo {
 
         inline ref::rp<Apply>
         make_apply(const ref::rp<Expression> & fn,
-                              const ref::rp<Expression> & arg1) {
+                   const ref::rp<Expression> & arg1) {
             std::vector<ref::rp<Expression>> argv;
             argv.push_back(arg1);
 
diff --git a/include/xo/expression/Lambda.hpp b/include/xo/expression/Lambda.hpp
index 581ba274..7f6434f8 100644
--- a/include/xo/expression/Lambda.hpp
+++ b/include/xo/expression/Lambda.hpp
@@ -21,10 +21,17 @@ namespace xo {
             /** @p argv   Formal parameters, in left-to-right order
              *  @p body   Expression for body of this function
              **/
-            Lambda(const std::vector<std::string> & argv,
+            Lambda(const std::string & name,
+                   const std::vector<std::string> & argv,
                    const ref::rp<Expression> & body)
-                : Expression(exprtype::lambda), argv_{argv}, body_{body} {}
+                : Expression(exprtype::lambda), name_{name}, argv_{argv}, body_{body} {}
 
+            /** downcast from Expression **/
+            static ref::brw<Lambda> from(ref::brw<Expression> x) {
+                return ref::brw<Lambda>::from(x);
+            }
+
+            const std::string & name() const { return name_; }
             const std::vector<std::string> & argv() const { return argv_; }
             const ref::rp<Expression> & body() const { return body_; }
 
@@ -33,11 +40,27 @@ namespace xo {
             virtual void display(std::ostream & os) const override;
 
         private:
+            /** lambda name.  Initially supporting only form like
+             *    (define (foo x y z)
+             *      (+ (* x x) (* y y) (* z z)))
+             *
+             *  In any case need to supply names for distinct things-for-which-code-is-generated
+             *  so that they can be linked etc.
+             **/
+            std::string name_;
             /** formal argument names **/
             std::vector<std::string> argv_;
             /** function body **/
             ref::rp<Expression> body_;
         }; /*Lambda*/
+
+        inline ref::rp<Lambda>
+        make_lambda(const std::string & name,
+                    const std::vector<std::string> & argv,
+                    const ref::rp<Expression> & body)
+        {
+            return new Lambda(name, argv, body);
+        }
     } /*namespace ast*/
 } /*namespace xo*/
 
diff --git a/include/xo/expression/Variable.hpp b/include/xo/expression/Variable.hpp
new file mode 100644
index 00000000..fc565236
--- /dev/null
+++ b/include/xo/expression/Variable.hpp
@@ -0,0 +1,42 @@
+/** @file Variable.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "Expression.hpp"
+
+namespace xo {
+    namespace ast {
+
+        /** @class Variable
+         *  @brief syntax for a variable reference
+         **/
+        class Variable : public Expression {
+        public:
+            Variable(const std::string & name) : Expression(exprtype::variable), name_{name} {}
+
+            /** downcast from Expression **/
+            static ref::brw<Variable> from(ref::brw<Expression> x) {
+                return ref::brw<Variable>::from(x);
+            }
+
+            const std::string & name() const { return name_; }
+
+            virtual void display(std::ostream & os) const;
+
+        private:
+            /** variable name **/
+            std::string name_;
+        }; /*Variable*/
+
+        inline ref::rp<Variable>
+        make_var(const std::string & name) {
+            return new Variable(name);
+        }
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/** end Variable.hpp **/
diff --git a/include/xo/expression/exprtype.hpp b/include/xo/expression/exprtype.hpp
index 7afa8ff3..91bcfbb5 100644
--- a/include/xo/expression/exprtype.hpp
+++ b/include/xo/expression/exprtype.hpp
@@ -26,6 +26,8 @@ namespace xo {
             apply,
             /** function definition **/
             lambda,
+            /** variable reference **/
+            variable,
 
             /** not an expression.  comes last, counts entries **/
             n_expr
@@ -40,6 +42,7 @@ namespace xo {
             case exprtype::primitive: return "primitive";
             case exprtype::apply: return "apply";
             case exprtype::lambda: return "lambda";
+            case exprtype::variable: return "variable";
             default: break;
             }
 
diff --git a/src/expression/CMakeLists.txt b/src/expression/CMakeLists.txt
index 5db806b2..0ef351e1 100644
--- a/src/expression/CMakeLists.txt
+++ b/src/expression/CMakeLists.txt
@@ -5,6 +5,7 @@ set(SELF_SRCS
     Expression.cpp
     Apply.cpp
     Lambda.cpp
+    Variable.cpp
     #init_reflect.cpp
 )
 
diff --git a/src/expression/Lambda.cpp b/src/expression/Lambda.cpp
index d228bb2c..87f70759 100644
--- a/src/expression/Lambda.cpp
+++ b/src/expression/Lambda.cpp
@@ -8,6 +8,7 @@ namespace xo {
         void
         Lambda::display(std::ostream & os) const {
             os << "<Lambda"
+               << xtag("name", name_)
                << xtag("argv", argv_)
                << xtag("body", body_)
                << ">";
diff --git a/src/expression/Variable.cpp b/src/expression/Variable.cpp
new file mode 100644
index 00000000..c8ab19fc
--- /dev/null
+++ b/src/expression/Variable.cpp
@@ -0,0 +1,17 @@
+/* @file Variable.cpp */
+
+#include "Variable.hpp"
+
+namespace xo {
+    namespace ast {
+        void
+        Variable::display(std::ostream & os) const {
+            os << "<Variable"
+               << xtag("name", name_)
+               << ">";
+        } /*display*/
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/* end Variable.cpp */