xo-expression: + binding_path + assoc w/ each Variable

src/expression/CMakeLists.txt

@@ -7,6 +7,7 @@ set(SELF_SRCS
     Lambda.cpp
     Variable.cpp
     IfExpr.cpp
+    LocalEnv.cpp
 )
 
 xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 ${SELF_SRCS})

src/expression/LocalEnv.cpp

@@ -0,0 +1,31 @@
+/* file LocalEnv.cpp
+ *
+ * author: Roland Conybeare
+ */
+
+#include "LocalEnv.hpp"
+
+namespace xo {
+    namespace ast {
+        binding_path
+        LocalEnv::lookup_binding(const std::string & vname) const
+        {
+            int j_slot = 0;
+            for (const auto & arg : argv_) {
+                if (arg->name() == vname)
+                    return { 0 /*i_link*/, j_slot };
+                ++j_slot;
+            }
+
+            auto tmp = parent_env_->lookup_binding(vname);
+
+            if (tmp.i_link_ == -1)
+                return tmp;
+            else
+                return { tmp.i_link_ + 1, tmp.j_slot_ };
+        } /*lookup_binding*/
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/* end LocalEnv.cpp */

src/expression/Variable.cpp

@@ -1,9 +1,16 @@
 /* @file Variable.cpp */
 
 #include "Variable.hpp"
+#include "Environment.hpp"
 
 namespace xo {
     namespace ast {
+        void
+        Variable::attach_envs(ref::brw<Environment> e) {
+            /** e makes accessible all enclosing lexical scopes **/
+            this->path_ = e->lookup_binding(this->name_);
+        } /*attach_envs*/
+
         void
         Variable::display(std::ostream & os) const {
             os << "<Variable"