From a28dfd8695812122c1dc6648535bd35e4166af64 Mon Sep 17 00:00:00 2001
From: Jason Turner <jason@emptycrate.com>
Date: Sat, 24 Sep 2011 14:21:21 -0600
Subject: [PATCH] Get & variable declarations working

---
 .../chaiscript/language/chaiscript_common.hpp |  2 +-
 .../chaiscript/language/chaiscript_eval.hpp   | 46 ++++++++++++++-----
 .../chaiscript/language/chaiscript_parser.hpp |  5 +-
 unittests/var_ref_decl.chai                   | 19 ++++++++
 4 files changed, 59 insertions(+), 13 deletions(-)
 create mode 100644 unittests/var_ref_decl.chai

diff --git a/include/chaiscript/language/chaiscript_common.hpp b/include/chaiscript/language/chaiscript_common.hpp
index 74fb410..f8af5e1 100644
--- a/include/chaiscript/language/chaiscript_common.hpp
+++ b/include/chaiscript/language/chaiscript_common.hpp
@@ -112,7 +112,7 @@ namespace chaiscript
   struct AST_Node : std::enable_shared_from_this<AST_Node> {
     public:
       const std::string text;
-      const int identifier;
+      const int identifier; //< \todo shouldn't this be a strongly typed enum value?
       std::shared_ptr<const std::string> filename;
       File_Position start, end;
       std::vector<AST_NodePtr> children;
diff --git a/include/chaiscript/language/chaiscript_eval.hpp b/include/chaiscript/language/chaiscript_eval.hpp
index e4d4d5a..aaad2c8 100644
--- a/include/chaiscript/language/chaiscript_eval.hpp
+++ b/include/chaiscript/language/chaiscript_eval.hpp
@@ -295,7 +295,16 @@ namespace chaiscript
             } else if (this->children[1]->text == "=") {
               try {
                 if (lhs.is_undef()) {
-                  retval = t_ss.call_function("clone", retval);
+                  if (!this->children.empty() && 
+                      !this->children[0]->children.empty() 
+                      && this->children[0]->children[0]->identifier == AST_Node_Type::Reference)
+                  {
+                    /// \todo This does not handle the case of an unassigned reference variable
+                    ///       being assigned outside of its declaration
+                    lhs.assign(retval);
+                  } else {
+                    retval = t_ss.call_function("clone", retval);
+                  }
                   retval.clear_dependencies();
                 }
 
@@ -335,13 +344,21 @@ namespace chaiscript
           AST_Node(t_ast_node_text, t_id, t_fname, t_start_line, t_start_col, t_end_line, t_end_col) { }
         virtual ~Var_Decl_AST_Node() {}
         virtual Boxed_Value eval_internal(chaiscript::detail::Dispatch_Engine &t_ss){
-          try {
-            t_ss.add_object(this->children[0]->text, Boxed_Value());
+          if (this->children[0]->identifier == AST_Node_Type::Reference)
+          {
+            return this->children[0]->eval(t_ss);
+          } else {
+            std::string idname = this->children[0]->text;
+
+            try {
+              t_ss.add_object(idname, Boxed_Value());
+            }
+            catch (const exception::reserved_word_error &) {
+              throw exception::eval_error("Reserved word used as variable '" + idname + "'");
+            }
+            return t_ss.get_object(idname);
           }
-          catch (const exception::reserved_word_error &) {
-            throw exception::eval_error("Reserved word used as variable '" + this->children[0]->text + "'");
-          }
-          return t_ss.get_object(this->children[0]->text);
+
         }
 
     };
@@ -848,16 +865,23 @@ namespace chaiscript
         }
     };
 
-    struct Reference_Node : public AST_Node {
+    struct Reference_AST_Node : public AST_Node {
       public:
-        Reference_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Prefix, const std::shared_ptr<std::string> &t_fname=std::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :
+        Reference_AST_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Reference, const std::shared_ptr<std::string> &t_fname=std::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :
           AST_Node(t_ast_node_text, t_id, t_fname, t_start_line, t_start_col, t_end_line, t_end_col)
         { }
 
-        virtual ~Reference_Node() {}
         virtual Boxed_Value eval_internal(chaiscript::detail::Dispatch_Engine &t_ss){
-          return Boxed_Value();
+          try {
+            t_ss.add_object(this->children[0]->text, Boxed_Value());
+          }
+          catch (const exception::reserved_word_error &) {
+            throw exception::eval_error("Reserved word used as variable '" + this->children[0]->text + "'");
+          }
+          return t_ss.get_object(this->children[0]->text);
         }
+
+        virtual ~Reference_AST_Node() {}
     };
 
     struct Prefix_AST_Node : public AST_Node {
diff --git a/include/chaiscript/language/chaiscript_parser.hpp b/include/chaiscript/language/chaiscript_parser.hpp
index 797bb35..eb4eda6 100644
--- a/include/chaiscript/language/chaiscript_parser.hpp
+++ b/include/chaiscript/language/chaiscript_parser.hpp
@@ -1634,8 +1634,11 @@ namespace chaiscript
               throw exception::eval_error("Incomplete '&' expression", File_Position(m_line, m_col), *m_filename);
             }
 
-            build_match(AST_NodePtr(new eval::Reference_Node()), prev_stack_top);
+            build_match(AST_NodePtr(
+                  new eval::Reference_AST_Node()), prev_stack_top);
           }
+
+          return retval;
         }
 
         /**
diff --git a/unittests/var_ref_decl.chai b/unittests/var_ref_decl.chai
new file mode 100644
index 0000000..58bfa24
--- /dev/null
+++ b/unittests/var_ref_decl.chai
@@ -0,0 +1,19 @@
+auto l = 5
+auto & k = l;
+
+
+assert_equal(l, k)
+
+l = 10
+
+assert_equal(10, l)
+assert_equal(k, l)
+
+auto & j
+j = l // assignment outside of declaration does *not* result in reference assignment
+j = 15
+
+assert_equal(15, j)
+assert_equal(k, l)
+assert_equal(10, l)
+