From ff3bceac6288c8df88c8536d4537656c7f34df9b Mon Sep 17 00:00:00 2001
From: Sameer Rahmani <lxsameer@gnu.org>
Date: Sat, 1 Aug 2020 20:14:51 +0100
Subject: [PATCH] Change id attribute of AExpr to virtual method

---
 include/serene/expr.hpp              |  2 +-
 include/serene/list.hpp              |  6 +++---
 include/serene/special_forms/def.hpp |  6 +++---
 include/serene/symbol.hpp            |  6 +++---
 src/list.cpp                         |  7 +++----
 src/special_forms/def.cpp            | 10 +++++-----
 6 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/include/serene/expr.hpp b/include/serene/expr.hpp
index 33525a8..4387ee6 100644
--- a/include/serene/expr.hpp
+++ b/include/serene/expr.hpp
@@ -43,7 +43,7 @@ enum ExprId : unsigned char { aexpr = 0, symbol, list, def };
 
 class AExpr {
 public:
-  ExprId id{0};
+  virtual ExprId id() const = 0;
   virtual std::string string_repr() = 0;
   virtual llvm::Value *codegen(Compiler &compiler, State &state) = 0;
   virtual ~AExpr(){};
diff --git a/include/serene/list.hpp b/include/serene/list.hpp
index 0d8b9a7..f2feb4b 100644
--- a/include/serene/list.hpp
+++ b/include/serene/list.hpp
@@ -45,7 +45,7 @@ public:
   ListNode *head;
   ListNode *tail;
   std::size_t len;
-  ExprId id{list};
+  ExprId id() const override { return list; };
 
   List() : head{nullptr}, tail{nullptr}, len{0} {};
   List(const List &list);
@@ -54,7 +54,7 @@ public:
   List &operator=(const List &other);
   List &operator=(List &&other);
 
-  std::string string_repr();
+  std::string string_repr() override;
   std::size_t length();
 
   void cons(ast_node f);
@@ -64,7 +64,7 @@ public:
 
   void cleanup();
 
-  llvm::Value *codegen(Compiler &compiler, State &state);
+  llvm::Value *codegen(Compiler &compiler, State &state) override;
 
   virtual ~List();
 };
diff --git a/include/serene/special_forms/def.hpp b/include/serene/special_forms/def.hpp
index 6d47366..952934c 100644
--- a/include/serene/special_forms/def.hpp
+++ b/include/serene/special_forms/def.hpp
@@ -48,11 +48,11 @@ private:
   AExpr *value;
 
 public:
-  ExprId id{def};
+  ExprId id() const override { return def; };
 
   Def(AExpr *s, AExpr *v) : sym(s), value(v){};
-  std::string string_repr();
-  llvm::Value *codegen(Compiler &compiler, State &state);
+  std::string string_repr() override;
+  llvm::Value *codegen(Compiler &compiler, State &state) override;
   ~Def();
 };
 
diff --git a/include/serene/symbol.hpp b/include/serene/symbol.hpp
index 0d50281..4341877 100644
--- a/include/serene/symbol.hpp
+++ b/include/serene/symbol.hpp
@@ -36,11 +36,11 @@ class Symbol : public AExpr {
 
 public:
   std::string name;
-  ExprId id{symbol};
+  ExprId id() const override { return symbol; };
 
   Symbol(const std::string &name) : name(name){};
-  std::string string_repr();
-  llvm::Value *codegen(Compiler &compiler, State &state);
+  std::string string_repr() override;
+  llvm::Value *codegen(Compiler &compiler, State &state) override;
 
   ~Symbol();
 };
diff --git a/src/list.cpp b/src/list.cpp
index 064166c..e184cf6 100644
--- a/src/list.cpp
+++ b/src/list.cpp
@@ -187,11 +187,10 @@ Value *List::codegen(Compiler &compiler, State &state) {
   }
 
   auto first_expr{head->data.get()};
-  auto sym{dynamic_cast<Symbol *>(first_expr)};
 
-  if (sym) {
-    if (sym->name == "def") {
-      auto def{make_unique<special_forms::Def>(sym, at(2))};
+  if (first_expr->id() == symbol) {
+    if (first_expr->name == "def") {
+      auto def{make_unique<special_forms::Def>(first_expr, at(2))};
       return def->codegen(compiler, state);
     }
   } else {
diff --git a/src/special_forms/def.cpp b/src/special_forms/def.cpp
index 247519f..f352fe7 100644
--- a/src/special_forms/def.cpp
+++ b/src/special_forms/def.cpp
@@ -47,13 +47,13 @@ Value *Def::codegen(Compiler &compiler, State &state) {
 
   auto symobj{dynamic_cast<Symbol *>(this->sym)};
 
-  if (symobj) {
-    state.set_in_current_ns_root_scope(symobj->name,
-                                       value->codegen(compiler, state));
-    return symobj->codegen(compiler, state);
+  if (symobj->id() != symbol) {
+    return compiler.log_error("First argument of 'def' should be a symbol.");
   }
 
-  return compiler.log_error("First argument of 'def' should be a symbol.");
+  state.set_in_current_ns_root_scope(symobj->name,
+                                     value->codegen(compiler, state));
+  return symobj->codegen(compiler, state);
 };
 
 Def::~Def() { EXPR_LOG("Destroying def"); };