From c54fefd17fb54029bbb62c363197c808b0fecc6b Mon Sep 17 00:00:00 2001
From: Teddy <ted.sybil@gmail.com>
Date: Mon, 5 Aug 2013 09:41:19 +0800
Subject: added list support

---
 builtin.cpp |  4 ++++
 builtin.h   |  1 +
 eval.cpp    |  1 +
 model.cpp   | 11 ++++++++++-
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/builtin.cpp b/builtin.cpp
index f1b518f..17c5e94 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -296,6 +296,10 @@ EvalObj *builtin_cdr(ArgList *args) {
     return TO_CONS(args->car)->cdr;
 }
 
+EvalObj *builtin_list(ArgList *args) {
+    return args;
+}
+
 EvalObj *builtin_plus(ArgList *args) {
     // TODO: type conversion and proper arithmetic
     int res = 0;
diff --git a/builtin.h b/builtin.h
index 8d2a6a0..997c0c6 100644
--- a/builtin.h
+++ b/builtin.h
@@ -136,5 +136,6 @@ EvalObj *builtin_display(ArgList *);
 EvalObj *builtin_cons(ArgList *);
 EvalObj *builtin_car(ArgList *);
 EvalObj *builtin_cdr(ArgList *);
+EvalObj *builtin_list(ArgList *);
 
 #endif
diff --git a/eval.cpp b/eval.cpp
index de06209..56bd06c 100644
--- a/eval.cpp
+++ b/eval.cpp
@@ -24,6 +24,7 @@ void Evaluator::add_builtin_routines() {
     ADD_ENTRY("cons", new BuiltinProcObj(builtin_cons, "cons"));
     ADD_ENTRY("car", new BuiltinProcObj(builtin_car, "car"));
     ADD_ENTRY("cdr", new BuiltinProcObj(builtin_cdr, "cdr"));
+    ADD_ENTRY("list", new BuiltinProcObj(builtin_list, "list"));
     ADD_ENTRY("if", new SpecialOptIf());
     ADD_ENTRY("lambda", new SpecialOptLambda());
     ADD_ENTRY("define", new SpecialOptDefine());
diff --git a/model.cpp b/model.cpp
index fab17d6..83d5b79 100644
--- a/model.cpp
+++ b/model.cpp
@@ -55,7 +55,16 @@ Cons::Cons(EvalObj *_car, EvalObj *_cdr) :
     next(NULL) {}
 
 string Cons::ext_repr() { 
-    return "(" + car->ext_repr() + " . " + cdr->ext_repr() + ")"; 
+    string res = "(";
+    EvalObj *ptr = this;
+    for (;ptr != empty_list && ptr->is_cons_obj();
+            ptr = TO_CONS(ptr)->cdr)
+        res += TO_CONS(ptr)->car->ext_repr() + " ";
+    if (ptr == empty_list)
+        res[res.length() - 1] = ')';
+    else
+        res += ". " + ptr->ext_repr() + ")";
+    return res;
 }
 
 #ifdef DEBUG
-- 
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