From b45d7d9592477e846656b7ed2e9ed7afd02896fe Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Tue, 22 Oct 2013 16:02:20 +0900
Subject: [PATCH] add eof-object type

---
 include/picrin/value.h |  2 ++
 src/codegen.c          |  1 +
 src/gc.c               |  2 ++
 src/port.c             | 33 +++++++++++++++++++++++++++++++++
 src/value.c            |  2 ++
 5 files changed, 40 insertions(+)

diff --git a/include/picrin/value.h b/include/picrin/value.h
index 2dcf3673..cfc958cf 100644
--- a/include/picrin/value.h
+++ b/include/picrin/value.h
@@ -7,6 +7,7 @@ enum pic_vtype {
   PIC_VTYPE_FALSE,
   PIC_VTYPE_UNDEF,
   PIC_VTYPE_FLOAT,
+  PIC_VTYPE_EOF,
   PIC_VTYPE_HEAP
 };
 
@@ -23,6 +24,7 @@ enum pic_tt {
   PIC_TT_NIL,
   PIC_TT_BOOL,
   PIC_TT_FLOAT,
+  PIC_TT_EOF,
   PIC_TT_UNDEF,
   /* heap */
   PIC_TT_PAIR,
diff --git a/src/codegen.c b/src/codegen.c
index 1d26dab6..4079fb41 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -383,6 +383,7 @@ pic_gen(pic_state *pic, struct pic_irep *irep, pic_value obj, struct pic_env *en
   }
   case PIC_TT_PROC:
   case PIC_TT_UNDEF:
+  case PIC_TT_EOF:
   case PIC_TT_PORT: {
     pic_error(pic, "invalid expression given");
   }
diff --git a/src/gc.c b/src/gc.c
index b06f6eb6..c834c096 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -159,6 +159,7 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
   case PIC_TT_NIL:
   case PIC_TT_BOOL:
   case PIC_TT_FLOAT:
+  case PIC_TT_EOF:
   case PIC_TT_UNDEF:
     pic_abort(pic, "logic flaw");
   }
@@ -276,6 +277,7 @@ gc_finalize_object(pic_state *pic, struct pic_object *obj)
   case PIC_TT_NIL:
   case PIC_TT_BOOL:
   case PIC_TT_FLOAT:
+  case PIC_TT_EOF:
   case PIC_TT_UNDEF:
     pic_abort(pic, "logic flaw");
   }
diff --git a/src/port.c b/src/port.c
index e41edbf0..be7884c9 100644
--- a/src/port.c
+++ b/src/port.c
@@ -32,6 +32,9 @@ write(pic_state *pic, pic_value obj)
   case PIC_TT_FLOAT:
     printf("%.10g", pic_float(obj));
     break;
+  case PIC_TT_EOF:
+    printf("#<eof-object>");
+    break;
   case PIC_TT_UNDEF:
     printf("#<undef>");
     break;
@@ -103,9 +106,39 @@ pic_port_newline(pic_state *pic)
   return pic_false_value();
 }
 
+static pic_value
+pic_port_eof_object_p(pic_state *pic)
+{
+  pic_value v;
+
+  pic_get_args(pic, "o", &v);
+
+  if (v.type == PIC_VTYPE_EOF) {
+    return pic_true_value();
+  }
+  else {
+    return pic_false_value();
+  }
+}
+
+static pic_value
+pic_port_eof_object(pic_state *pic)
+{
+  pic_value v;
+
+  pic_get_args(pic, "");
+
+  v.type = PIC_VTYPE_EOF;
+  v.u.data = NULL;
+
+  return v;
+}
+
 void
 pic_init_port(pic_state *pic)
 {
   pic_defun(pic, "write", pic_port_write);
   pic_defun(pic, "newline", pic_port_newline);
+  pic_defun(pic, "eof-object?", pic_port_eof_object_p);
+  pic_defun(pic, "eof-object", pic_port_eof_object);
 }
diff --git a/src/value.c b/src/value.c
index 7fa303d2..fff723d4 100644
--- a/src/value.c
+++ b/src/value.c
@@ -17,6 +17,8 @@ pic_type(pic_value v)
     return PIC_TT_UNDEF;
   case PIC_VTYPE_FLOAT:
     return PIC_TT_FLOAT;
+  case PIC_VTYPE_EOF:
+    return PIC_TT_EOF;
   case PIC_VTYPE_HEAP:
     return ((struct pic_object *)v.u.data)->tt;
   }