add ATOM_CLOSURE and related functions/macros

2 files changed, 40 insertions, 1 deletions

diff --git a/atom.c b/atom.c
index 9e33255..43626d8 100644
--- a/atom.c
+++ b/atom.c
@@ -1,4 +1,5 @@
 #include "atom.h"
+#include "env.h"
 
 #include <stdlib.h>
 #include <stdio.h>
@@ -59,6 +60,16 @@ struct atom *atom_new_list_empty()
     return atom_new_list(list);
 }
 
+struct atom *atom_new_closure(struct atom *params, struct atom *body,
+    struct env *env)
+{
+    struct atom *atom = atom_new(ATOM_CLOSURE);
+    atom->closure.params = params;
+    atom->closure.body = body;
+    atom->closure.env = env;
+    return atom;
+}
+
 struct atom *atom_clone(struct atom *atom)
 {
     switch (atom->type)
@@ -98,6 +109,15 @@ struct atom *atom_clone(struct atom *atom)
 
         return atom_new_list(list_clone);
     }
+
+    case ATOM_CLOSURE:
+        // TODO: should we clone the env or what? If it is just plainly
+        // cloned, it leads to a infinite loop when we have a closure
+        // bound to a name in the env.
+        return atom_new_closure(atom_clone(atom->closure.params),
+            atom_clone(atom->closure.body),
+            atom->closure.env);
+        break;
     }
 
     return NULL;
@@ -134,7 +154,12 @@ void print_atom(struct atom *atom, int level)
                 printf(" ");
         }
         printf(")");
+        break;
     }
+
+    case ATOM_CLOSURE:
+        printf("<closure@%p>", atom);
+        break;
     }
 
     if (level == 0)
diff --git a/atom.h b/atom.h
index f620af4..7240670 100644
--- a/atom.h
+++ b/atom.h
@@ -16,6 +16,8 @@
 
 #define IS_NIL(ATOM) (ATOM_TYPE(ATOM) == ATOM_NIL)
 
+#define IS_CLOSURE(ATOM) (ATOM_TYPE(ATOM) == ATOM_CLOSURE)
+
 #define CAR(LIST) (LIST_FIRST(LIST))
 #define CDR(LIST) ((LIST) != NULL ? LIST_NEXT((LIST), entries) : NULL)
 #define CDDR(LIST) CDR(CDR(LIST))
@@ -28,10 +30,19 @@ enum
     ATOM_SYMBOL,
     ATOM_LIST,
     ATOM_TRUE,
-    ATOM_FALSE
+    ATOM_FALSE,
+    ATOM_CLOSURE
 };
 
 struct atom;
+struct env;
+
+struct closure
+{
+    struct env *env;
+    struct atom *params;
+    struct atom *body;
+};
 
 LIST_HEAD(list, atom);
 
@@ -48,6 +59,7 @@ struct atom
             int len;
         } str;
         struct list *list;
+        struct closure closure;
     };
 
     LIST_ENTRY(atom) entries;
@@ -59,6 +71,8 @@ struct atom *atom_new_str(const char *str, int len);
 struct atom *atom_new_sym(const char *sym, int len);
 struct atom *atom_new_list(struct list *list);
 struct atom *atom_new_list_empty();
+struct atom *atom_new_closure(struct atom *params, struct atom *body,
+    struct env *env);
 struct atom *atom_clone();
 
 void print_atom(struct atom *atom, int level);