6 files changed, 63 insertions, 20 deletions

diff --git a/builtin.cpp b/builtin.cpp
index cec007e..7c5f3c7 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -1258,12 +1258,24 @@ BUILTIN_PROC_DEF(is_eqv) {
 
 BUILTIN_PROC_DEF(is_equal) {
 
-#define INC1(x) (++(x) == t1 ? (x) = q1:0)
-#define INC2(x) (++(x) == t2 ? (x) = q2:0)
+//#define INC1(x) (++(x) == t1 ? (x) = q1:0)
+//#define INC2(x) (++(x) == t2 ? (x) = q2:0)
+#define INC1(x) (++(x))
+#define INC2(x) (++(x))
+#define CHK1 \
+do { \
+    if (r1 == q1 + EQUAL_QUEUE_SIZE)  \
+        throw NormalError(RUN_ERR_QUEUE_OVERFLOW); \
+} while (0)
+
+#define CHK2 \
+do { \
+    if (r2 == q2 + EQUAL_QUEUE_SIZE)  \
+        throw NormalError(RUN_ERR_QUEUE_OVERFLOW); \
+} while (0)
+
     
     static EvalObj *q1[EQUAL_QUEUE_SIZE], *q2[EQUAL_QUEUE_SIZE];
-    static EvalObj ** const t1 = q1 + EQUAL_QUEUE_SIZE;
-    static EvalObj ** const t2 = q2 + EQUAL_QUEUE_SIZE;
 
     ARGS_EXACTLY_TWO;
     EvalObj **l1 = q1, **r1 = l1;
@@ -1285,13 +1297,17 @@ BUILTIN_PROC_DEF(is_equal) {
         {
             *r1 = TO_PAIR(a)->car;
             INC1(r1);
+            CHK1;
             *r1 = TO_PAIR(a)->cdr;
             INC1(r1);
+            CHK1;
 
             *r2 = TO_PAIR(b)->car;
             INC2(r2);
+            CHK2;
             *r2 = TO_PAIR(b)->cdr;
             INC2(r2);
+            CHK2;
         }
         else if (otype & CLS_VECT_OBJ)
         {
@@ -1305,6 +1321,7 @@ BUILTIN_PROC_DEF(is_equal) {
             {
                 *r1 = TO_PAIR(a)->car;
                 INC1(r1);
+                CHK1;
             }
 
             for (EvalObjVec::iterator 
@@ -1313,6 +1330,7 @@ BUILTIN_PROC_DEF(is_equal) {
             {
                 *r2 = TO_PAIR(b)->car;
                 INC2(r2);
+                CHK2;
             }
         }
         else if (otype & CLS_BOOL_OBJ)
diff --git a/consts.cpp b/consts.cpp
index ffa0b30..d0c767c 100644
--- a/consts.cpp
+++ b/consts.cpp
@@ -15,5 +15,7 @@ const char *ERR_MSG[] = {
     "Unknown character name: %s",
     "Improper pair structure",
     "Improper vector structure",
-    "Bad formal %s in expression"
+    "Bad formal %s in expression",
+    "Queue overflowed: the expected expansion is too long!",
+    "%s stack overflowed!"
 };
diff --git a/consts.h b/consts.h
index f9e2425..4a7c900 100644
--- a/consts.h
+++ b/consts.h
@@ -16,7 +16,9 @@ enum ErrCode {
     RUN_ERR_UNKNOWN_CHAR_NAME,
     PAR_ERR_IMPROPER_PAIR,
     PAR_ERR_IMPROPER_VECT,
-    SYN_ERR_BAD_FORMAL
+    SYN_ERR_BAD_FORMAL,
+    RUN_ERR_QUEUE_OVERFLOW,
+    RUN_ERR_STACK_OVERFLOW
 };
 
 extern const char *ERR_MSG[];
diff --git a/eval.cpp b/eval.cpp
index 2d03c0c..aa4f729 100644
--- a/eval.cpp
+++ b/eval.cpp
@@ -93,6 +93,8 @@ EvalObj *Evaluator::run_expr(Pair *prog) {
 
     while((*eval_stack)->is_ret_addr())
     {
+        if (top_ptr == eval_stack + EVAL_STACK_SIZE)
+            throw TokenError("Evaluation", RUN_ERR_STACK_OVERFLOW);
         for (; pc && pc->skip; pc = pc->next);
         if (pc)
             push(pc, top_ptr, envt);
diff --git a/model.cpp b/model.cpp
index 8599bd0..6c5e4a0 100644
--- a/model.cpp
+++ b/model.cpp
@@ -71,24 +71,29 @@ string EvalObj::ext_repr() {
     {
         if ((*(top_ptr - 1))->done)
         {
-            hash.erase((*--top_ptr)->ori);
-            obj = (*(top_ptr - 1))->next((*top_ptr)->repr);
+            top_ptr -= 2;
+            obj = (*top_ptr)->next((*(top_ptr + 1))->repr);
             if (obj)
             {
-                *top_ptr++ = obj->get_repr_cons();
-                if (hash.count((*(top_ptr - 1))->ori))
-                    *(top_ptr - 1) = new ReprStr("#cyc#");
+                *(++top_ptr) = obj->get_repr_cons();
+                if (hash.count((*top_ptr)->ori))
+                    *top_ptr = new ReprStr("#inf#");
             }
             else
-                *(top_ptr - 1) = new ReprStr((*(top_ptr - 1))->repr);
+            {
+                hash.erase((*top_ptr)->ori);
+                *top_ptr = new ReprStr((*top_ptr)->repr);
+            }
         }
         else
         {
-            obj = (*(top_ptr - 1))->next("");
-            *top_ptr++ = obj->get_repr_cons();
-            if (hash.count((*(top_ptr - 1))->ori))
-                *(top_ptr - 1) = new ReprStr("#cyc#");
+            top_ptr--;
+            obj = (*top_ptr)->next("");
+            *(++top_ptr) = obj->get_repr_cons();
+            if (hash.count((*top_ptr)->ori))
+                *top_ptr = new ReprStr("#inf#");
         }
+        top_ptr++;
     }
     string &res = (*repr_stack)->repr;
     if (this->is_pair_obj())
@@ -315,11 +320,11 @@ EvalObj *PairReprCons::next(const string &prev) {
         if (TO_PAIR(ptr)->car->is_pair_obj()) 
             repr += ")";
         ptr = TO_PAIR(ptr)->cdr;
+        if (ptr == empty_list)
+            return NULL;
         repr += " ";
         if (ptr->is_simple_obj())
             repr += ". ";
-        if (ptr == empty_list)
-            return NULL;
         return ptr;
     }
     else 
@@ -333,10 +338,21 @@ VectReprCons::VectReprCons(VecObj *_ptr, EvalObj *_ori) :
 
 EvalObj *VectReprCons::next(const string &prev) {
     repr += prev;
+
+    if (idx && ptr->get_obj(idx - 1)->is_pair_obj())
+        repr += ")";
+
     if (idx == ptr->get_size())
     {
-        *repr.rbegin() = ')';
+        repr += ")";
         return NULL;
     }
-    else return ptr->get_obj(idx++);
+    else 
+    {
+        if (idx) repr += " ";
+        EvalObj *res = ptr->get_obj(idx++);
+        if (res->is_pair_obj())
+            repr += "(";
+        return res;
+    }
 }
diff --git a/parser.cpp b/parser.cpp
index ff21b7b..97482d4 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -149,6 +149,9 @@ Pair *ASTGenerator::absorb(Tokenizor *tk) {
     FrameObj **top_ptr = parse_stack;
     for (;;)
     {
+        if (top_ptr == parse_stack + PARSE_STACK_SIZE)
+            throw TokenError("Parser", RUN_ERR_STACK_OVERFLOW);
+
         if (top_ptr - parse_stack > 1 && 
                 !IS_BRAKET(*(top_ptr - 1)) &&
                 IS_BRAKET(*(top_ptr - 2)))