- stackPop will return NULL if stack is empty (used to assert non-emptiness)

- added stackTop (same caveats)

diff --git a/include/Stack.h b/include/Stack.h
index 30abb4bc9ee4594181b255d61dd19700d14989bc..23752e64ef042db594208c24162b0cf0625cbaee 100644 (file)
--- a/include/Stack.h
+++ b/include/Stack.h
@@ -1,5 +1,5 @@
 /*
- * $Id: Stack.h,v 1.6 1998/03/20 18:07:35 rousskov Exp $
+ * $Id: Stack.h,v 1.7 1998/06/04 20:17:56 rousskov Exp $
  *
  * AUTHOR: Alex Rousskov
  *
@@ -41,5 +41,6 @@ typedef Array Stack;
 extern void *stackPop(Stack *s);
 #define stackPush arrayAppend
 #define stackPrePush arrayPreAppend
+extern void *stackTop(Stack *s);
 
 #endif /* ndef _STACK_H_ */

diff --git a/lib/Stack.c b/lib/Stack.c
index 5deed6acebd404e4b3b671fb5c15d13eb9e7832e..36d5dd67cf32e716c09327f9b9082db05261aaf5 100644 (file)
--- a/lib/Stack.c
+++ b/lib/Stack.c
@@ -1,5 +1,5 @@
 /*
- * $Id: Stack.c,v 1.5 1998/03/20 18:07:36 rousskov Exp $
+ * $Id: Stack.c,v 1.6 1998/06/04 20:17:55 rousskov Exp $
  *
  * AUTHOR: Alex Rousskov
  *
@@ -47,6 +47,12 @@ void *
 stackPop(Stack * s)
 {
     assert(s);
-    assert(s->count);
-    return s->items[--s->count];
+    return s->count ? s->items[--s->count] : NULL;
+}
+
+void *
+stackTop(Stack *s)
+{
+    assert(s);
+    return s->count ? s->items[s->count-1] : NULL;
 }