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The-Nook-GamesTM/Proficiencies/stack.h

@@ -0,0 +1,40 @@
+#ifndef STACK_H
+#define STACK_H
+
+#include <stdlib.h>
+
+union element_type
+{
+    int operand;
+    char operator;
+};
+
+enum element_tag {
+    TOKEN_OPERAND,
+    TOKEN_OPERATOR
+};
+
+struct expression_element {
+    enum element_tag tag;
+    union element_type data;
+};
+
+struct stack {
+    struct expression_element data;
+    struct stack *next;
+};
+
+/* Push a new element to the stack and returns the new top */
+struct stack *stack_push(struct stack *s, struct expression_element element);
+
+/* Pop from the stack and returns its new top */
+struct stack *stack_pop(struct stack *s);
+
+/* Empty and frees the whole stack */
+void stack_destroy(struct stack **s);
+
+/* Returns the current top of the stack */
+struct expression_element stack_peek(struct stack *s);
+
+
+#endif /* ! STACK_H */