package runtime;

import java.util.Stack;

public class EvaluationStack {

	public EvaluationStack() {
		stack_ = new Stack<RuntimeObject>();
	}
	
	private Stack<RuntimeObject> stack_;
	
	public void push(RuntimeObject obj) {
		stack_.push(obj);
		
	}

}

@@ -117,30 +117,38 @@
 w Stack%3C
-RuntimeObject%3E
+StackFrame%3E();%0A%09%09enter
 ();%0A%09%7D%0A%09
@@ -167,30 +167,213 @@
 ack%3C
-RuntimeObject%3E stack_;
+StackFrame%3E stack_;%0A%09private StackFrame current_;%0A%09%0A%09public void enter() %7B%0A%09%09current_ = new StackFrame();%0A%09%09stack_.push(current_);%0A%09%7D%0A%09%0A%09public void leave() %7B%0A%09%09stack_.pop();%0A%09%09current_ = stack_.peek();%0A%09%7D
 %0A%09%0A%09
@@ -412,21 +412,23 @@
 bj) %7B%0A%09%09
-stack
+current
 _.push(o
@@ -433,16 +433,73 @@
 (obj);%0A%09
-%09
+%7D%0A%09%0A%09public RuntimeObject pop() %7B%0A%09%09return current_.pop();
 %0A%09%7D%0A%0A%7D%0A

Complete `EvaluationStack` class.