数据结构与算法之Stack（栈）——in dart

用dart 语言实现一个简单的stack（栈）。栈的内部用List实现。

 class Stack<E> {
   final List<E> _stack;
   final int capacity;
   int _top;

   Stack(this.capacity)
       : _top = -1,
         _stack = List<E>(capacity);

   bool get isEmpty => _top == -1;
   bool get isFull => _top == capacity - 1;
   int get size => _top + 1;

   void push(E e) {
     if (isFull) throw StackOverFlowException;
     _stack[++_top] = e;
   }

   E pop() {
     if (isEmpty) throw StackEmptyException;
     return _stack[_top--];
   }

   E get top {
     if (isEmpty) throw StackEmptyException;
     return _stack[_top];
   }
 }

 class StackOverFlowException implements Exception {
   const StackOverFlowException();
   String toString() => 'StackOverFlowException';
 }

 class StackEmptyException implements Exception {
   const StackEmptyException();
   String toString() => 'StackEmptyException';
 }

 void main() {
   var stack = Stack<int>(10);
   for (var i = 0; i < stack.capacity; i++) stack.push(i * i);
   print(stack.top);

   var sbuff = StringBuffer();
   while (!stack.isEmpty) sbuff.write('${stack.pop()} ');
   print(sbuff.toString());
 }