python堆栈类

# -*- coding:utf-8 -*-
# file: pystack.py
#
class PyStack:                                                                  # 堆栈类
        def __init__(self, size = 20):
                self.stack = []                                                 # 堆栈列表
                self.size = size                                                # 堆栈大小
                self.top = -1                                                   # 栈顶位置
        def setSize(self, size):                                                # 设置堆栈大小
                self.size = size
        def push(self, element):                                                # 元素进栈
                if self.isFull():
                        raise 'PyStackOverflow'                                 # 如果栈满则引发异常
                else:
                        self.stack.append(element)
                        self.top = self.top + 1
        def pop(self):                                                          # 元素出栈
                if self.isEmpty():
                        raise 'PyStackUnderflow'                                # 如果栈为空则引发异常
                else:
                        element = self.stack[-1]
                        self.top = self.top - 1
                        del self.stack[-1]
                        return element
        def Top(self):                                                          # 获取栈顶位置
                return self.top
        def empty(self):                                                        # 清空栈
                self.stack = []
                self.top = -1
        def isEmpty(self):                                                      # 是否为空栈
                if self.top == -1:
                        return True
                else:
                        return False
        def isFull(self):                                                       # 是否为满栈
                if self.top == self.size - 1:
                        return True
                else:
                        return False
if __name__ == '__main__':
        stack = PyStack()                                                       # 创建栈
        for i in range(10):
                stack.push(i)                                                   # 元素进栈
        print stack.Top()                                                       # 输出栈顶位置
        for i in range(10):
                print stack.pop()                                               # 元素出栈
        stack.empty()                                                           # 清空栈
        for i in range(21):
                stack.push(i)                                                   # 此处将引发异常