/**
 * 字符栈
 * @author sunt
 */
public class CharStack {
    /**
     * 本栈对应的stringBuffer
     */
    private StringBuffer stack = null;
    
    /**
     * 栈的容量
     */
    private int size = 0;

    /**
     * 构造函数
     */
    public CharStack(){
        //缺省栈的容量为256
        this.stack =new StringBuffer(256);
        this.size=256;
    }
    /**
     * 构造函数
     * @param size
     */
    public CharStack(int size){
        if (size <= 0) {
            throw new RuntimeException("The size must over zero!");
        }
        this.stack = new StringBuffer(size);
        this.size=size;
    }
    
    /**
     * 入栈
     */
    public void push(char c){
        if (!isFull()) {
            stack.append(c);
        } else {
            throw new RuntimeException("The stack is full!");
        }
    }
    /**
     * 出栈
     */
    public char pop(){
        if (!isEmpty()) {
            char c = stack.charAt(stack.length() - 1);
            stack = stack.delete(stack.length() - 1,
                    stack.length());
            return c;
        } else {
            throw new RuntimeException("The stack is empty!");
        }
    }
    /**
     * 获得栈的所有字符成员
     * @return
     */
    public char[] list(){
        char[] cha = new char[stack.length()];
        for(int i = 0;i<stack.length();i++){
            cha[i]= stack.charAt(i);
        }
        return cha;
    }
    /**
     * 转化为字符串
     */
    public String toString(){
        return stack.toString();
    }

    /**
     * 判断栈是否为空
     */
    private boolean isEmpty() {
        return this.stack.length() == 0 ? true : false;
    }

    /**
     * 判断栈是否已满
     */
    private boolean isFull() {
        return this.stack.length() == this.size ? true : false;
    }
}