package com.xdl.data_stru;

/**
 * @author xudaolong 串的結構本質和char[]這種沒什麼區別;
 */
@SuppressWarnings("unused")
public class Day_Four_SeqString {

    private char[] str;
    private int length;

    private void init(int max_num) {
	this.str = new char[max_num + 1];// 定義中的[]是元素的個數
	str[0] = '\0';// 標誌
	this.length = 0;
    }

    // 賦值
    private void assign(char[] ch) {
	this.str = new char[ch.length + 1];
	for (int i = 0; i < ch.length; i++) {
	    this.str[i] = ch[i];
	}
	this.str[ch.length] = '\0';
	this.length = ch.length;
    }

    // 賦值,和上面沒什麼差別;
    private void assign(Day_Four_SeqString s) {
	this.str = new char[s.length + 1];
	for (int i = 0; i < s.length; i++) {
	    this.str[i] = s.str[i];
	}
	this.str[s.length] = '\0';
	this.length = s.length;
    }

    /**
     * @param ch
     *            核心:忍法:替身術,追加在原有的str後;
     */
    private void concat(char[] ch) {
	Day_Four_SeqString str = new Day_Four_SeqString();
	str.assign(this.str);
	// 上面兩句是為了儲存已存在的str.然後重置,char[]在初始化的時候已經被設定固定了;
	this.str = new char[ch.length + this.length + 1];
	for (int i = 0; i < this.length; i++) {
	    this.str[i] = str.str[i];
	}
	for (int i = 0; i < ch.length; i++) {
	    this.str[i + this.length] = ch[i];
	}
	this.length = this.length + ch.length;
	this.str[this.length] = '\0';
    }
    //求子串
    private Day_Four_SeqString substr(int start, int len) {
	Day_Four_SeqString str = new Day_Four_SeqString();
	//以下條件對輸入值 start 和 len 進行控制,觸發一個就byebye了,哦,其實挺隨意的; 
	 if (start <1 || start > this.length || is_null() || len >this.length -start +1) {
	    str.init(0);
	    return str;//空置
	}
	 str.init(this.length);
	 for (int i = 0; i < len; i++) {
	    str.str[i] = this.str[i+(start-1)]; //start 對應的下表是start -1;
	}
	return str;
    }
    //定位
    private int index(char [] ch) {
	int i = 0,j = 0;
	while (i<this.length&& j<ch.length) {
	    if (this.str[i]==ch[j]) {
		i++;
		j++;
	    }else {
		i = i - j +1 ;
		j = 0;
	    }
	}
	if (j == ch.length) {
	    return i-ch.length+1;
	}
	return 0;
    }
    private boolean is_null() {
	if (this.length == 0) {
	    return true;
	}
	return false;
    }

    public int getLen() {
	return length;
    }
}