奋战一晚上，把这学期的C#实验全部搞定了。刚刚提交完实验，从实验室出来时间只有一种隔世为人的感觉………….
几个实验里最难的是一个文档分析的程序，可以进行文档的关键词搜索，并支持通过对Key Word添加逻辑符号进行搜索的方式。做完了这个突然有一种编搜索引擎的冲动 >_< 呵呵…………..
其实现在想起来挺笨的，最多的时间花在了对表达式的解析上，应该使用数据结构中的模式匹配来做比较简单，虽然用到了栈结构，但毕竟是现成的拿来就能用。最后我还是用了比较复杂的递归算法，现在是能满足实验要求了，但在复杂度上还有很多问题。贴在这里留个纪念吧…………….
class
OPTs
{
public
static
ArrayList ReadFile(String input)
{
//读文件并返回字典
ArrayList text = new
ArrayList();
String text_line;
int totalLength = 0;
StreamReader freader = File.OpenText(input);
Console.WriteLine("Reading {0} – please wait !", input);
while ((text_line = freader.ReadLine()) != null)
{
if (text_line.Length == 0)
continue;
text.Add(text_line);
totalLength += text_line.Length;
}
freader.Close();
Console.WriteLine("Reading {0} – OK, done !", input);
Console.WriteLine("\nThe text file {0}\n contains {1} lines in {2} bytes.\n", input, text.Count, totalLength);
Console.WriteLine("entering text into dictionary – please wait !");
return text;
}
public
static
void GetQuery(/String input/)
{
//导入字典
ArrayList dictionary = new
ArrayList();
String input = "F:/alice_emma.txt";
dictionary = ReadFile(input); //读文件
Console.WriteLine("entering text into dictionary – OK, done !");
//取得要求
String TheQuery;
do
{ //循环区的需求式
Console.Write("\nPlease enter a query or ‘q’ to Quit : ");
TheQuery = Console.ReadLine();
TheQuery.ToLower();
if (!TheQuery.Equals("q"))
analyse(TheQuery, dictionary);
}
while (!TheQuery.Equals("q"));
}
public
static
void analyse(String TheQuery, ArrayList dictionary)
{
//分析需求，调整顺序，显示查询结果
String[] queryelement = TheQuery.Split(‘ ‘);
Query result; //结果Query
String[] queryelement_turn = new
String[queryelement.Length];
for (int a = 0; a < queryelement.Length; a++) // 为后面的递归分析做准备，反向需求式
queryelement_turn[queryelement.Length - 1 - a] = queryelement[a];
for (int a = 0; a < queryelement.Length; a++)
{
if (queryelement_turn[a] == "!")
{
queryelement_turn[a] = queryelement_turn[a - 1];
queryelement_turn[a - 1] = "!";
}
if (queryelement_turn[a] == "(")
queryelement_turn[a] = ")";
else
if (queryelement_turn[a] == ")")
queryelement_turn[a] = "(";
}
result = done(queryelement_turn, dictionary, 0);
result.eval(); //Query计算结果
result.display(); //Query显示
Console.WriteLine("");
foreach(Object i in result.Solution) //显示句子
Console.WriteLine("[" + ( (int)i + 1 ) + "]: " + dictionary[ (int)i ] );
}
public
static
Query done(String[] queryelement, ArrayList dictionary, int now) //递归分析需求式
{
Query result = null;
int i = now;
switch (queryelement[i])
{ //依据不同的判断结果构造NEW语句
case
"!":
if (i + 1 == queryelement.Length - 1 || queryelement[i + 2] == ")")
result = new
NotQuery(new
NameQuery(queryelement[i + 1], dictionary), dictionary);
else
if (queryelement[i + 1] == "(")
{
if (searchbracketmatch(queryelement, i) == (queryelement.Length - 1))
result = new
NotQuery(done(queryelement, dictionary, i + 1), dictionary);
else
if (queryelement[searchbracketmatch(queryelement, i) + 1] == "||")
result = new
OrQuery(new
NotQuery(done(queryelement, dictionary, i + 1), dictionary)
, done(queryelement, dictionary, searchbracketmatch(queryelement, i) + 2), dictionary);
else
if (queryelement[searchbracketmatch(queryelement, i) + 1] == "&&")
result = new
AndQuery(new
NotQuery(done(queryelement, dictionary, i + 1), dictionary)
, done(queryelement, dictionary, searchbracketmatch(queryelement, i) + 2), dictionary);
}
else
if (queryelement[i + 2] == "||")
result = new
OrQuery(new
NotQuery(new
NameQuery(queryelement[i + 1],dictionary), dictionary)
, done(queryelement, dictionary, i + 3), dictionary);
else
if (queryelement[i + 2] == "&&")
result = new
AndQuery(new
NotQuery(new
NameQuery(queryelement[i + 1], dictionary), dictionary)
, done(queryelement, dictionary, i + 3), dictionary);
break;
case
"(":
if (searchbracketmatch(queryelement, i) == (queryelement.Length - 1))
result = done(queryelement, dictionary, i + 1);
else
if (queryelement[searchbracketmatch(queryelement, i) + 1] == "||")
result = new
OrQuery(done(queryelement, dictionary, i + 1)
, done(queryelement, dictionary, searchbracketmatch(queryelement, i) + 2), dictionary);
else
if (queryelement[searchbracketmatch(queryelement, i) + 1] == "&&")
result = new
AndQuery(done(queryelement, dictionary, i + 1)
, done(queryelement, dictionary, searchbracketmatch(queryelement, i) + 2), dictionary);
break;
default:
if (i == (queryelement.Length - 1) || queryelement[i + 1] == ")")
result = new
NameQuery(queryelement[i], dictionary);
else
if (queryelement[i + 1] == "||")
result = new
OrQuery(new
NameQuery(queryelement[i], dictionary)
, done(queryelement, dictionary, i + 2), dictionary);
else
if (queryelement[i + 1] == "&&")
result = new
AndQuery(new
NameQuery(queryelement[i], dictionary)
, done(queryelement, dictionary, i + 2), dictionary);
break;
}
return result; //返回生成的Query
}
public
static
int searchbracketmatch(String[] queryelement, int now)
{ //查询括号匹配函数
int leftbracket = 1;
int rightbracket = 0;
int i = 0;
for (i = now + 1; i < queryelement.Length; i++)
{
if (queryelement[i] == "(")
leftbracket++;
else
if (queryelement[i] == ")")
rightbracket++;
if (leftbracket == rightbracket)
break;
}
return i; //返回对应括号在数组中的位置
}
}
现在看递归的部分简直像是rubbish啊，臃肿又难以理解。不过这个程序让我第一次体会到了面向对象编程的巨大优势，那就是多态。在程序中我不需要知道那些Objects具体是什么类型，只要用它们的基类来指向它们，并应用基类中定义的methods，不用管那么多，反正编译器回自己判断我调用的是什么类型，它是否重载了我所调用的method………….