Futese

未來

“未來”代表fu ll te x s se拱門。

這是一個簡單的內存持久性全文搜索引擎，不到1000行C＃代碼：

• 索引部分令牌字符串，並在索引中添加相應的鍵
• 索引令牌是可自定義的。默認情況下，它消除了變音符號，並存儲僅小寫
• 查詢部分可以搜索短語。它支持和（blah blih），或（blah | blih）而不是（blah -blih）
• 該索引可以保存到流（或文件）並重新加載
• 提供了使用鎖（ ThreadSafeIndex<T> ）和使用ContrentDictionary（ ConcurrentIndex<T> ）的並發版本的線程安全率。 ConcurrentIndex<T>使用更多的內存。
• 您可以使用非線程安全版本進行索引，將其保存並使用線程安全版本加載
• 整個代碼也可作為單個.cs文件提供：futese.cs

 // create an index with string keys
var index = new Index<string>();

// add keys and phrases
index.Add("a", "This is a simple phrase");
index.Add("b", "And this one is another phrase a bit longer");
index.Add("c", "The last phrase (this one) contains french (with diacritics) like 'réveillez-vous à l'heure!'");

// search
SimpleTest(index);

// persist to a file
var fileName = "test.fts";
index.Save(fileName);

// load from a file
var newIndex = new Index<string>();  // or new ThreadSafe<string>() for example
newIndex.Load(fileName);

// search again
SimpleTest(newIndex);

newIndex.KeysCount.Should().Be(index.KeysCount);

 static void SimpleTest(Index<string> index)
{
    string[] result;
    result = index.Search("this").Distinct().ToArray();
    result.Should().BeEquivalentTo(["a", "b", "c"]);

    result = index.Search("this is").Distinct().ToArray();
    result.Should().BeEquivalentTo(["a", "b"]);

    result = index.Search("simple | with").Distinct().ToArray();
    result.Should().BeEquivalentTo(["a", "c"]);

    result = index.Search("that").Distinct().ToArray();
    result.Should().BeEquivalentTo([]);

    result = index.Search("the").Distinct().ToArray();
    result.Should().BeEquivalentTo(["c"]);

    result = index.Search("rev").Distinct().ToArray();
    result.Should().BeEquivalentTo(["c"]);

    result = index.Search("-one").Distinct().ToArray();
    result.Should().BeEquivalentTo(["a"]);

    result = index.Search("-this | last").Distinct().ToArray();
    result.Should().BeEquivalentTo([]);
}

您也可以使用複雜的密鑰，例如，該Customer類可以用作密鑰，並且其數據也將被持續使用：

 // a key must be IParsable and should generally implement IEquatable<T>
private sealed class Customer(int id, string firstName, string lastName, int age) :
    IParsable<Customer>, IEquatable<Customer>
{
    public int Id => id;
    public string FirstName => firstName;
    public string LastName => lastName;
    public int Age => age;

    // used when saved to a stream.
    // by default, the index will use object.ToString() to persist the key,
    // but you can also implement IStringable.ToString()
    public override string ToString() => id + "t" + firstName + "t" + lastName + "t" + age;

    // use id as the real key
    public override int GetHashCode() => id.GetHashCode();
    public override bool Equals(object? obj) => Equals(obj as Customer);
    public bool Equals(Customer? other) => other != null && other.Id == id;

    // used when loading from a stream
    public static Customer Parse(string s, IFormatProvider? provider)
    {
        var split = s.Split('t');
        return new Customer(int.Parse(split[0]), split[1], split[2], int.Parse(split[3]));
    }

    // not called by futese which expects Parse to succeed
    public static bool TryParse([NotNullWhen(true)] string? s, IFormatProvider? provider, [MaybeNullWhen(false)] out Customer result) => throw new NotImplementedException();
}

這就是您的使用方式：

 var index = new Index<Customer>();

index.Add(new(0, "alice", "hunting-bobby-crown", 25));
index.Add(new(1, "bob", "albert-down", 32));
index.Add(new(2, "carl", "ctrl-alt", 15));

// search
TestWithObjects(index);

// persist to a file
var fileName = "customer.fts";
index.Save(fileName);

// load from a file
var newIndex = new Index<Customer>();
newIndex.Load(fileName);

// search again
TestWithObjects(newIndex);

 static void TestWithObjects(Index<Customer> index)
{
    Customer[] result;
    result = index.Search("al").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "alice" || c.FirstName == "bob" || c.FirstName == "carl");

    result = index.Search("b").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "alice" || c.FirstName == "bob");

    result = index.Search("a -c").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "bob");

    result = index.Search("a c").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "alice" || c.FirstName == "carl");

    result = index.Search("a d").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "bob");

    result = index.Search("hunting a").Distinct().ToArray();
    result.Should().OnlyContain(c => c.FirstName == "alice");
}