Question

I use a permanent set of about eleven regular expressions to parse about 80k – 200k characters long strings. So far I just used new Regex(@"blah") in every place where I had to use Match(String, Int32), Replace(String, String) and Replace(String, MatchEvaluator).

But using these instance methods does not take advantage of the .NET’s regular expressions cache. So I want to refactor my code to use static methods instead. The problem is I can’t find a static equivalent of Match(String, Int32).

I thought about just using String.Substring(Int32) as appropriate but as far as I know it would allocate new String for me.

Do I have some other options?

Answer 1

You can create a static instance of the 11 regexes and use it everywhere.

static Regex r= new Regex(...);

Or you can create a static singleton object which contains the regexes.

public MyStaticObject{
    private  Regex r1;
    private  Regex r2;

    public Regex R1{
        get{ return r1;}
    }
    //...
    private MyStaticObject instance;

    private MyStaticObject(){
        r1=new Regex(...);
    }

    public MyStaticObject GetInstance(){
        if(instance==null){
            instance= new MyStaticObject();
        }
        return instance;
    }
}