搜索模式

Question

I need to search a list for some pattern is present or not.

var result=roles.Where(z=>z.Contains(x) && z.Contains(y)).ToList();

string x = "Resource:resource1:resource2";
string y = "writer";
List<string> roles=new List<string>{"Resource::reader","Resource:resource1::Deleter","Resource:resource1::writer"};

I need to find if any value is present in roles list like:

Resource::writer or Resource:resource1::writer or Resource:resource1:resource2::writer ie Split x based on : and append y to the combination of splitted x

Answer 1

If my understanding of your problem is right :

You have a list which can contain anything that you names roles. Thoses roles are in format A::B or A:B::C or A:B:C::D etc...

And what you want to achieve is to find if any "path" or combination of path from x can give the role y ?

for instance : if you have roles like A::ZA::YA:B::XA:B:C::X

you have x which is A:B:C

and you have y which is X

you want to check is you have A::X in the list

if you don't, you're gonna check A:B::X in the list,

and if you still don't, you will look for A:B:C::X

So again if I'm right, you could consider something like this :

        String path = "A:B:C";
        String roleNeeded = "X";
        List<String> roles = new List<string>() { "A::Z", "A::Y", "A:B::X" };

        List<String> pathStep = new List<string>();
        pathStep = path.Split(':').ToList();

        String lookupPath = String.Empty;
        String result = String.Empty;
        pathStep.ForEach( s =>
        {
            lookupPath += s;
            if (roles.Contains(lookupPath + "::" + roleNeeded))
            {
                result = lookupPath + "::" + roleNeeded;
            }
            lookupPath += ":";
        });

        if (result != String.Empty)
        {
            // result is Good_Path::Role
        }

This way you start spliting your path X as a list and you aggregate it in the foreach to look at each step.

Answer 2

You should consider using Regular Expression. Try this out,

 string x = "Resource:resource1:resource2"; string y = "writer"; List<string> roles; List<string> words = new List<string> { x, y }; // We are using escape to search for multiple strings. string pattern = string.Join("|", words.Select(w => Regex.Escape(w))); Regex regex = new Regex(pattern, RegexOptions.IgnoreCase); // You got matched results... List<string> matchedResults = roles.Where(regex.IsMatch).ToList(); 

Answer 3

        string x = "Resource:resource1:resource2";
        string y = "writer";
        List<string> roles = new List<string>
        {
            "Resource::writer",
            "Resource:resource1:resource2::writer"
        };

        var records = x.Split(':').Select((word, index) => new { word, index });

        var result =
            from record in records 
            let words = $"{string.Join(":", records.Take(record.index + 1).Select(r => r.word))}::{y}"
            join role in roles on words equals role
            select words;