如何使用Roslyn检测类是否使用Linq？

Question

Using Roslyn , I would like to detect if a class uses Linq .

Assuming some code like:

//...
int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };       
var lowNums = 
    from n in numbers 
    where n < 5 
    select n; 
//...

Assume also that the file this code does not include using System.Linq;

I would like to be able to detect that there is a linq statement in the file and (say) automatically add using System.Linq . I would like to detect either query or method syntax for Linq.

Is there a way I can detect this using Roslyn? I just want to know if the code is using Linq or not, and dont want to do any further processing.

Answer 1

Given a syntax tree, you can simply search for nodes of SyntaxKind.QueryExpression or related node types.

For more information, open the file in VS2015 and look at the syntax visualizer to see exactly what the syntax tree looks like.