Getting node from line number in Roslyn

Question

How can I get a SyntaxNode based on a line number? Else if its possible to get LineSpan of that line number then to node.

Answer 1

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Text;

var s =  @"class M
{
    public void P() { }
}";
var text = SourceText.From(s);
var lineIndex = 2;
var lineSpan = text.Lines[lineIndex].Span;
var tree = SyntaxFactory.ParseSyntaxTree(text);
var node = tree.GetRoot().FindNode(lineSpan);
// or if you want a all nodes related to the span
var node = tree.GetRoot().DescendantNodesAndSelf(lineSpan);

Answer 2

You can get the span of a line from the document text. From there, you can find all nodes that intersect with the span of the line. This will return multiple syntax nodes, which you can then use your criteria to pull out the one you are looking for:

    static void Main(string[] args)
    {
        var code = @"
using System;

namespace ConsoleApplication1
{
    class TypeName
    {   
         public int Add(int x, int y) 
         {
             return x+y;
         }
     }
}";
        var st = SourceText.From(code);
        var sf = SyntaxFactory.ParseSyntaxTree(st);

        var span = sf.GetText().Lines[9].Span;
        var nodes = sf.GetRoot().DescendantNodes().Where(x => x.Span.IntersectsWith(span));

        Console.WriteLine(nodes.Last().ToString());
        Console.ReadKey();
    }