function Get-RoslynVisitMethods {

    Add-Type -Path "C:\Program Files\Reference Assemblies\Microsoft\Roslyn\v1.0\Roslyn.Compilers.CSharp.dll"

    [Roslyn.Compilers.CSharp.SyntaxVisitor].GetMethods("NonPublic,Instance") |
        Where {$_.name -like 'Visit*'}
}

$code = @"
using System;
using System.Management.Automation;
using Roslyn.Compilers.CSharp;

public class PSRoslynWalker : SyntaxWalker
{
    PSObject module;
    public PSRoslynWalker(PSObject module) {
        this.module = module;
    }

$(
Get-RoslynVisitMethods |
    ForEach {
    @"
   protected override void $($_.name) ($($_.GetParameters()[0].ParameterType.Name) node)
    {
        var method = module.Methods["$($_.name)"];
        if (method != null)
        {
            method.Invoke(node);
        }

        base.$($_.name)(node);
    }

"@
    }
)
}
"@


$r = "C:\Program Files\Reference Assemblies\Microsoft\Roslyn\v1.0\Roslyn.Compilers.dll",
     "C:\Program Files\Reference Assemblies\Microsoft\Roslyn\v1.0\Roslyn.Compilers.CSharp.dll"

Add-Type -TypeDefinition $Code -ReferencedAssemblies $r

$m = New-Module -AsCustomObject {

    $script:classNames = @()

    function VisitClassDeclaration ($node) {
        $script:classNames +=  New-Object PSObject -Property @{
            Name = $node.Identifier.Value
        }
    }

    function GetClassName {$script:classNames}
}

cls

$targetDirectory = "C:\downloads\NuGet\nuget_47b7cea8ff2a"
dir $targetDirectory -Recurse *.cs | % {
    $fileName = $_.FullName
    $source   = [IO.File]::ReadAllText($fileName)
    $tree     = [Roslyn.Compilers.CSharp.SyntaxTree]::ParseCompilationUnit($source, "", $null, (New-Object System.Threading.CancellationToken) )
    $obj      = New-Object PSRoslynWalker $m
    $obj.Visit($tree.Root)
}

$m.GetClassName() | Sort Name