How do you check if a variable is used in a project programmatically?

Question

In VB.NET (or C#) how can I determine programmatically if a public variable in class helper.vb is used anywhere within a project?

Thanks in advance.

Answer 1

You would need to use reflection and it would be complicated.

Why are you doing this programmaticly? You know that Visual Studio has a "Find all References" feature that can do this for you.

Answer 2

Find all References is your friend.

Answer 3

Reflector has the Analyze feature. Or, is this some sort of run time functionality you are after?

Answer 4

It has to be programmaticly. I'm writing an Add-In that would go through a project and would write the helper.vb's public properties/variables to a text file ONLY if they're used anywhere in the project.

Answer 5

Are you talking about doing this before the code is compiled? Doing this against a compiled assembly would probably not be trivial, though tools like Mono.Cecil could help. You would have to actually walk each method and inspect the IL instructions for calls to the get and set methods of the property in question. It might not actually be that bad though, especially if you used Cecil instead of System.Reflection. Cecil is also much faster, as it treats assemblies as files rather than actually loading them into the application domain.

If you're wanting to run this on the actual source code of a project things are a lot different. I don't know much about Visual Studio Add-Ins, but you might be able to invoke the "Find all references" command programmatically and use the results.

There might also be something in System.CodeDom that could help. It looks like you could use a CodeParser to parse the code into a CodeCompileUnit, and then from there walk all of the statements in all of the methods and check for related CodePropertyReferenceExpressions.

Answer 6

Thanks Nick,

I will take a look at the System.CodeDom. In the mean time, is it really possible to invoke "Find All references" programaticlly and use its results? If it is, then that would pretty much be sufficient for what I want.

Answer 7

From MSDN

The Find object allows you to search for and replace text in places of the environment that support such operations, such as the Code editor.

It is intended primarily for macro recording purposes. The editor's macro recording mechanism uses Find rather than TextSelection.FindPattern so that you can discover the global find functionality, and because it generally is more useful than using the TextSelection Object for such operations as Find-in-files.

If the search operation is asynchronous, such as Find All, then the FindDone Event occurs when the operation completes.

Sub ActionExample()
   Dim objFind As Find = objTextDoc.DTE.Find

   ' Set the find options.
   objFind.Action = vsFindAction.vsFindActionFindAll
   objFind.Backwards = False
   objFind.FilesOfType = "*.vb"
   objFind.FindWhat = "<Variable>"
   objFind.KeepModifiedDocumentsOpen = False
   objFind.MatchCase = True
   objFind.MatchInHiddenText = True
   objFind.MatchWholeWord = True
   objFind.PatternSyntax = vsFindPatternSyntax.vsFindPatternSyntaxLiteral
   objFind.ResultsLocation = vsFindResultsLocation.vsFindResultsNone
   objFind.SearchPath = "c:\<Your>\<Project>\<Path>"
   objFind.SearchSubfolders = False
   objFind.Target = vsFindTarget.vsFindTargetCurrentDocument
   ' Perform the Find operation.
   objFind.Execute()
End Sub



<System.ContextStaticAttribute()> _
Public WithEvents FindEvents As EnvDTE.FindEvents

Public Sub FindEvents_FindDone(ByVal Result As EnvDTE.vsFindResult, _
                               ByVal Cancelled As Boolean) _
                               Handles FindEvents.FindDone
   Select Case Result 
        case vsFindResultFound
             'Found!
        case else
             'Not Found
   Ens select
End Sub