[SOLVED] How to determine the ProjectItem language type without opening the document in vsx?

How to determine the ProjectItem language type without opening the document in vsx?

When a file is open in the visual studio editor, through the EnvDTE.Document.Language property a string result such as "CSharp", "C/C++", "HTML", "JScript", etc. is returned specifying the language of a file. I'd like to be able to access that same language information when a file is not open (i.e. from a ProjectItem context).

EnvDTE.ProjectItem.FileCodeModel.Language seemed promising, but only gave me a result for CSharp files. No information was available for HTML, XAML, etc.

I could make assumptions based on file extensions, but being able to retrieve the language as interpreted by Visual Studio (presumably through the language service(s)) would be a lot more robust. It seems like the information is available since it is stored on the document, but I haven't been able to find the right API for accessing it.

Any help or suggestions would be greatly appreciated. :)

Solution

For anyone else who may stumble upon this, I found an approach that will work. I'm still interested to hear if anyone has a cleaner solution.

Import the Microsoft.VisualStudio.Package.LanguageService.9.0 (or equivalent) assembly.
Instantiate an EditorFactory
Call GetLanguageService on the EditorFactory instance, passing the extension of the project item (i.e. System.IO.Path.GetExtension(ProjectItem.Name))
Compare the returned language service GUID against known constants. You can dig these out of your registry under HKEY_USERS\.DEFAULT\Software\Microsoft\VisualStudio\10.0_Config\Languages\Language Services (or equivalent)

Here are the language service guids I found to save someone else the trouble of looking them up:

CSharp: "{694DD9B6-B865-4C5B-AD85-86356E9C88DC}"
C/C++: "{B2F072B0-ABC1-11D0-9D62-00C04FD9DFD9}"
CSS: "{A764E898-518D-11d2-9A89-00C04F79EFC3}"
HTML: "{58E975A0-F8FE-11D2-A6AE-00104BCC7269}"
JScript: "{59E2F421-410A-4fc9-9803-1F4E79216BE8}"
XAML: "{c9164055-039b-4669-832d-f257bd5554d4}"
XML: "{f6819a78-a205-47b5-be1c-675b3c7f0b8e}"

Note: I found that the JScript language service was incorrectly mapped to HTML by default.