[Visual Studio Extensibility] Adding/Installing snippets programmatically

Question

Hi,

I would like to fill a custom completion set/expansion menu with code snippets obtained from a server.

Is there a way to create snippet completion items programmatically without the need to create XML files?
I'm looking for something like VS Code has with CompletionItem and CompletionItemKind.Snippet.

Thank you!

Answer 1

So I finally found a way to do in-memory snippets.

The solution can be divided into two parts:

• The completion session with the known completion dropdown
• The snippet session, which allows switching between literals and so on

1 Provide custom completion
For the first part, I used this example of the AsyncCompletion.

2 Starting expansion session with in-memory snippet
For the snippet session I found a method on IVsExpansion called InsertSpecificExpansion (see documentation)
This allows starting an expansion session with an in-memory XMLDOMNode. To be able to use this with my custom in memory snippet structure I had to do the following:

• Create a serializable C#-Model for the Visual Studio Snippet Schema
• Parse my custom snippets to that VS-Model
• Use XML Serializer to create a IXMLDOMNode

3 Link the parts together
In order to link the two parts, I used the following approach: When a CompletionItem is chosen from the list, I cancel the regular completion and instead perform a ExpansionSession.
First I had to add an additional Property to the CompletionItem so that the ExpansionSession later can access the XMLNode:

completionItem.Properties.AddProperty("SnippetXML", snippetXMLNode);  

This can later be used by the ExpansionSession to provide the node Parameter of InsertSpecificExpansion

In CommitManager.TryCommit I first start the ExpansionSession and mark the CompletionSession as handled so no further actions are done:

        // use IVsEditorAdaptersFactoryService to get access to IVsTextview  
	var vsTextView = VsEditorAdapter.GetViewAdapter(session.TextView);  
	// start a snippet session using in-memory XML rather than .xml files  
	ExpansionClient.StartExpansion(vsTextView, item);  

	// we handled the completion by starting an expansion session so no other handlers should participate  
	return CommitResult.Handled;  

The ExpansionClient is an implementation of IOleCommandTarget and IVsExpansionClient. The Expansion follows the approach described here but the difference is it calls InsertSpecificExpansion instead of InsertNamedExpansion.

I hope this may help anyone with the same problem. At some point, I will add a complete example on GitHub.