[SDK Package] Get the word at where the caret is

Technical Info

• Visual Studio SDK Version: 2013
• Windows Version: 8.1 x64
• Development Language: VB.Net and also C#

Question

How I could get and replace the current word in the code editor? I mean the full word at where the caret is, not the selection text.

This is a pseudo-code of what I try to do:

Dim caret As ITextCaret = Tools.GetCurrentViewHost.TextView.Caret
Dim span As Span = caret.ContainingTextViewLine.Extent.Span
Dim snapshot As ITextSnapshot = caret.ContainingTextViewLine.Extent.Snapshot
Dim word As String =  ...?

snapshot.TextBuffer.Replace(span, word & "some text"))

Research

I've tried to figure it out researching the members of Microsoft.VisualStudio.Text.Editor.Caret without success.

I also seen a random code in MSDN which I'm not sure if it is related with this issue, anyways I cannot figure out what I should use asm_provider object:

https://msdn.microsoft.com/en-us/library/ff926100.aspx?f=255&MSPPError=-2147217396

'neither an expansion session nor a completion session is open, but we got a tab, so check whether the last word typed is a snippet shortcut
If m_session Is Nothing AndAlso m_exSession Is Nothing AndAlso nCmdID = CUInt(VSConstants.VSStd2KCmdID.TAB) Then
    'get the word that was just added
    Dim pos As CaretPosition = m_textView.Caret.Position
    Dim word As TextExtent = m_provider.NavigatorService.GetTextStructureNavigator(m_textView.TextBuffer).GetExtentOfWord(pos.BufferPosition - 1)
    Dim textString As String = word.Span.GetText()
    'if it is a code snippet, insert it, otherwise carry on
    If InsertAnyExpansion(textString, Nothing, Nothing) Then
        Return VSConstants.S_OK
    End If
End If