Fenceposts

Environment: VisualStudio 6.0

The EPM text editor under OS/2 provided a macro facility not unlike that in DevStudio,
which meant that before it had been around for long, a number of really useful macros
started popping up on internet sites that catered to OS/2 users. One particular set of
macros that I have really been missing since moving off of that platform is called
“Fenceposts” (though I am not entirely sure that was the original name). The family of
DevStudio macros presented here, duplicates this feature.

So what’s a fencepost?

A fencepost contains a filename and cursor position (row and column coordinates) within
the active document of your current DevStudio project. That is, it completely
describes a location within your sourcecode. Fenceposts can be planted, and they can
be pulled. Planting a fencepost saves this location information within the fencepost
stack. Pulling a fencepost then returns the editor to the most recently planted
fencepost, activating and opening documents as necessary, and removes that information
from the stack.

I find this kind of sourcecode navigation very useful, especially in a deeply nested
class hierarchy.

'------------------------------------------------------------------------------
'FILE DESCRIPTION: Provide a stack for storing edit locations
'
'NOTES:
'*  Access to the postfile is very rudimentary -- the file is
'   read completely, modified and rewritten when posts are
'   added or removed. There is probably a better way, but that
'   was the first method I found.
'*  I would like to add a 'Beep' when PullFencepost has nothing
'   to do, but DevStudio provides no way to do this that I know
'   of.
'------------------------------------------------------------------------------

Sub SetDefaultFencepostKeyBindings()
'DESCRIPTION: Setup default key mappings for fencepost macros.
'This is simply an installation routine

    AddKeyBinding "Ctrl+Shift+NumPad Clear", "ClearFencepostStack", "Text"
    AddKeyBinding "Ctrl+Shift+Down Arrow", "PlantFencepost", "Text"
    AddKeyBinding "Ctrl+Shift+Up Arrow", "PullFencepost", "Text"
End Sub

Function postfilePathname()
'DESCRIPTION: File where fenceposts are stored.
'The postfile lives in the ActiveProject directory, so the
'pathname is built from that.

    str = Application.ActiveProject.FullName
    pos = InStrRev(str, "")
    str = Left(str, pos)
    postfilePathname = str + "_postfile.dat"
End Function

Sub PlantFencepost()
'DESCRIPTION: Save current location on an in-file stack for later.

    'Access the filesystem
    Set fso = CreateObject("Scripting.FileSystemObject")
    fencepostfile = postfilePathname()

    'If postfile exists, read into block
    If (fso.fileexists(fencepostfile)) Then
        Set f = fso.GetFile(fencepostfile)
        Set a = f.OpenAsTextStream(1)
        If f.Size > 0 Then
            block = a.readall
        End If
        a.Close
    End If

    'Build Fencepost
    fencepost = ActiveDocument.FullName _
        + "(" + CStr(ActiveDocument.Selection.CurrentLine) _
        + ":" + CStr(ActiveDocument.Selection.CurrentColumn) _
        + ")"

    'Prepend fencepost to fencepost block
    block = fencepost + vbNewLine + block

    'Write the block to file
    Set a = fso.CreateTextFile(fencepostfile, True)
    a.write (block)
    a.Close
End Sub

Sub PullFencepost()
'DESCRIPTION: Retrieve a previous location from the in-file stack.

    'Access the filesystem
    Set fso = CreateObject("Scripting.FileSystemObject")
    fencepostfile = postfilePathname()

    'If the file exists...
    If (fso.fileexists(fencepostfile)) Then
        Set f = fso.GetFile(fencepostfile)
        Set a = f.OpenAsTextStream(1)

        '...and if there are records to read
        If f.Size > 0 Then

            'Read the file
            block = a.readall
            pos = InStr(block, vbNewLine)
            Line = Left(block, pos)
            block = Mid(block, pos + 2)
            a.Close

            'Write the modified fencepost block
            Set a = fso.CreateTextFile(fencepostfile, True)
            a.write (block)
            a.Close

            'If there is anything in the line
            If Len(Line) > 0 Then
                'Parse the line into something like:
                'fname(lineNum,ColNum)
                pos = InStr(Line, "(")
                fname = Left(Line, pos - 1)
                Line = Mid(Line, pos + 1)
                pos = InStr(Line, ":")
                lineNum = CInt(Left(Line, pos - 1))
                Line = Mid(Line, pos + 1)
                pos = InStr(Line, ")")
                colNum = CInt(Left(Line, pos - 1))

                'Open or surface the given document
                Set doc = Documents.open(fname)

                'Move to the proper location
                doc.Selection.moveTo lineNum,colNum

                'moving the cursor around gives us some
                'context around our post location
                doc.Selection.lineDown dsMove,3
                doc.Selection.lineUp dsMove,6

                'Move to the proper location again
                doc.Selection.moveTo lineNum,colNum
            End If
        End If
    End If
End Sub

Sub ClearFencepostStack()
'DESCRIPTION: Remove all entries from the fencepost stack
    Set fso = CreateObject("Scripting.FileSystemObject")
    fencepostfile = postfilePathname()
    Set a = fso.CreateTextFile(fencepostfile, True)
    a.Close
    MsgBox "Fenceposts cleared"
End Sub