Swap Assignments Macro

Introduction

I find this useful and couldn't find anything like it before I wrote it, hence this article.

This is a simple little macro I came up with to alleviate the tedium of reversing assignments in source code. This is something I come across quite frequently when working with business objects and in ASP.NET forms where you initially set a series of objects with a value, then later want to reverse the assignment.

For example, you might want to convert this...

TextBox.Text=myobject.name; 

... to this:

myobject.name=TextBox.Text; 

Multiply that by dozens of assignments and it's quite tedious to reverse all that original code you wrote. Since this is very simple, I've just included it here in the article content. You can copy and paste it into your own macro in Visual Studio.

Note that it appends each line of code with a semicolon for C#, but you could easily modify it to not do that for VB or whatever you happen to be editing.

Imports System
Imports EnvDTE
Imports EnvDTE80
Imports System.Diagnostics
Imports System.Text
Imports System.Text.RegularExpressions   

Public Module JohnUtils
    'Get currently selected text function
    Private Function GetCurrentlySelectedText() As String
        If Not DTE.ActiveDocument Is Nothing Then
            Dim txt As TextSelection
            txt = CType(DTE.ActiveDocument.Selection, TextSelection)
            Return txt.Text
        Else
            Return String.Empty
        End If
    End Function 
    'Swap assignments, go through each line in the currently selected text
    'and swap the left and right side and output as a block below the selected text
    Sub SwapAssignmentRegion()
        Dim line, originalCode As String
        originalCode = GetCurrentlySelectedText()
        If Not originalCode = String.Empty Then
            Dim leftside As String
            Dim rightside As String
            Dim output As New System.Text.StringBuilder
            Dim lines() As String
            lines = Split(originalCode, vbLf)
            Dim r As Regex
            'Use a regular expression to parse out the text on either side of
            'the equals sign in the line being processed
            r = New Regex( _
                "\s*(?<leftside>\S*)" & _
                "\s*(=)\s*(?<rightside>\S*)", _
                RegexOptions.IgnoreCase Or _
                RegexOptions.ExplicitCapture) 
            For Each line In lines
                line = line.Trim
                If Not line = String.Empty Then
                    Dim mtch As Match
                    mtch = r.Match(line)
                    If mtch.Success Then
                        leftside = _
                          mtch.Groups("leftside").Value.Trim
                        rightside = _
                          mtch.Groups("rightside").Value.Trim.Replace(";", "")
                        'Remove the semicolon replace statement above and 
                        'in the output format below for VB
                        output.AppendFormat( _
                               "{0}{1} = {2};", _
                             vbCrLf, rightside, _
                             leftside)
                    End If
                End If
            Next 
            'Output the swapped region with undo context
            'so user can undo the whole operation at once
            DTE.UndoContext.Open("SwapAssignmentRegion")
            Dim txt As TextSelection
            txt = CType(DTE.ActiveDocument.Selection, TextSelection)
            txt.Insert(vbCrLf + output.ToString, _
                vsInsertFlags.vsInsertFlagsInsertAtEnd _
                Or vsInsertFlags.vsInsertFlagsContainNewText)
            txt.SmartFormat()
            DTE.UndoContext.Close() 
        End If 
    End Sub 
End Module

History

• 20^th September, 2006: Initial post