Visual Studio Regular Expressions for Find & Replace

Visual Studio has had support for regular expressions for Find & Replace for several versions, but I've only really used it for simple searches. I recently had a problem where I needed to introduce a set of changes to a very large object model. It occurred to me that this could be greatly simplified with some pattern matching, but I was genuinely surprised to learn that Visual Studio had their own brand of Regular Expressions.

After spending some time learning the new syntax I had a really simple expression to modify all of my property setters:

Original:

public string PropertyName
{
    get { return _propertyName; }
    set
    {
        _propertyName = value;
        RaisePropertyChanged("PropertyName");
    }
}

Goal:

public string PropertyName
{
    get { return _propertyName; }
    set
    {
        if ( value == _propertyName )
             return;            
        _propertyName = value;
        RaisePropertyChanged("PropertyName");
    }
}

Here’s a quick capture and breakdown of the pattern I used.

Find:

^{:Wh*}<{_:a+} = value;

• ^ = beginning of line
• { = start of capture group #1
• :Wh = Any whitespace character
• * = zero or more occurrences
• } = end of capture group #1
• < = beginning of word
• { = start of capture group #2
• _ = I want to the text to start with an underscore
• :a = any alpha numerical character
• + = 1 or more alpha numerical characters
• } end of capture group #2
• “ = value;” = exact text match

Replace:

\1(if (\2 == value)\n\1\t\return;\n\1\2 = value;

The Replace algorithm is fairly straight forward, where “\1” and “\2” represent capture groups 1 and 2.  Since capture group #1 represents the leading whitespace, I’m using it in the replace pattern to keep the original padding and to base new lines from that point.  For example, “\n\1\t” introduces a newline, the original whitespace and then a new tab.

It’s seems insane that Microsoft implemented their own regular expression engine, but there’s some interesting things in there, such as being able to match on quoted text, etc.

I know this ain’t much, but hopefully it will inspire you to write some nifty expressions.  Cheers.