Mastering Regular Expressions
As this book shows, a command of regular expressions is an invaluable skill. Regular expressions allow you to code complex and subtle text processing that you never imagined could be automated. Regular expressions can save you time and aggravation. They can be used to craft elegant solutions to a wide range of problems. Once you've mastered regular expressions, they'll become an invaluable part of your toolkit. You will wonder how you ever got by without them.
The expression in parenthesis is a positive look ahead. It seeks a single open parenthesis. The to slash s expressions will seek whatever non space characters precede the parenthesis by zero or more spaces.