In the previous post, we talked about regular expression. Their implementation s quite interesting. I would like to cover that in a subsequent post. Meanwhile I wanted to mention the different forms regular expression can take. The given pattern can have wild card and meta characters. This means the patterns can match a variety of forms. Typically we need one expanded form that will match most patterns.
By expanding the regular expression I mean, we use a form which has all the different possible groups enumerated. By expanding the groups, we attempt to cover all the patterns that were intended to be matched. Recall how in our final desired output, we order the results based on groups and captures. Expanding the pattern helps us with this enumeration.
There are many editors for regular expression including Regular Expression Buddy that enables users of regular expressions to try out their expression with sample data in an interactive manner. The idea is that there may need to be some experimentation to decide which regular expression best suits the need so that there is little surprise between the  desired and actual output. Although the regular expression buddy is a downloadable software, there are webapplications such as regexpr that we can try out for the same. The User interface allows you to interactively and visually see the results with highlighted matches.