Regular expressions, or regex, are powerful tools used in Workiva Chains to identify and manipulate patterns in text data. Think of regex as a search or search and replace tool that helps you extract specific information or format data consistently. Whether parsing reports, cleaning datasets, or automating workflows, regex is an essential resource for handling complex text based tasks efficiently in Chains.

Regex is commonly used in Chains within Commands like File Utilities (Find, Find and Replace, Move) and Tabular Transformation (Column Filter, Filter Rows, Find and Replace, Join Columns). It is also very useful in building Command Dynamic Outputs and Chain Outputs.

Chains include a test feature to evaluate regex match types. For instance, when creating a Command Dynamic Output, the "TEST" button at the top right allows you to validate your regular expressions. You can also use online tools such as regex101.com and regexr.com to refine your regex.

Below is a getting started overview to regular expressions. For a deeper review, see Regular Expression Operators.

Regex Basics

• Dot (.): Matches any character except line breaks
• Line Breaks and Whitespace (\n, \r, \s, \S): \n match line feeds, \r match carriage returns, \s matches whitespace, \S matches non-whitespace characters
• Word Characters (\w, \W): \w matches letters, digits, and underscores; \W matches everything else
• Digit Characters (\d, \D): \d matches digits; \D matches non-digit characters
• Anchors (^, $): ^ matches the start of a string or line; $ matches the end, e.g., ^T
• Escaped Characters (\): Escape special characters like . or * with \. For example, \.

Character Sets

• Selected Sets ([ ]): Match any character within brackets, e.g., [qui]
• Negated Sets ([^ ]): Match characters not listed, e.g., [^qui]
• Ranges (a-z, A-Z, 0-9): Match characters within a range, e.g., [a-z]

Groups and Lookaheads

• Capture Groups (( )): Capture matched text for extraction, e.g., (one)
  
• Non-Capture Groups ((?: )): Group tokens without capturing, e.g., (?:one)
• Lookaheads (?=, ?!): Positive (?=) matches when followed by a pattern; negative (?!) matches when not followed. Examples, \s(?=one) and \s(?!one)

Quantifiers

• Greedy Quantifiers: + (one or more) e.g., [A-Z]\w+; * (zero or more) e.g., [A-Z][a-z]*; {n} (exactly n times) e.g., [A-Z][a-z]{3}; {n,} (n or more times) e.g., [A-Z][a-z]{3,}; {n,m} (between n and m times) e.g., [A-Z][a-z]{3,4}
• Lazy Quantifier (?): Matches as few characters as possible, e.g., \w?e

Practical Examples

• US ZIP Code: (^\d{5}$)
• US ZIP+4: (^\d{5})-?(\d{4}$)?
• US Phone Number: (\+\d)?[ .-]?\(?(\d{3})\)?[ .-]?(\d{3})[ .-]?(\d{4}$)