Regular Expressions Cookbook, 2nd Edition

9.15. Match INI Name-Value Pairs

Problem

You want to match INI parameter name-value pairs (e.g., Item1=Value1), separating each match into two parts using capturing groups. Backreference 1 should contain the parameter name (Item1), and backreference 2 should contain the value (Value1).

Solution

Here’s the regular expression to get the job done:

^([^=;\r\n]+)=([^;\r\n]*)

Regex options: ^ and $ match at line breaks

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Or with free-spacing mode turned on:

^               # Start of a line
( [^=;\r\n]+ )  # Capture the name to backreference 1
=               # Name-value delimiter
( [^;\r\n]* )   # Capture the value to backreference 2

Regex options: ^ and $ match at line breaks, free-spacing

Regex flavors: .NET, Java, XRegExp, PCRE, Perl, Python, Ruby

Discussion

Like the other INI recipes in this chapter, we’re working with pretty straightforward regex ingredients here. The pattern starts with ‹^›, to match the position at the start of a line (make sure the “^ and $ match at line breaks” option is enabled). This is important because without the assurance that matches start at the beginning of a line, you could match part of a commented-out line.

Next, the regex uses a capturing group that contains the negated character class ‹[^=;\r\n]› followed by the ‹+› one-or-more quantifier to match the name of the parameter and remember it as backreference 1. The negated class matches any character except the following four: equals sign, semicolon, carriage return (‹\r›), and ...