Matching Multiline Blocks Using Regular Expressions

You may encounter difficulties when matching against text that spans multiple lines using Python's regular expressions. Consider the following example text:

some Varying TEXT

DSJFKDAFJKDAFJDSAKFJADSFLKDLAFKDSAF
[more of the above, ending with a newline]
[yep, there is a variable number of lines here]

(repeat the above a few hundred times).

The goal is to capture two components:

• "some Varying TEXT"
• All uppercase lines located two lines beneath it (excluding any newline characters)

Several approaches have been attempted unsuccessfully:

re.compile(r"^>(\w )$$(\n[.$] )^$", re.MULTILINE) # Capture both parts
re.compile(r"([^>][\w\s] )$", re.MULTILINE|re.DOTALL) # Just textlines

To address this issue, utilize the following regular expression:

re.compile(r"^(. )\n((?:\n. ) )", re.MULTILINE)

Keep in mind that anchors "^" and "$" do not match linefeeds. Hence, in multiline mode, "^" follows a newline, and "$" precedes a newline.

Furthermore, be mindful of various newline formats. For text that may contain linefeeds, carriage-returns, or both, employ this more inclusive regex:

re.compile(r"^(. )(?:\n|\r\n?)((?:(?:\n|\r\n?). ) )", re.MULTILINE)

The DOTALL modifier is unnecessary here because the dot already excludes newlines.