How to find title a la reStructuredText

Question

Is there a regex pattern to match titles in the following reStructuredText -like text ? The difficulty is that the numbers of equal signs must be equal to the length of the title.

Some basic text.


=========
One Title
=========

For titles the numbers of sign `=` must be equal to the length of the text title. 


============= 
Another title
============= 

And so on...

Answer 1

Search for match(es) of (?:^|\\n)(=+)\\r?\\n(?!=)([^\\n\\r]+)\\r?\\n(=+)(?:\\r?\\n|$) . If match found, check if lengths of first, second and third groups are same. If so, title is a content of second group.

Answer 2

To support full syntax for section titles , you could use docutils package :

#!/usr/bin/env python3
"""
some text

=====
Title
=====
Subtitle
--------

Titles are underlined (or over- and underlined) with a printing
nonalphanumeric 7-bit ASCII character. Recommended choices are "``= -
` : ' " ~ ^ _ * + # < >``".  The underline/overline must be at least
as long as the title text.

A lone top-level (sub)section is lifted up to be the document's (sub)title.
"""
from docutils.core import publish_doctree

def section_title(node):
    """Whether `node` is a section title.

    Note: it DOES NOT include document title!
    """
    try:
        return node.parent.tagname == "section" and node.tagname == "title"
    except AttributeError:
        return None # not a section title

# get document tree
doctree = publish_doctree(__doc__)    
titles = doctree.traverse(condition=section_title)
print("\n".join([t.astext() for t in titles]))

Output:

Title
Subtitle