New line breaks custom markdown extension - regex

Question

I'm writing an extension for python-markdown, that is supposed to put the text inside some custom tags of mine into a styled div.
I have created a simple Inline Pattern class that encapsulates matched expression in a div tag. My regex is as follows: r'(\{mytag_start\})(.+)(\{mytag_end\})' which then is put inside "^(.*?) --- (.*?)$" by the markdown.inlinepatterns.Pattern class upon compilation, so that the compile method is called as re.compile("^(.*?)%s(.*?)$" %r'(\{mytag_start\})(.+)(\{mytag_end\})').
At a first glance this does seem to do the trick, however I've noticed that all line breaks need to be hardcoded as <br> tags.
So
{mytag_start}This code<br>
will work{mytag_end}
However, the following code breaks the entire markdown
{mytag_start}This code
will not{mytag_end}
So instead I just get the entire above block unprocessed in plain text.
I tried supplying re.MULTILINE and re.DOTALL to the re.compile but it didn't help. Any ideas?
EDIT: Here is a sample extension file that exhibits the aforementioned problems. I then load the extension in my django template using {{ content:"mdx_MyExtension"}}.

Answer 1

Try using a non-greedy operator (+immediately followed by ?) :
r'(\{mytag_start\})(.+?)(\{mytag_end\})'
Full regex :
^(?:.*?)(\{mytag_start\})(.+?)(\{mytag_end\})(?:.*?)$
Flags :
DOTALL, IGNORECASE, MULTILINE
Data test :
blah
blash
<h1>Title</h1>
{mytag_start}This code<br>
will work{mytag_end}
<b>bold</b>
{mytag_start}This code
will not{mytag_end}
Output :
# Run findall
>>> regex.findall(string)
[(u'{mytag_start}', u'This code<br>\nwill work', u'{mytag_end}'), (u'{mytag_start}', u'This code\n\nwill not', u'{mytag_end}')]