Question

Have worked in dozens of languages but new to Python.

My first (maybe second) question here, so be gentle…

Trying to efficiently convert HTML-like markdown text to wiki format (specifically, Linux Tomboy/GNote notes to Zim) and have gotten stuck on converting lists.

For a 2-level unordered list like this…

• First level
  • Second level

Tomboy/GNote uses something like…

<list><list-item>First level<list><list-item>Second level</list-item></list></list-item></list>

However, the Zim personal wiki wants that to be…

* First level
  * Second level

… with leading tabs.

I’ve explored the regex module functions re.sub(), re.match(), re.search(), etc. and found the cool Python ability to code repeating text as…

 count * "text"

Thus, it looks like there should be a way to do something like…

 newnote = re.sub("<list>", LEVEL * "\t", oldnote)

Where LEVEL is the ordinal (occurrance) of <list> in the note. It would thus be 0 for the first <list> incountered, 1 for the second, etc.

LEVEL would then be decremented each time </list> was encountered.

<list-item> tags are converted to the asterisk for the bullet (preceded by newline as appropriate) and </list-item> tags dropped.

Finally… the question…

• How do I get the value of LEVEL and use it as a tabs multiplier?

Answer 1

You should really use an xml parser to do this, but to answer your question:

import re

def next_tag(s, tag):
    i = -1
    while True:
        try:
            i = s.index(tag, i+1)
        except ValueError:
            return
        yield i

a = "<list><list-item>First level<list><list-item>Second level</list-item></list></list-item></list>"

a = a.replace("<list-item>", "* ")

for LEVEL, ind in enumerate(next_tag(a, "<list>")):
    a = re.sub("<list>", "\n" + LEVEL * "\t", a, 1)

a = a.replace("</list-item>", "")
a = a.replace("</list>", "")

print a

This will work for your example, and your example ONLY. Use an XML parser. You can use xml.dom.minidom (it’s included in Python (2.7 at least), no need to download anything):

import xml.dom.minidom

def parseList(el, lvl=0):
    txt = ""
    indent = "\t" * (lvl)
    for item in el.childNodes:
        # These are the <list-item>s: They can have text and nested <list> tag
        for subitem in item.childNodes:
            if subitem.nodeType is xml.dom.minidom.Element.TEXT_NODE:
                # This is the text before the next <list> tag
                txt += "\n" + indent + "* " + subitem.nodeValue
            else:
                # This is the next list tag, its indent level is incremented
                txt += parseList(subitem, lvl=lvl+1)
    return txt

def parseXML(s):
    doc = xml.dom.minidom.parseString(s)
    return parseList(doc.firstChild)

a = "<list><list-item>First level<list><list-item>Second level</list-item><list-item>Second level 2<list><list-item>Third level</list-item></list></list-item></list></list-item></list>"
print parseXML(a)

Output:

* First level
    * Second level
    * Second level 2
        * Third level