I am looking for a free (as in freedom) HTML indenter (or re-indenter) written in Python (module or command line). I don't need to filter HTML with a white list. I just want to indent (or re-indent) HTML source to make it more readable. For example, say I have the开发者_高级运维 following code:

<ul><li>Item</li><li>Item
</li></ul>

the output could be something like:

<ul>
    <li>Item</li>
    <li>Item</li>
</ul>

Note: I am not looking for an interface to a non-Python software (for example Tidy, written in C), but a 100% Python script.

Thanks a lot.

---

you can use the built-in module xml.dom.minidom's toprettyxml function:

>>> from xml.dom import minidom
>>> x = minidom.parseString("<ul><li>Item</li><li>Item\n</li></ul>")
>>> print x.toprettyxml()
<?xml version="1.0" ?>
<ul>
    <li>
        Item
    </li>
    <li>
        Item
    </li>
</ul>

---

Using BeautifulSoup

There are a dozen ways to use the BeautifulSoup module and it's prettify function. Here are some examples to get you started.

From the Commandline

$ python -m BeautifulSoup < somefile.html > prettyfile.html

Within VIM (manually)

You don't have to write the file back to disk if you don't want to, but I included the step that would get the identical effect as the commandline example.

$ vi somefile.html
:!python -m BeautifulSoup < %
:w prettyfile.html

Within VIM (define key-mapping)

In ~/.vimrc define:

nmap =h !python -m BeautifulSoup < %<CR>

Then, when you open a file in vim and it needs beautification

$vi somefile.html
=h
:w prettyfile.html

Once again, saving the beautification is optional.

Python Shell

$ python
>>> from BeautifulSoup import BeautifulSoup as parse_html_string
>>> from os import path
>>> uglyfile = path.abspath('somefile.html')
>>> path.isfile(uglyfile)
True
>>> prettyfile = path.abspath(path.join('.', 'prettyfile.html'))
>>> path.exists(prettyfile)
>>> doc = None
>>> with open(uglyfile, 'r') as infile, open(prettyfile, 'w') as outfile:
...     # Assuming very simple case
...     htmldocstr = infile.read()
...     doc = parse_html_string(htmldocstr)
...     outfile.write(doc.prettify())

# That's it; you can manually manipulate the dom too though
>>> scripts = doc.findAll('script')
>>> meta = doc.findAll('meta')
>>> print doc.prettify()
[imagine beautiful html here]

>>> import jsbeautifier
>>> print jsbeautifier.beautify(script.string)
[imagine beautiful script here]
>>> 

---

BeautifulSoup has a function called prettify which does this. See this question

---

There's also the html5print module. Key features from the description page:

• Pretty print HTML as well as embedded CSS and JavaScript within it
• Pretty print pure CSS and JavaScript
• Try to fix fragmented HTML5
• Try to fix HTML with broken unicode encoding
• Try to guess encoding of the document, and in some cases manage to convert 8-bit byte code back into correct UTF-8 format
• Support both Python 2 and 3

---

Here's my pure python solution:

from xml.dom.minidom import parseString as string_to_dom

def prettify(string, html=True):
    dom = string_to_dom(string)
    ugly = dom.toprettyxml(indent="  ")
    split = list(filter(lambda x: len(x.strip()), ugly.split('\n')))
    if html:
        split = split[1:]
    pretty = '\n'.join(split)
    return pretty

def pretty_print(html):
    print(prettify(html))

When used on your block of html:

html = """<ul><li>Item</li><li>Item</li></ul>"""
pretty_print(html)

I get:

<ul>
  <li>Item</li>
  <li>Item</li>
</ul>