convert xhtml back to html

[Tim Arnold]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop to
create CHM files. That application really hates xhtml, so I need to convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to do
that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work. I'm not
enough of a regexp pro to figure out that lookahead stuff.

I'm not sure where to start now; I looked at BeautifulSoup and
BeautifulStoneSoup, but I can't see how to modify the actual tag.

thanks,
--Tim Arnold

 

[Gary Herron]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop to
create CHM files. That application really hates xhtml, so I need to convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to do
that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work. I'm not
enough of a regexp pro to figure out that lookahead stuff.

I'm not sure where to start now; I looked at BeautifulSoup and
BeautifulStoneSoup, but I can't see how to modify the actual tag.

thanks,
--Tim Arnold

Whether or not you can find an application that does what you want, I
don't know, but at the very least I can say this much.

You should not be reading and parsing the text yourself! XHTML is valid
XML, and there a lots of ways to read and parse XML with Python.
(ElementTree is what I use, but other choices exist.) Once you use an
existing package to read your files into an internal tree structure
representation, it should be a relatively easy job to traverse the tree
to emit the tags and text you want.


Gary Herron

 

[Arnaud Delobelle]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop to
create CHM files. That application really hates xhtml, so I need to convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to do
that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work. I'm not
enough of a regexp pro to figure out that lookahead stuff.

Hi, I'm not sure if this is very helpful but the following works on
the very simple example below.

import re
xhtml = '<p>hello <img src="/img.png"/> spam <br/> bye </p>'
xtag = re.compile(r'<([^>]*?)/>')
xtag.sub(r'<\1>', xhtml)

'<p>hello <img src="/img.png"> spam <br> bye </p>'

 

[Walter Dörwald]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop to
create CHM files. That application really hates xhtml, so I need to convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to do
that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work. I'm not
enough of a regexp pro to figure out that lookahead stuff.

Hi, I'm not sure if this is very helpful but the following works on
the very simple example below.

import re
xhtml = '<p>hello <img src="/img.png"/> spam <br/> bye </p>'
xtag = re.compile(r'<([^>]*?)/>')
xtag.sub(r'<\1>', xhtml)

'<p>hello <img src="/img.png"> spam <br> bye </p>'

You might try XIST (http://www.livinglogic.de/Python/xist):

Code looks like this:

from ll.xist import parsers
from ll.xist.ns import html

xhtml = '<p>hello <img src="/img.png"/> spam <br/> bye </p>'

doc = parsers.parsestring(xhtml)
print doc.bytes(xhtml=0)

This outputs:

<p>hello <img src="/img.png"> spam <br> bye </p>

(and a warning that the alt attribute is missing in the img )

Servus,
Walter

 

[Tim Arnold]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop
to create CHM files. That application really hates xhtml, so I need to
convert self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to
do that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work.
I'm not enough of a regexp pro to figure out that lookahead stuff.

I'm not sure where to start now; I looked at BeautifulSoup and
BeautifulStoneSoup, but I can't see how to modify the actual tag.

thanks,
--Tim Arnold

Whether or not you can find an application that does what you want, I
don't know, but at the very least I can say this much.

You should not be reading and parsing the text yourself! XHTML is valid
XML, and there a lots of ways to read and parse XML with Python.
(ElementTree is what I use, but other choices exist.) Once you use an
existing package to read your files into an internal tree structure
representation, it should be a relatively easy job to traverse the tree to
emit the tags and text you want.


Gary Herron

I agree and I'd really rather not parse it myself. However, ET will clean up
the file which in my case includes some comments required as metadata, so
that won't work. Oh, I could get ET to read it and write a new parser--I see
what you mean. I think I need to subclass so I could get ET to honor those
comments too.
That's one way to go, I was just hoping for something easier.
thanks,
--Tim

 

[Tim Arnold]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop
to
create CHM files. That application really hates xhtml, so I need to
convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

Seems simple enough, but I'm having some trouble with it. regexps trip up
because I also have to take into account 'img', 'meta', 'link' tags, not
just the simple 'br' and 'hr' tags. Well, maybe there's a simple way to
do
that with regexps, but my simpleminded <img[^(/>)]+/> doesn't work. I'm
not
enough of a regexp pro to figure out that lookahead stuff.

Hi, I'm not sure if this is very helpful but the following works on
the very simple example below.

import re
xhtml = '<p>hello <img src="/img.png"/> spam <br/> bye </p>'
xtag = re.compile(r'<([^>]*?)/>')
xtag.sub(r'<\1>', xhtml)

'<p>hello <img src="/img.png"> spam <br> bye </p>'

Thanks for that. It is helpful--I guess I had a brain malfunction. Your
example will work for me I'm pretty sure, except in some cases where the IMG
alt text contains a gt sign. I'm not sure that's even possible, so maybe
this will do the job.
thanks,
--Tim

 

[bryan rasmussen]

I'll second the recommendation to use xsl-t, set the output to html.


The code for an XSL-T to do it would be basically:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xslutput method="html" />
<xsl:template match="/"><xsl:copy-of select="/"/></xsl:template>
</xsl:stylesheet>

you would probably want to do other stuff than just copy it out but
that's another case.

Also, from my recollection the solution in CHM to make XHTML br
elements behave correctly was <br /> as opposed to <br/>, at any rate
I've done projects generating CHM and my output markup was well formed
XML at all occasions.

Cheers,
Bryan Rasmussen

 

[Stefan Behnel]

hi, I've got lots of xhtml pages that need to be fed to MS HTML Workshop to
create CHM files. That application really hates xhtml, so I need to convert
self-ending tags (e.g. <br />) to plain html (e.g. <br>).

This should do the job in lxml 2.x:

from lxml import etree

tree = etree.parse("thefile.xhtml")
tree.write("thefile.html", method="html")

http://codespeak.net/lxml

Stefan

 

[bryan rasmussen]

wow, that's pretty nice there.

Just to know: what's the performance like on XML instances of 1 GB?

Cheers,
Bryan Rasmussen

 

[Stefan Behnel]

bryan rasmussen top-posted:

wow, that's pretty nice there.

Just to know: what's the performance like on XML instances of 1 GB?

That's a pretty big file, although you didn't mention what kind of XML
language you want to handle and what you want to do with it.

lxml is pretty conservative in terms of memory:

http://blog.ianbicking.org/2008/03/30/python-html-parser-performance/

But the exact numbers depend on your data. lxml holds the XML tree in memory,
which is a lot bigger than the serialised data. So, for example, if you have
2GB of RAM and want to parse a serialised 1GB XML file full of little
one-element integers into an in-memory tree, get prepared for lunch. With a
lot of long text string content instead, it might still fit.

However, lxml also has a couple of step-by-step and stream parsing APIs:

http://codespeak.net/lxml/parsing.html#the-target-parser-interface
http://codespeak.net/lxml/parsing.html#the-feed-parser-interface
http://codespeak.net/lxml/parsing.html#iterparse-and-iterwalk

They might do what you want.

Stefan

 

[Jim Washington]

bryan rasmussen top-posted:


That's a pretty big file, although you didn't mention what kind of XML
language you want to handle and what you want to do with it.

lxml is pretty conservative in terms of memory:

http://blog.ianbicking.org/2008/03/30/python-html-parser-performance/

But the exact numbers depend on your data. lxml holds the XML tree in memory,
which is a lot bigger than the serialised data. So, for example, if you have
2GB of RAM and want to parse a serialised 1GB XML file full of little
one-element integers into an in-memory tree, get prepared for lunch. With a
lot of long text string content instead, it might still fit.

However, lxml also has a couple of step-by-step and stream parsing APIs:

http://codespeak.net/lxml/parsing.html#the-target-parser-interface
http://codespeak.net/lxml/parsing.html#the-feed-parser-interface
http://codespeak.net/lxml/parsing.html#iterparse-and-iterwalk

If you are operating with huge XML files (say, larger than available
RAM) repeatedly, an XML database may also be a good option.

My current favorite in this realm is Sedna (free, Apache 2.0 license).
Among other features, it has facilities for indexing within documents
and collections (faster queries) and transactional sub-document updates
(safely modify parts of a document without rewriting the entire
document). I have been working on a python interface to it recently
(zif.sedna, in pypi).

Regarding RAM consumption, a Sedna database uses approximately 100 MB of
RAM by default, and that does not change much, no matter how much (or
how little) data is actually stored.

For a quick idea of Sedna's capabilities, the Sedna folks have put up an
on-line demo serving and xquerying an extract from Wikipedia (in the
range of 20 GB of data) using a Sedna server, at
http://wikidb.dyndns.org/ . Along with the on-line demo, they provide
instructions for deploying the technology locally.

- Jim Washington

 

[Tim Arnold]

I'll second the recommendation to use xsl-t, set the output to html.


The code for an XSL-T to do it would be basically:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xslutput method="html" />
<xsl:template match="/"><xsl:copy-of select="/"/></xsl:template>
</xsl:stylesheet>

you would probably want to do other stuff than just copy it out but
that's another case.

Also, from my recollection the solution in CHM to make XHTML br
elements behave correctly was <br /> as opposed to <br/>, at any rate
I've done projects generating CHM and my output markup was well formed
XML at all occasions.

Cheers,
Bryan Rasmussen

Thanks Bryan, Walter, John, Marc, and Stefan. I finally went with the xslt
transform which works very well and is simple. regexps would work, but they
just scare me somehow. Brian, my tags were formatted as <br /> but the help
compiler would issue warnings on each one resulting in log files with
thousands of warnings. It did finish the compile though, but it made
understanding the logs too painful.

Stefan, I *really* look forward to being able to use lxml when I move to RH
linux next month. I've been using hp10.20 and never could get the requisite
libraries to compile. Once I make that move, maybe I won't have as many
markup related questions here!

thanks again to all for the great suggestions.
--Tim Arnold