I have been wondering whether it would be possible to use xslt to render .leo files from web pages. This would build on Ville's work. First, a demo:
1. Copy the two attached files to the same folder on your hard drive.
Note: recent revs have added these two files to the top-level leo folder,
so you could also use those files instead. Both demo files are now in the
top-level leo-editor in the git repo *and* on leoeditor.com.
2. Open xslt-test.leo in your browser. You should see something like this:
test.leo
-
This is a test
node 1
-
Node 1 text.
node 2
-
Node 2 text.
That is, browsers (tested with IE and Mozilla) can render .leo files on
your file system as html.
Alas, there are problems rending .leo files from urls instead of files. But
when we succeed we will have a read-only version of Leo as a web app!
===== About leo_to_html.xsl
Ville created leo_to_html.xsl, but I didn't understand its significance
until early this morning. This xslt file tells a web browser (or other
xslt processor) how to render a .leo file as html.
I made several changes this morning to leo_to_html.xsl so that it works
with the "tryit" editor for xslt at w3schools:
http://www.w3schools.com/xsl/tryxslt.asp?xmlfile=cdcatalog&xsltfile=cdcatalog_ex1
This editor is a good way to discover problems either in .xsl files
themselves or references to .xsl files from .xml files.
===== Problems
It does not seem possible to use leo_to_html.xsl directly:
1. Visiting http://leoeditor.com/xslt-test.leo does not work.
The browser renders xslt-test.leo xml, not html. That is, the browser does
not perform the xslt transformations.
2. Visiting
https://github.com/leo-editor/leo-editor/blob/master/xslt-test.leo shows
the "raw" xml, without the xslt transformations being applied.
The reason is clear enough. The url is a *representation* of the .leo file,
not the .leo file itself.
3. xslt-test.leo contains the following line::
<?xml-stylesheet type="text/xsl" href="leo_to_html.xsl"?>
This line is supposed to be set by the following setting::
@string stylesheet = ekr_test
This default is useless, and setting it to::
@string stylesheet = type="text/xsl" href="leo_to_html.xsl"
does not appear to work. I'll look into this, but cutting and pasting the
desired <?xml-stylesheet > element into .leo files should work well enough
for testing.
4. By default, Mozilla refuses to render xslt-test.leo containing the
following stylesheet element::
<?xml-stylesheet type="text/xsl" href="leoeditor.com/leo_to_html.xsl"?>
In other words, Mozilla refuses to execute "remote" .xsl files. A cryptic
message is shown instead. Googling that message gives:
http://stackoverflow.com/questions/3420513/firefox-and-remote-xsl-stylesheets
Apparently Mozilla enforces "same origin" policy. But it's no good
relaxing that policy: browsers on smart phones are probably even more
restrictive.
===== Conclusions
The tryit editor shows that it is possible to apply arbitrary xslt style
sheets to arbitrary xml files. We should be able to create a page, say on
leoeditor.com, that would render .leo files properly using
leo_to_html.xsl. The question is, how exactly to do this?
This is exciting, despite the problem listed above, and probably others.
The xslt approach is almost infinitely easier than alternative approaches.
Once we can properly render, say, a link to a .leo file on GitHub, we can
start improving leo_to_html.xsl. The obvious thing to do is to change the
xsl so that it generates html similar to that generated by Bernhard
Mulder's mod_http plugin.
Your comments, please.
Edward
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leo_to_html.xsl
Description: XML document
xslt-test.leo
Description: Binary data
