Vim as XML Editor: More Tasks

If you just want to check for well-formedness, enter

:!xmllint --noout %

Most often you will want to validate the document. The following command writes the buffer to xmllint:

:%w !xmllint --valid --noout -

This means you can validate the document with all changes, without having to save it first. If you set up a shell script or batch file just for validation, eg then you can simply do

:%w !xmllintval -

If you want to validate the file, pass the file's path to the validator:

:!xmllint --valid --noout %

or

:!xmllintval %

xmllint also allows you to validate documents which don't have a document type declaration . Let's say you have a DBX chapter file

<?xml version="1.0" encoding="UTF-8"?>
<chapter>
  <title>Setup</title>
...

which is included in the main book file via an entity reference

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book
  PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "https://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[
 <!ENTITY setup SYSTEM "setup.dbx">
 ...
]>
...
&setup;
...

This means the chapter file can't have a doctype declaration. XInclude is a solution for that problem but it's not yet as widely supported as the entity reference mechanism which is part of the XML standard itself. Being able to validate documents which have no document type declaration is generally useful, and factors like the growing popularity of RNG, namespaces and version/profile attributes, and the hopefully decreasing dependence on DTDs to modify the document's information set will probably mean that less documents will have document type declarations. So let's say you edit the chapter in Vim and want to validate the buffer.

:%w !xmllint --valid --noout -

will fail because there is no FPI included and no DTD referenced. So you can try the following (one line):

:%w !xmllint --dtdvalid
 "https://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" --noout -

If you set up the catalog as described in the previous chapter then this works offline. (It won't work if the chapter contains references to entities that are declared in the main (book) file. In this case you probably would feed the main file to the validator.) The line doesn't have to be changed when used on a different machine which means that you can add it to your crossplatform vimrc:

nmap <Leader>d4 :%w !xmllint --dtdvalid 
 \ "https://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
 \ --noout -<CR>

Alternatively you can pass the FPI to xmllint (one line)

:%w !xmllint --dtdvalidfpi
 "-//OASIS//DTD DocBook XML V4.2//EN" --noout -

if it's listed in a catalog. [mapleader] d 4 works great for DBX chapters which are external entities referenced from the main book file as long as the following requirements are met: In addition to being an external parsed entity (can't contain a doctype declaration) the file must also be an XML document. In other words: Since the file can't contain entity declarations it also can't contain entity references. Making sure that modules of a DBX document are well-formed XML documents that can stand alone is generally a good idea since it simplifies collaboration and exchange, reuse, and last but not least editing and validation.

To validate the buffer with RXP, type

:%w !rxp -V -N -s -x

If you have set up rxpval you can enter

:%w !rxpval

This will not work if there are relative references to external entities and the current directory is not that of the file being validated (this also goes for stuff like :%w !xmllintval -). When RXP or xmllint eat stdin they use the current directory as base directory when resolving relative references. So if you want to validate a buffer which has relative references to external entities, you can do

:cd /directory/of/the/file/

to change the working directory, and

:pwd

to check it. A more convenient way to change the working directory is to put

map <Leader>cd :exe 'cd ' . expand ("%:p:h")<CR>

into your vimrc then do [mapleader] c d before writing the buffer to the validator via :%w !command....

If you want to validate the file, then it's not necessary to change the working directory. You can simply pass the file path, eg

:!rxp -V -N -s -x %

or

:!rxpval %

RXP works with XHTML documents, but with DBX documents I experienced problems which hopefully will be resolved with future releases. There are various command line options; check the RXP man page.

The commands are long enough to be tedious to type each time. After you've entered a specific one once, you can look for it in the command history:

• Type : to go to Vim's command line,
• optionally type the start of the command,
• then repeat [up] until you see the command you were looking for.

Now you can edit it, or enter it unmodified. Another way of saving typing is to map commands to a very short key sequence in the vimrc.

Select a well-formed fragment (one root element), then filter it through xmllint's pretty-printer, by entering

!xmllint --format -

xmllint will insert an XML prolog; if you didn't filter the whole buffer, this probably isn't desired. You can map this filter command to some shorter key sequence, and also include some commands to delete the prolog. To pretty-print the whole buffer, do

:%!xmllint --format -

<?xml version="1.0"?>
<chapter><title>Ökopläne</title><simplelist>
<member role="überfällig">übermäßige
Ölförderung stoppen</member></simplelist></chapter>

:%!xmllint --format --encode UTF-8 -

<?xml version="1.0" encoding="UTF-8"?>
<chapter>
  <title>Ökopläne</title>
  <simplelist>
    <member role="&#xFC;berf&#xE4;llig">übermäßige
Ölförderung stoppen</member>
  </simplelist>
</chapter>

To delete all comments do

:%!xmlstar ed -d //comment()

:%!tidy

!}tidy

:%s,</\?u>,,g