This is a fork of hubgit/xml.js, which is a fork of kripken/xml.js.

In this particular fork, work has been done to adapt libxml2 to the specific needs of the JATS4R validator, which is a client-side validation tool.

This package exports the xmltool program, which can do one of two things:

• Under normal circumstances, it acts exactly the same as libxml2's xmllint command;
• If the first argument is --xpath-locator, then this performs a specialized task of determining the exact file locations of a set of XPath expressions.

var args = ['--noent', '--dtdvalid', dtdPath, xmlPath];
var files = [
  {
    path: dtdPath,
    data: dtdContents
  },
  {
    path: xmlPath,
    data: xmlContents
  }
];
var ret = xmltool(args, files);

args is an array of arguments to pass to the program.

files is an array of objects, each with a path and data property. These will be turned into pseudo-filesystem objects for the program to access.

The return value object has two properties: 'stdout' and 'stderr'. For example:

if (!ret.stderr) {
  // there were no errors.
}

This is a tool to take the XPath expressions produced by the Schematron output, and locate them within the XML documents, by column and line number.

Invoke it with:

var args = ['--xpath-locator', xmlPath, xpath1, xpath2];
var files = [{
  path: xmlPath,
  data: xmlContents
}];
var ret = xmltool(args, files);
if (!ret.stderr) {
  // no errors
}

The output will be a set of line and column numbers, one per line. The line and the column number separated by a colon. For example, if there were three XPath expressions, then the output might look like this:

30:34
44:19
28:12

The XPath expressions are restricted to a very rigid form; the form that is produced by the Schematron validation output. They are used to identify a specific element in the document tree. Here are some examples:

/article[1]/body[1]/p[2]/*:math[namespace-uri()='http://www.w3.org/1998/Math/MathML'][1]
/article[1]/body[1]/sec[2]/p[2]

The validator will continue to use xmllint in the first pass, to do DTD validation and entity resolution.

Both xmllint and xpath-locator use the libxml2 library. However, both need to be called as main programs. So, to avoid redundantly including all of the libxml2 code in two separate JavaScript libraries, we created one main module, in xmltool.c, that delegates to either xmllint.c or to xpath_locator.c, depending on the first command-line option.

To allow xmllint to be called as a subroutine to something else. Rather than hack the libxml2 version of xmllint, we copied it out of libxml2, and changed it in the copy.

The output of all this is a JavaScript library, xmltool.js, which works as follows:

• If the very first command line argument is --xpath-locator, then it is stripped out, and the xpath_locator function is called with the rest of the arguments
• Otherwise, xmllint is called.

Install the Emscripten SDK. When that's done, make sure that you source the emsdk_env.sh script, to set up your environment to use it.

git clone --recursive https://github.com/JATS4R/xml.js.git
cd xml.js

npm install
npm install -g gulp

gulp clean
gulp libxml2
gulp compile
gulp test     # currently failing with "./test/test.xml fails to validate"

To test in a browser, make sure your repo is being served by an HTTP server, and open up the following files in a browser:

• test/test-xmllint.html - verify that:
  • The file validates ("Valid!" should appear after a short delay)
  • In the first <journal-id>, the name should appear as "你好PeerJ" -- this tests that UTF-8 output serialization works correctly
• test/test-xpath-locator.html

Here are the steps to compile xpath_locator as a stand-alone binary executable.

It might or might not be necessary to first download, build, and install a working copy of libxml2. For example, download the hourly snapshot from here, for example, ftp://xmlsoft.org/libxml2/libxml2-git-snapshot.tar.gz. Cloning the git repo would require extra steps, because it doesn't include a configure script. Unzip it, and cd into the directory. Decide where you want to install it, e.g. "/home/user/libxml2/install", and then:

./configure --prefix=/home/user/libxml2/install
make
make install

To set your environment to use this, add the install/bin directory to the front of your PATH. Then, confirm with which xml2-config.

Next, change to the src project directory, and build xpath_locator as a stand-alone program, with:

gcc -DXPATH_LOCATOR_MAIN `xml2-config --cflags --libs` -o xpath_locator xpath_locator.c

Test with the following. The first four should find a match, the fifth, not.

./xpath_locator ../test/test-xpath-locator.xml \
  '/article[1]/front[1]/article-meta[1]/permissions[1]/copyright-你好[1]' \
  '/article[1]/body[1]/p[2]/*:math[namespace-uri()='"'"'http://www.w3.org/1998/Math/MathML'"'"'][1]' \
  '/article[1]/body[1]/sec[2]/p[2]' \
  '/article[1]/body[1]/p[1]/sub[1]' \
  '/article[1]/body[1]/p[1]/sub[1]/em[1]'