Validation errors should include the containing (parent) element context

[chrispitude]

Currently, validation errors show the expected element within the current element, but not the identity of the containing element itself, forcing the user to open a text editor to determine where 'here' is based on line number and column:

test.xml:6:11: error: element "BOTTOM" not allowed here; expected the element end-tag

It would be great if the error message could include the identity of the containing element too (see 'here'):

test.xml:6:11: error: element "BOTTOM" not allowed in "TOP" here; expected the element end-tag

Our specific use case is DITA validation via the DITA-OT, but this enhancement would be widely useful.

[chrispitude]

Grammar file:

<?xml version="1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="TOP">
      <element name="MID">
        <element name="BOTTOM"><text/></element>
      </element>
    </element>
  </start>
</grammar>

Test XML file:

<?xml version="1.0"?>
<TOP>
  <MID>
    <BOTTOM>this is okay</BOTTOM>
  </MID>
  <BOTTOM>oops, not allowed here</BOTTOM>
</TOP>

[chrispitude]

I believe this enhancement would be in

https://github.com/relaxng/jing-trang/blob/master/mod/pattern/src/main/com/thaiopensource/relaxng/pattern/PatternMatcher.java

in the following statement:

      if (!ok)
        error(next.isNotAllowed() ? "unknown_element" : "out_of_context_element",
              errorArgQName(qName, name, context, false),
              expectedContent(context));
}

but I don’t know Java and I have no idea how to get access to the parent of the current element to pass that as an additional name argument. :(

[chrispy-snps]

Bump - does anyone know how this could be implemented?