Add code action to generate RelaxNG grammar

[JessicaJHee]

Fixes #1405

Signed-off-by: Jessica He jhe@redhat.com

[JessicaJHee]

Currently I have the start of the generated file as:

<?xml version="1.0" encoding="UTF-8"?>
<element name="rootElementName" xmlns="http://relaxng.org/ns/structure/1.0">
...

I see in other examples they have something like :

<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0" 
         xmlns:sch="http://purl.oclc.org/dsdl/schematron"
         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
    <start>
        <element name="rootElementName">
        ...

I wonder if the second case is better/more accepted?

[angelozerr]

It looks promising !

I think you should generate grammar element because

• the most rng file that I have seen uses grammar
• we have a snippet in rng file which generates grammar. To be consistent with this snippet I think it is better to generate grammar element

In your demo you generate an rng prefix. I think yuu should generate without prefix. Please see the rng snippet

[angelozerr]

Please generate the same content than snippet https://github.com/eclipse/lemminx/blob/main/org.eclipse.lemminx/src/main/resources/org/eclipse/lemminx/services/snippets/new-rng-snippets.json

• without rng prefix
• with grammar element
• with datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes"
• with define pattern

[angelozerr]

The PR looks very good. If CI build works I m OK to merge the PR.

We will improve it and fix bugs on another PR