Add in template attribute definitions in the desc.xml

[kaby76]

See https://github.com/antlr/grammars-v4/pull/4020.

[kaby76]

My thinking is to have attributes defined in a list of elements.

• Replace transformGrammar.py with template attributes in desc.xml. The main problem is that transformGrammar.py only works on a file, not the whole set of template files.

  <?xml version="1.0" encoding="UTF-8" ?>
  <desc xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../_scripts/desc.xsd">
  <target>
      <name>Cpp</name>
      <files>*.g4</files>
      <modifiers>
          <attr>this.</attr>
          <repl>this->.</repl>
      </modifiers>
  </target>
  </desc>

  Here, an "attribute" can just be a pattern that is replaced.

• Pure attribute.

  <?xml version="1.0" encoding="UTF-8" ?>
  <desc xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../_scripts/desc.xsd">
  <target>
     <name>Java</name>
     <modifiers>
        <attr>package</attr>
        <repl>org.antlr4.python</repl>
     </modifiers>
  </target>
  </desc>