XML Rules in 7.0.0

[justinstroudbah]

Hi all,

While working on the Salesforce metadata module, I'm building some java rules in order to validate the approach (and add some basic rules to the module.) However, there is no ASTVisitor in the 7.0 XML namespace and the only visit(...) method that was in 6.55's AbstractXmlRule class was deprecated.

Since AbstractXmlRule inherits from Rule, it requires apply(AstVisitor,Object) so that leaves me in a bind.

• Is there another alternative to the previous void visit(...) method that was in 6.55
• Is there a new method of visiting XML nodes that doesn't involve an explicit, language-specific visitor?
• Am I crazy? :)

Thanks!

[adangel]

Hi @justinstroudbah ,

there is indeed no visitor or something like that. So far, we only have written XPath based rules, we didn't have a need yet to write Java rule.

But the entry point for Java-based rules is:

• Subclass net.sourceforge.pmd.lang.xml.rule.AbstractXmlRule
• override the method void apply(Node target, RuleContext ctx)
• this gives you the root node of the XML document. You can assume at this point, that it is a net.sourceforge.pmd.lang.xml.ast.XmlNode.
• from there, you can use the NodeStream API to query the "AST".

We probably didn't write a visitor, because there are not really different node types - there is only one possible node type, and that is XmlNode... so, we would have a visitor with a single visit method... Of course, you now need to traverse the tree yourself (using children(), descendants(), ancestors(), etc.)

If a visitor is really needed, we can of course add it. The visit method would then visit all nodes...

[justinstroudbah]

Thanks for that. I wanted to make sure I wasn't missing something somewhere. That makes sense. So the pseudocode for that would be:

@override
public void apply(Node target, RuleContext ctx) {
    // Traverse the nodes, perform checks, etc. Any violations would be reported
    // in the same manner as they were before:
    asCtx(data).addViolation(node);
}

Correct? This would also work with multiple rules, as each rule would have its own apply(...) right?

[adangel]

Yes, each rule has a separate apply(...) method.
Note: you don't need this "asCtx", as we have here already the RuleContext. So you can simply write ctx.addViolation(node).