Fix XPath self axis nodeset position

[tompng]

Self axis should create nodesets that each node have position=1

Nokogiri::XML('<a><b/><c/><d/></a>').xpath('a/*/self::*[1]').map(&:name)
# => ["b", "c", "d"]

REXML::XPath.match(REXML::Document.new('<a><b/><c/><d/></a>'),'a/*/self::*[1]')
#=> [<b/>] (master, rexml-3.4.4)
#=> [<b/>, <c/>, <d/>] (this PR)

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR fixes XPath self axis predicate evaluation so positional predicates (e.g., [1], [2]) are applied per node rather than across the entire nodeset, and adds a regression test to validate the corrected behavior.

Changes:

• Update :self axis evaluation to iterate over singleton nodesets per node, ensuring correct predicate context/positioning.
• Add a test confirming self::*[1] matches each node’s own “self” and self::*[2] matches none in that pattern.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
test/xpath/test_base.rb	Adds regression coverage for self axis positional predicate behavior.
lib/rexml/xpath_parser.rb	Adjusts :self axis nodeset iteration to apply predicates with the correct per-node context.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[naitoh]

Thank you!