Add PureXML.XPath: a compiled location-path query engine reimplemented from the
XPath 1.0 specification; no upstream code copied.
- Compiler parses a path into steps; Evaluator walks the tree returning a
Selection node-set (node or attribute) in document order.
- Forward axes only (child, descendant //, self ., attribute @), since the value
model has no parent pointers. Node tests: name, *, text(), node(), comment().
Predicates: [n], [@a], [@a='v'], [child], [child='v'].
- Public surface: XPath.Query (init compiles, evaluate/elements/strings), the
Selection enum (element / stringValue), QueryError, and the one-shot
PureXML.xpath(_:over:). Upward/sibling axes and the full expression language
are explicitly out of scope.
- 12 XPath tests; 61 total.
Root Swift package mirroring PureYAML's structure, rules, and verification
gates. Includes the XML node model (Node, Element, Attribute, QualifiedName),
a working emitter (Serializer) with escaping and pretty/compact options, and
structural validation. The parser surface is stable; parse() raises
notImplemented until the scanner lands, pinned by a test.
- dependency-free, namespaced under PureXML
- portability and style gates carried over (style, namespacing, forbidden
patterns, swiftformat, swiftlint, linux, wasm, windows CI)
- 11 tests passing
