Reimplement the serializer as an explicit work-stack walk instead of recursion,
mirroring libxml2's xmlNodeDumpOutputInternal, so it is no longer the depth
bottleneck. Reimplemented in Swift; no upstream code copied.
Also fix a mixed-content correctness bug: formatting is now suppressed for any
element with text or CDATA children (previously only when ALL children were
text), so pretty-printing never injects whitespace around significant text.
Note surfaced while testing: the remaining depth ceiling is the recursive
Model.Node indirect enum (recursive ARC teardown overflows at extreme depth),
which is why the parser must cap nesting depth (next).
The serializer escaped only & < " in attribute values, so an attribute holding
tab, newline, or carriage return would not survive a spec-compliant parser's
attribute-value normalization. Match the libxml2 attribute escape table: emit
	 for the whitespace characters and > for >. Behavior derived
from the libxml2 analysis (xmlsave.c / xmlIO.c escape tables), reimplemented in
Swift; no upstream code copied.
Replace the notImplemented stub with a real parser built on a pull-based,
streaming event core that never requires the whole document in memory.
- Parsing.EventReader: pulls characters through a source closure with a bounded
lookahead buffer and emits one Parsing.Event at a time, holding only an
open-element stack. Drives chunked/streamed input.
- Parsing.Parser: builds a Model.Node tree iteratively over the event core
(explicit stack, no recursion).
- Reader: streaming character cursor (closure-backed, bounded buffer) replacing
the previous whole-string Array.
- EntityDecoder: the five predefined entities and decimal/hex char references.
- Handles elements, attributes, text, comments, CDATA, processing instructions,
and an XML declaration in the prolog. Rejects <!DOCTYPE> by default (no
DTD/XXE/entity-expansion exposure).
- Top-level API: parse(_:), parse(pulling:), events(_:), events(pulling:).
- 21 tests including event-stream and chunked-source coverage.
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
