XML v0.5 (WIP) — FlatNode, node identity, LazyNode XPath#85
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The fourth reader alongside Node/LazyNode/Cursor: parse(xml, FlatNode) materializes the whole document once into a contiguous store of isbits records (parent/first_child/next_sibling index links, zero-copy byte ranges into the retained source), so building is fast, random access is O(1), and the GC traces a handful of arrays instead of one object per node. Text and attribute values are entity-decoded at access (the has_entities token flag rides the sign bit of the stored length). The builder is the same single visibly-pushdown pass as _parse with the same well-formedness checks at the same token points (shared check functions; identical error messages, asserted by the parity tests). FlatNode == / hash are positional identity — same store, same node (the #83 semantics, debuting on the new reader). Node(flatnode) materializes a subtree as a mutable Node; XML.write accepts FlatNode. O(1) parent and O(depth) 1-arg depth come free from the stored links. Assisted-by: Claude (Anthropic)
The new W3C parity testset asserts FlatNode ≡ Node (decoded trees) on every well-formed document of the pinned conformance suite, and the exact same accept/reject verdict on every not-well-formed one — any divergence between the flat builder and _parse is a named failure. It caught exactly one on first run, on 5 documents (sun/invalid/empty.xml, oasis p15pass1/p18pass1, ibm P15/P20): an empty comment <!----> or CDATA <![CDATA[]]> has value "" on Node but came back nothing on FlatNode, because the record encoded absence as len == 0. Absence is now value_offset == -1 (empty content keeps a real offset with len 0), matching the Node parser on all three states: absent, empty, present. Assisted-by: Claude (Anthropic)
Assisted-by: Claude (Anthropic)
Add FlatNode: read-only columnar full-DOM reader (#82)
benchmarks/flatnode_bench.jl measures build/walk/extract/retained/GC against Node, Cursor and EzXML (min-of-5, XMark). Findings recorded: FlatNode wins build 1.8x, structural walk 1.7x, retained 1.7x, and end-to-end extraction 1.65x; pure accessor loops over an already-built tree remain ~1.8x slower than Node's direct field reads (SubString construction + boundary walks) — the one regime where the mutable DOM is faster, documented rather than chased into unsafe string internals. Assisted-by: Claude (Anthropic)
A parallel spans column in the store (SoA style — no record churn, +8 B/node) tracks each node's exact raw source slice, set from the opening marker token and patched at the closing one (the CLOSE_TAG token covers only '</name'; the closing '>' — ETag allows 'S? >' — is located with findnext). sourcetext(::FlatNode) returns the zero-copy slice, asserted equal to LazyNode's sourcetext, and unblocks consumers that keep raw entry slices (e.g. XLSX's shared-string table loader). Assisted-by: Claude (Anthropic)
Needed by consumers that probe <t>-style leaves (e.g. XLSX's shared string loader); asserted against Node in the accessor parity tests. Assisted-by: Claude (Anthropic)
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #85 +/- ##
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+ Coverage 94.47% 94.94% +0.46%
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Files 11 12 +1
Lines 1793 2057 +264
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+ Hits 1694 1953 +259
- Misses 99 104 +5
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Long-lived integration PR for XML v0.5 — mirrors the role #76 played for v0.4: every push to
v0.5-devgets the full CI matrix + the XLSX Downstream check, and this PR is the eventual merge vehicle for the release.Landed so far:
FlatNode— read-only columnar full-DOM reader (FlatNode: read-only columnar full-DOM reader (planned for v0.5) #82, merged via Add FlatNode: read-only columnar full-DOM reader (#82) #84): W3C parity with theNodeparser (decoded-equivalent trees on all 776 valid documents, identical verdicts on all 1257 not-wf), positional==/hash(Node identity: === and hash redesign (planned for v0.5) #83 semantics), O(1)parent,Node(::FlatNode)bridge,XML.writesupport.sourcetext(::FlatNode)(SoA side column, zero-copy, asserted equal toLazyNode's),is_simple_value,@inlineaccessors, and a by-regime benchmark script (benchmarks/flatnode_bench.jl).Backlog before release:
===/hashredesign onNode(#83, #55),LazyNodeXPath (#79).