[feature] Support map atomization in XQuery 4.0

[joewiz]

Summary

• Add version-gated map atomization for XQuery 4.0 (maps are atomizable in XQ4 but not in XQ 3.1)
• Resolves ~103 XQTS QT4 test failures caused by err:FOTY0013 when atomizing map results
• XQ 3.1 behavior unchanged: maps still raise FOTY0013

What Changed

AbstractMapType.java

• isXq4Atomizable() — version gate: returns true when context.getXQueryVersion() >= 40
• atomizeValues() — iterates all map entries, atomizes each value, returns flat Sequence
• atomize() override — for XQ4 single-entry maps returns the atomized value; for XQ 3.1 throws FOTY0013

Atomize.java

• Updated static atomize(Sequence) to detect XQ4 maps and expand them via atomizeValues() before individual item atomization — same pattern as ArrayType.flatten() for arrays

ConcatExpr.java

• The FOTY0013 guard for function items now has a carve-out: XQ4 maps are atomized and their string values concatenated

Spec References

• XQuery 4.0 Data Model — Maps: Maps are no longer function items; they have a typed value (the concatenation of the typed values of their entries' values)
• XQuery 3.1 — FOTY0013: Raised when atomizing a function item other than an array

Test Plan

• Build compiles on develop (no XQ4 parser = dormant code path, safe to merge independently)
• XQSuite tests (1218): zero new regressions (7 pre-existing HOF/xml-to-json failures)
• XPathQueryTest (150): all pass
• Full exist-core test suite (7835): zero new regressions
• XQ 3.1 maps.xqm:no-atomization still expects error (maps not atomizable in 3.1)
• XQ 3.1 cast-constructor.xqm:atomize-map-fails still expects FOTY0013
• XQTS QT4 runner verification (requires next-v3 integration with XQ4 parser)

Note: On develop, the isXq4Atomizable() check always returns false since the XQ4 parser support (v2/xq4-parser-extensions) is not yet merged. The code path activates when integrated into next-v3.

🤖 Generated with Claude Code

[reinhapa]

Use direct cast using local variable here:

Suggested change

	if (single instanceof AbstractMapType && ((AbstractMapType) single).isXq4Atomizable()) {
	return ((AbstractMapType) single).atomizeValues();
	}
	if (single instanceof AbstractMapType mapType && mapType.isXq4Atomizable()) {
	return mapType.atomizeValues();
	}

[reinhapa]

Same as above

Suggested change

	if (next instanceof AbstractMapType && ((AbstractMapType) next).isXq4Atomizable()) {
	result.addAll(((AbstractMapType) next).atomizeValues());
	if (next instanceof AbstractMapType mapType && mapType.isXq4Atomizable()) {
	result.addAll(mapType.atomizeValues());

[reinhapa]

Same here

Suggested change

	if (item instanceof AbstractMapType && ((AbstractMapType) item).isXq4Atomizable()) {
	final Sequence atomized = ((AbstractMapType) item).atomizeValues();
	if (item instanceof AbstractMapType mapType && mapType.isXq4Atomizable()) {
	final Sequence atomized = mapType.atomizeValues();

[joewiz]

[This response was co-authored with Claude Code. -Joe]

Thanks @reinhapa — addressed in b7c258c:

• Converted all 3 instanceof + cast patterns to Java 16+ pattern-matching instanceof in Atomize.java (2 locations) and ConcatExpr.java (1 location)