goxpath

An XPath 3.1 evaluator written in Go — 85% W3C conformance (~19,000 of ~22,200 applicable QT3 tests passing).

Built on goxml for the XML tree model.

Features

• Full XPath 3.1 expression language (let, for, if, arrow, maps, arrays, inline functions, dynamic calls)
• 150+ XPath/XQuery functions including math, higher-order, JSON, date/time formatting
• Typed numeric system (xs:double, xs:float, xs:decimal, xs:integer with subtype hierarchy)
• Named function references, dynamic function calls, function-lookup
• DecimalFormat API for customizable number formatting
• Per-test regression detection against a W3C QT3 baseline

Usage

xp, _ := goxpath.NewParser(strings.NewReader(`<root><item id="1">Hello</item></root>`))
result, _ := xp.Evaluate("//item[@id='1']/text()")
fmt.Println(result) // [Hello]

See pkg.go.dev for the full Go API.

Testing

# Run all tests including W3C QT3 conformance (~2s)
git clone --depth 1 https://github.com/w3c/qt3tests.git testdata/qt3tests
go test ./...

# Update baseline after improvements
QT3_UPDATE_BASELINE=1 go test -run TestQT3Survey

The test suite compares each run against testdata/qt3_baseline.txt (~19,000 test names). Any regression is reported as a test failure with the specific test name.

Known Limitations

• Regex back-references (\1, \2) are not supported (Go RE2 engine limitation)
• Unicode Collation Algorithm (UCA): supported via golang.org/x/text/collate. lang, strength, numeric and fallback parameters are honored; caseFirst, caseLevel, alternate, maxVariable, reorder, backwards, version, normalization are accepted lax but not effectively applied (raise FOCH0002 with fallback=no).
• Integer precision is limited to int64 (~9.2 × 10¹⁸); the spec requires arbitrary precision
• Decimal is stored as float64 (~15-17 significant digits)
• Timezone handling may add or omit timezone indicators in edge cases
• Not implemented: fn:transform(), fn:idref(), namespace:: axis, schema-aware types

See the full limitations reference for details.

Documentation

Full reference at https://doc.speedata.de/goxml/ — includes language features, type system, all function categories, Go API, and known limitations.

Ecosystem

goxpath is part of a broader ecosystem of PDF, typesetting and publishing technologies.

Explore the constellation →

License

BSD-3-Clause — see License.md.