xq-parser

An extensible parser framework for everything in the XQuery / XPath family. With vendor-specific extensions. Implements both XQuery 3.1 and XQuery 4.

Based on the amazing Rex parser generator.

| Vendor | Specification | Implementation state | |-----|-----|-----| | Exist-DB | XQuery Update extension | Implemented in both XQuery 3 and 4. Sponsored by Exist Solutions | | XQuery Update Facility | XQUF 30 | Implemented, experimental in XQuery 4. Open for sponsorship | | BaseX | XQuery Extensions | Not implemented. Open for sponsorship | | MarkLogic | MarkLogic Server Enhanced XQuery Language | Not implemented. Open for sponsorship |

Regenerating the parsers

The parsers in parsers/XQuery-40-full.ts and parsers/XQuery-31-full.ts are generated from EBNF grammars using the REx parser generator. The raw grammars live in rawgrammars/ and the transformation pipeline lives in src/.

Steps to regenerate

1. Clone and build REx (requires g++):

   git clone https://github.com/GuntherRademacher/rex-parser-generator.git
   cd rex-parser-generator
   rex/scripts/build-gpp.sh
   cd ..

2. Run the generator script from the repo root:

   ./generate-parsers.sh

   This script:

   • Transforms rawgrammars/XQuery-40.ebnf → transformedgrammars/XQuery-40-full.ebnf (applying XQUF and eXist-DB mutations via src/index.ts)
   • Runs rex -typescript -glalr 1 -a pi -tree on each transformed grammar
   • Prepends parser_header.txt and writes the result to parsers/

3. Verify by running the test suite:

   npm test
   # or, with the W3C conformance tests:
   QT4_TESTS_DIR=qt4tests npm test

Updating the raw grammar

The XQuery 4.0 raw grammar is periodically refreshed from the upstream REx sample:

https://raw.githubusercontent.com/GuntherRademacher/rex-parser-generator/main/docs/sample-grammars/XQuery-40.ebnf

A CI workflow (update-xquery-4-ebnf.yml) can be triggered manually via workflow_dispatch to download the latest grammar, apply the transformations, run REx, and open a pull request with the result.

The XQuery 3.1 grammar (rawgrammars/XQuery-31.ebnf) is maintained manually.