Mentor RDF Parsers

Standards-compliant, fault-tolerant parsers for RDF languages, built with Chevrotain. Designed for IDEs and language tools where error recovery and concrete syntax tree (CST) access are essential.

Features

• Standards Compliance — Implements grammar productions from W3C specifications
• Fault Tolerance — Recovers from syntax errors and continues parsing
• Concrete Syntax Trees — Full token access with positions for tooling
• RDF/JS Quads — Reader classes produce RDF/JS-compliant quads
• Blank Node Tracking — Pre-assigned IDs for IDE features like "go to definition"

Supported Languages

Language	Parser	Reader	Specification
N-Triples	✓	✓	RDF 1.2 N-Triples
N-Quads	✓	✓	RDF 1.2 N-Quads
Turtle	✓	✓	RDF 1.2 Turtle
TriG	✓	✓	RDF 1.2 TriG
N3	✓	✓	W3C N3
SPARQL 1.2	✓	—	SPARQL 1.2 Query

Installation

npm install @faubulous/mentor-rdf-parsers
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Quick Start

import { TurtleLexer, TurtleParser, TurtleReader } from '@faubulous/mentor-rdf-parsers';

const input = `
  @prefix ex: <http://example.org/> .
  ex:Alice ex:knows ex:Bob .
`;

// Tokenize → Parse → Read
const lexResult = new TurtleLexer().tokenize(input);
const cst = new TurtleParser().parse(lexResult.tokens);
const quads = new TurtleReader().visit(cst);

console.log(quads[0].subject.value); // "http://example.org/Alice"
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Architecture

flowchart LR
    A[Input String] --> B[Lexer]
    B -->|tokens| C[Parser]
    C -->|CST| D[Reader]
    D -->|quads| E[RDF/JS Quads]
    
    B -.->|lexing errors| F[errors]
    C -.->|parsing errors| F
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Component	Purpose
Lexer	Tokenizes input string into a token stream
Parser	Produces a concrete syntax tree (CST) from tokens
Reader	Walks the CST and produces RDF/JS Quad objects

Documentation

Examples by Language

Language	Guide
Turtle	docs/examples/turtle.md
N-Triples	docs/examples/n-triples.md
N-Quads	docs/examples/n-quads.md
TriG	docs/examples/trig.md
N3	docs/examples/n3.md
SPARQL	docs/examples/sparql.md

Advanced Topics

• Error Handling — Fault-tolerant parsing and error collection
• Blank Node IDs — Pre-assigned identifiers for IDE integration

Error Handling

Parsers collect errors instead of throwing, allowing partial results:

const parser = new TurtleParser();
const cst = parser.parse(tokens, false); // Pass false to collect errors

// Check all error sources
console.log(lexResult.errors);       // Lexer errors
console.log(parser.errors);          // Parser errors
console.log(parser.semanticErrors);  // Semantic errors (e.g., undefined prefixes)
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See Error Handling Guide for details.

Token Access

Each language exports its token array for use in formatters and syntax highlighters:

import { TurtleTokens, SparqlTokens } from '@faubulous/mentor-rdf-parsers';

console.log(TurtleTokens.map(t => t.name));
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Testing

npm test
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The test suite includes over 1,500 tests covering all supported languages and the official W3C conformance test suites.

License

LGPL-2.1-or-later