Grammar Railroad Diagrams

Intro

Reading EBNF grammars is not easy. Seeing it on a “rail-road” diagram makes it easier to understand the grammar.

• https://github.com/GuntherRademacher/rr is an excellent tool to produce diagrams: it can scrape EBNF grammars from W3C specs, generates either a single XHTML with embedded SVG, or a zip with many PNGs, cross-links the definitions and usages.
• https://www.bottlecaps.de/rr/ui is a deployed version
  • (It was deployed at https://rr.red-dove.com/ui for a while)
• INCOMPLETE: ./ebnf2tdv.pl: convert ebnf to a list of node-node connections, for visualizing eg with d3

Table of Contents

• Intro
• SPARQL Query and Update
  • SPARQL 1.1 Railroad Diagram
  • SPARQL 1.2 Railroad Diagram
  • SPARQL-star Railroad Diagram
  • Chunked SPARQL Diagram
• SHACLC Compact
• SHACL Rules
• XSPARQL

SPARQL Query and Update

I use this quite often while writing SPARQL. It is bit hard to understand: use this for reference, but not for learning SPARQL.

SPARQL 1.1 Railroad Diagram

SPARQL 1.1 is the current version of SPARQL.

• sparql11-grammar.xhtml: Cross-linked diagrams, one per production (173 total).
• sparql11-grammar.ebnf: EBNF rules extracted from the spec
• sparql11-grammar.txt: same thing but with production numbers
• extracted from: http://www.w3.org/TR/sparql11-query/
• version: http://www.w3.org/TR/2013/REC-sparql11-query-20130321/
• created on: Apr 2, 2013

Preview:

SPARQL 1.2 Railroad Diagram

SPARQL 1.2 is the long-awaited update of SPARQL with SPARQL-star (reified triples and annotations). It’s still a work in progress.

• sparql12-grammar.xhtml: Cross-linked diagrams, one per production (190 total).
• sparql12-grammar.ebnf: EBNF rules extracted from the spec
• sparql12-grammar.txt: same thing but with production numbers
• extracted from: https://www.w3.org/TR/sparql12-query/
• version: https://www.w3.org/TR/2024/WD-sparql12-query-20240921/
• created on: Oct 9, 2024

Preview:

SPARQL-star Railroad Diagram

This is an older incarnation of SPARQL-star. You can ignore it.

• sparql-star-grammar.xhtml: Cross-linked diagrams, one per production (173 total).
• sparql-star-grammar.ebnf: EBNF rules extracted from the spec
• sparql-star-grammar.txt: same thing but with production numbers
• extracted from: https://www.w3.org/2021/12/rdf-star.html#sparql-star-ebnf
• version: 2021-12-17

Preview:

Chunked SPARQL Diagram

Here’s a chunked diagram, which however is partial: Discussion whether there’s a chunked generator. Preview:

SHACLC Compact

SHACL Compact grammar

• shaclc-grammar.xhtml: Cross-linked diagrams, one per production (73 total)
• shaclc-grammar.ebnf: EBNF rules converted from the original ANTRL grammar
• Extracted from: https://w3c.github.io/shacl/shacl-compact-syntax/

Preview:

IMPORTANT: The SHACL CG is currently working on extending the SHACLC grammar with more features. You can see diagrams for 4 candidate grammars at https://github.com/VladimirAlexiev/shacl/tree/shaclc-grammars/shacl-compact-syntax/grammar#candidate-shacl-c-grammars

SHACL Rules

Proposed SHACL Rules grammar for SHACL Compact by Andy Seaborne: https://raw.githack.com/w3c/data-shapes/initial-infer-rules/shacl12-inf-rules/index.html#shapes-rules-grammar

• shacl-rules-grammar.xhtml

Preview:

XSPARQL

XSPARQL is a melding of XQuery and SPARQL. Its syntax is pretty large, so the diagrams help. https://github.com/VladimirAlexiev/xsparql/blob/master/doc/:

• grammar.xhtml: grammar diagram (XHTML+SVG, 950Kb)
  • grammar-nonterminals.xhtml: non-terminal symbols only (800Kb)
• grammar.html: original grammar, shows additions with bold and deletions with strikethrough
• grammar.ebnf: EBNF (text) extracted from above, renamed eg TriplesSameSubject’ to TriplesSameSubject1 because the tool cannot handle ’ as identifier char
  • grammar-nonterminals.ebnf: non-terminal symbols only

Preview: