Confluent Orthogonal Drawings of Syntax Diagrams

TL;DR

This paper presents a pipeline for generating aesthetically pleasing syntax diagrams from context free grammars by combining various drawing styles and applying grammar-preserving heuristics.

Contribution

It introduces a novel pipeline that integrates multiple drawing styles and heuristics to produce improved syntax diagrams from context free grammars.

Findings

Effective heuristics improve diagram aesthetics

Combines confluent, layered, and orthogonal drawing styles

Formalizes syntax diagrams as automata sets

Abstract

We provide a pipeline for generating syntax diagrams (also called railroad diagrams) from context free grammars. Syntax diagrams are a graphical representation of a context free language, which we formalize abstractly as a set of mutually recursive nondeterministic finite automata and draw by combining elements from the confluent drawing, layered drawing, and smooth orthogonal drawing styles. Within our pipeline we introduce several heuristics that modify the grammar but preserve the language, improving the aesthetics of the final drawing.