Crate railroad

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A library to create syntax (“railroad”) diagrams as Scalable Vector Graphics (SVG).

Railroad diagrams are a graphical way to represent context-free grammar. Every diagram has exactly one starting- and one end-point; everything that belongs to the described language is represented by one of the possible paths between those points.

Using this library, diagrams are created by primitives which implemented Node. Primitives are combined into more complex strctures by wrapping simple elements into more complex ones.

use railroad::*;

// This diagram will be a (horizontal) sequence of simple elements
let mut seq: Sequence<Box<dyn Node>> = Sequence::default();
seq.push(Box::new(Start))
   .push(Box::new(Terminal::new("BEGIN".to_owned())))
   .push(Box::new(NonTerminal::new("syntax".to_owned())))
   .push(Box::new(End));

// The library only computes the diagram's geometry; we use CSS for layout.
let mut dia = Diagram::new_with_stylesheet(seq, &Stylesheet::Light);

// A `Node`'s `fmt::Display` is its SVG.
println!("<html>{}</html>", dia);

Re-exports§

Modules§

Structs§

  • Choice
    A container of elements, drawn vertically, where exactly one element has to be picked
  • Comment
    A label / verbatim text, drawn in-line
  • Diagram
  • Empty
    A dummy-element which has no size and draws nothing.
  • End
    A symbol indicating the logical end of a syntax-diagram via two vertical bars.
  • HorizontalGrid
    A horizontal group of unconnected elements.
  • LabeledBox
    A box drawn around the given element and a label placed inside the box, above the element.
  • Link
    Wraps another primitive, making it a clickable link to some URI.
  • NonTerminal
    A NonTerminal, drawn as a rectangle.
  • Optional
    Wraps another element to make that element logically optional.
  • Repeat
    Wraps one element by providing a backwards-path through another element.
  • Sequence
    A horizontal group of elements, connected from left to right.
  • SimpleEnd
    A symbol indicating the logical end of a syntax-diagram via a circle
  • SimpleStart
    A symbol indicating the logical start of a syntax-diagram via a circle
  • Stack
    A vertical group of elements, drawn from top to bottom.
  • Start
    A symbol indicating the logical start of a syntax-diagram via two vertical bars.
  • Terminal
    A Terminal-symbol, drawn as a rectangle with rounded corners.
  • VerticalGrid
    A vertical group of unconnected elements.

Enums§

Constants§

  • DEFAULT_CSS
    Default Cascading Style Sheets for the resuling SVG.

Traits§

  • Node
    A diagram is built from a set of primitives which implement Node.
  • NodeCollection
    Helper trait for collections of nodes.