Vue Railroad Diagram

VueRailroadDiagram is a Vue.js component, powered by tabatkins' railroad diagrams js library, creating SVG syntax diagrams from JSON grammars.

Installation

Typically, installing vue-railroad-diagram via npm i vue-railroad-diagram should work for most Vue.js systems.

However, this library is also available from unpkg at https://unpkg.com/vue-railroad-diagram.

For those needing an es module format, this too is available (it should be automatically imported by rollup or webpack, but is available at dist/vue-railroad-diagram.esm.js). Please note that this is produced by the build script (build:es), which will be available via npm, a la Travis CI, but not from GitHub.

Finally, the single file component (SFC), is available at src/railroad-diagram.vue. Please use import MyComponent from 'vue-railroad-diagram/sfc' if you would prefer the SFC.

Usage

Overall, vue-railroad-diagram is a relatively simple component, using two slots to draw the desired diagram.

Example

The following is an example of a JSON object described by a railroad diagram:

<template>
  ...
    <!-- Note that <vue-railroad-diagram /> also works -->
    <VueRailroadDiagram :options="diagramOpts" :grammar="grammar" />
  ...
</template>
 
<script>
import VueRailroadDiagram from "vue-railroad-diagram";
...
export default {
  ...
  data() {
    return {
      ...
      diagramOpts: {
        isStack: true,
        isComplex: true
      },
      grammar: [
        { type: "terminal", text: "{" },
        {
          type: "multiple",
          optional: true,
          repeat: ",",
          skip: false,
          children: [
            { type: "nonTerminal", text: "string" },
            { type: "terminal", text: ":" },
            { type: "nonTerminal", text: "value" }
          ]
        },
        { type: "terminal", text: "}" }
      ],
      ...
    }
  },
  ...
  components: {
    ...
    VueRailroadDiagram
    ...
  },
  ...
}
</script>

Slots

Of the two slots are options and grammar

options

The options slot is an optional slot, defaulting to the following:

{
  isStack: true,
  isComplex: true
}

options is an object which consists of two booleans, isStack and isComplex, isStack describing whether the diagram should be rendered as a vertical stack or horizontal sequency, and isComplex describing whether the diagram has "Complex" starts and ends or not.

grammar

The grammar is a non-optional slot. This is a sample, describing a JSON object:

[
  { type: "terminal", text: "{" },
  {
    type: "multiple",
    optional: true,
    repeat: ",",
    skip: false,
    children: [
      { type: "nonTerminal", text: "string" },
      { type: "terminal", text: ":" },
      { type: "nonTerminal", text: "value" }
    ]
  },
  { type: "terminal", text: "}" }
]

grammar is an array which describes each step of the railroad diagram. Steps consist of a type portion (type), data portion (eg. text, skip, etc.), and a a child/children portion (either child or children - N/A if step is a leaf).

Development

This component still has missing features. Below is todo list for what needs to be added. However, to preview you changes locally, @vue/cli-service-global must be installed globally (npm install -g @vue/cli-service-global or yarn global add @vue/cli-service-global). After installing this, vue serve ./dev/tester.vue can be run.

Todo

• Fix hrefs on the text leaf elements (terminal, nonTerminal, & comment)
• Add tests (and proper quick development system)
• Make grammar a required prop
• Add more rigorous documentation
• Allow for stack to be used in any container
• Add support for MultipleChoice() and HorizontalChoice() (as part of choice)
• Add Diagram() options:
  • VERTICAL_SEPARATION
  • ARC_RADIUS
  • DIAGRAM_CLASS
  • STROKE_ODD_PIXEL_LENGTH
  • INTERNAL_ALIGNMENT
• Add custom CSS options (ie. completely customized or just selected options)

Testing and Coverage

When contributing, please, at the very least, ensure that the preexisting tests still pass, using Jest, the test runner.

Running the provided test script (do not run npm test, as it is designed to run on CI):

npm run test:watch # This both watches all files and generates test coverage 
 
# Optionally run this in a second terminal (for coverage preview)  
cd coverage/lcov-report
npx http-server # Or your favorite auto-refreshing server 

Running a global instance of Jest (discouraged):

npm i -g jest # Installs jest 
jest # Runs jest 

Committing

VueRailroadDiagram is commitizen friendly, making commits as simple as running npm run commit and following the prompts. However, git commit -m "..." is still acceptable.