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Ruby Templates

Supported syntax

Published by x_ror

What the grammars highlight and what the language server parses. The server follows Erubi as Rails configures it, Haml 7.5 and Slim 5.2.

ERB

Section titled “ERB”
Syntax Highlighting Server
<% %> Ruby Code, no output
<%- %> Ruby Same as <%
<%= %> Ruby Escaped output
<%== %> Ruby Unescaped output
<%# %> Comment Comment
<%# locals: (user:) %> Strict locals, as Ruby Strict locals checks, renames, completion
-%>, =%> Tag end Tag end (=%> as -%>, as in Erubi)
<%%, %%> Literal <% / %> Text, not a tag
<%_, _%> Not special: _ starts the Ruby code Not special, as in Erubi (code _ x _)
% lines Only in erb-percent Only in erb-percent (trim_mode: "%")
app/views/posts/_post.html.erb
<%# locals: (post:) %>
<article id="<%= dom_id(post) %>">
  <h2><%= post.title %></h2>
  <%== post.body_html %>
  <% if post.draft? -%>
    <p>Draft</p>
  <% end -%>
</article>

Trim modes

Section titled “Trim modes”

Erubi’s trim: true, the Rails default, is what the server models, so - before %> changes nothing in the checks. trim_mode: "%" is the opt-in erb-percent language id; other stdlib modes (<>, >) are not modelled.

Haml

Section titled “Haml”
Syntax Highlighting Server
%tag, .class, #id, !!!, /, -#, =, -, ~, &=, !=, #{} yes Parsed as Haml 7.5.1 does, with its error messages
Attributes {…}, (…), […] yes Parsed; Ruby inside is checked
Filters :plain :escaped :preserve :cdata Text Accepted
Filters :javascript :css :sass :scss :less :markdown :erb Embedded language Accepted
Filters :coffee :coffeescript CoffeeScript Accepted
Filter :ruby Ruby Accepted, body checked as Ruby
Any other filter (Haml 5’s :maruku, :textile, …) Text unknown-filter
succeed, precede, surround, preserve, find_and_preserve Ruby Completion and hover (Haml 6/7 RailsHelpers), Haml files only
app/views/posts/show.html.haml
%article{ id: dom_id(@post) }
  %h2.title= @post.title
  -# Rendered from Markdown
  :markdown
    #{@post.summary}
  = succeed "." do
    = link_to "Read more", post_path(@post)

Haml 6 and 7 are targeted (Haml 7.5.1 is the reference); Haml 5 is not. Whether a filter’s gem (sass, coffee-script, …) is installed isn’t checked.

Slim and Skim

Section titled “Slim and Skim”
Syntax Highlighting Server
Tags, .class/#id shortcuts, =, ==, -, /, |, ', doctype, #{} yes Parsed as Slim 5.2 does, with its error messages
Attribute wrappers (…), […], {…}, or none yes Parsed; Ruby inside is checked
Engines ruby: javascript: css: sass: scss: coffee: markdown: textile: rdoc: asciidoc: Embedded language where VS Code has one Accepted
Other engines: erb:, less:, stylus:, … Highlighted unknown-engine unless listed in rubyTemplates.slim.extraEngines
Engines your app registers (mjml:) Text Accepted once added to rubyTemplates.slim.extraEngines
app/views/posts/show.html.slim
article id=dom_id(@post)
  h2.title = @post.title
  / Rendered from Markdown
  markdown:
    #{@post.summary}
  | Posted by #{@post.author.name}

.skim files use the Slim syntax and the slim settings. Slim options set per app (custom shortcuts, attribute delimiters, smart text, logic-less mode) are not read.