highlightjs/highlight.js

(Ruby) #{} substitution shouldn't be highlighted in single quotes

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#3,676 opened on Dec 12, 2022

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Description

Describe the issue In Ruby, single quote and double quote strings work differently:

In addition to disabling interpolation [(#{} syntax)], single-quoted strings also disable all escape sequences except for the single-quote (\') and backslash (\\).

https://docs.ruby-lang.org/en/3.1/syntax/literals_rdoc.html#label-Strings

But in ruby.js, they are implemented identically

https://github.com/highlightjs/highlight.js/blob/9c49a4298a981e960b6d112c746d998d51e1d1e8/src/languages/ruby.js#L132-L139

which leads it to incorrectly highlight #{} substitutions in single quoted strings which actually have no effect, they are just literal #{} characters (in the "github" theme):

instead of highlighting it as a string, like it does if we remove the #:

Which language seems to have the issue? Ruby

Are you using highlight or highlightAuto? N/A

Expected behavior Single and double quoted strings should have separate highlighting rules for Ruby.

Additional context https://docs.ruby-lang.org/en/3.1/syntax/literals_rdoc.html#label-Strings

Unrelated, but for double quoted strings, that page also lists a couple interpolation syntax shorthands that are not implemented in the highlight.js grammar:

You can also use #@foo, #@@foo and #$foo as a shorthand for, respectively, #{ @foo }, #{ @@foo } and #{ $foo }.

Contributor guide

Tech stack
javascript
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of Ruby string quotingFamiliarity with highlight.js language grammar
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Examine the issue's code reference: src/languages/ruby.js lines 132-139, where single and double quoted strings share a common regex. Study the Ruby documentation link provided for difference in interpolation rules. Identify how to distinguish single quote strings in the grammar (likely separate rule or use of lookahead). Update the grammar to prevent interpolation highlighting in single quoted strings. Optionally implement the shorthand interpolation syntax for double quoted strings as mentioned. Test with sample Ruby code to ensure correctness.
(Ruby) #{} substitution shouldn't be highlighted in single quotes · highlightjs/highlight.js#3676 | Good First Issue