Ruby 3.1+ · Rouge 5

Highlight the edit. Keep the rest.

Antares gives Rouge line-oriented, edit-aware syntax highlighting. Restore measured lexer state, scan until output converges, and reuse the untouched suffix.

Install the gem Read the API
One-line edit frontier: 132 
# checkpoint restored at line 64
+ status = :ready
highlighter.edit(
  from_line: 128, removed: 1, inserted: 1
)
# state converged — cached suffix reused
checkpoint 64 edit 128 converged 131
Lexers measured
234
Incremental
110
Bounded window
124
Runtime dependency
1

Work follows the edit

Each request does only the lexical work needed to prove the current lines are correct.

  1. 1Restore

    Resume from the nearest reusable lexer-state checkpoint.

  2. 2Scan

    Tokenize forward from the changed line under explicit limits.

  3. 3Converge

    Stop when lexer state and tokens match the cached document.

  4. 4Reuse

    Keep the proven, untouched suffix instead of highlighting it again.

Add it to your editor

Keep document storage and colors in your application. Antares returns frozen Rouge token rows.

Full documentation
Gemfile 
gem "antares"
Ruby 
highlighter = Antares::Highlighter.new(
  lexer: Rouge::Lexers::Python.new,
  lines: ->(index) { lines[index] },
  line_count: -> { lines.length }
)

highlighter.tokens_in(0..20)