[Simon GAY (simnJS)]

Adds a Monarch tokenizer for Verse, the programming language Epic Games created for Unreal Editor for Fortnite (UEFN), for *.verse files.

Relevance

• Epic has announced that Unreal Engine 6 merges Unreal Engine 5 and UEFN, with Verse as its gameplay programming language (The road to Unreal Engine 6).
• GitHub Linguist recognizes Verse (*.verse), and Chroma has a Verse lexer (feat(lexers): add Verse lexer alecthomas/chroma#1412).
• Wikipedia covers Verse in the Verse section of the Unreal Engine article.

Changes

• src/languages/definitions/verse/: register.ts, verse.ts (tokenizer and language configuration) and verse.test.ts.
• src/languages/definitions/register.all.ts: registers the language.
• website/src/website/data/home-samples/sample.verse.txt: sample from simnJS/verse-grammar, plus an indented comment.

The token rules follow the Verse grammar that Epic Games publishes under CC0 in verselang/book, like the Verse lexers I contributed to Pygments (pygments/pygments#3422) and Chroma.

Tokens

• Comments: # line comments, nested <# ... #> block comments, and <#> indented comments. An indented comment covers the following lines that are indented deeper than the <#> line; the tokenizer keeps that indentation in the state name and matches it with $S2.
• Block comments inside strings are comments, since Verse removes them from the string value ("ab<#x#>cd" = "abcd").
• Strings with {...} interpolation (nested braces, strings inside the interpolation, interpolation that continues on the next line), the escapes \t \n \r \" \' \\ \{ \} \< \> \& \# \~, invalid escapes and unterminated strings.
• Characters: 'a', '\n', '😀', 0o61, 0u1F600.
• Numbers: decimal, hex, floats with exponent, suffixes such as 12.34f64, and ranges like 0..9.
• Specifiers (<public>, <decides>, <scoped{...}>, <getter(...)>) and attributes (@editable) as annotation. Comparisons such as A<B, B>C stay operators.
• Keywords, built-in types (keyword.type), operators, and paths in using { /Verse.org/Simulation }, import(...) and (/Verse.org/Random:) qualifiers (constant.path).

The language configuration sets # and <# #> for comment toggling, indents after a line ending in : or =, and uses off-side folding.

Testing

• npm test: all tokenization tests pass, including the new verse cases (each comment form, interpolation with nested braces, a comment inside a string, specifiers next to identifiers, comparisons that are not specifiers, paths), and the sample check passes.
• npm run build, npm run compile --prefix webpack-plugin and npm run package-for-smoketest pass; Verse is in the webpack, esbuild and Vite bundles. I did not run the Playwright smoke tests locally.
• Checked the sample in a local page built from out/monaco-editor, with the vs and vs-dark themes: Enter after a line ending in : or = indents, and the comment commands insert # and <# ... #>.

[Simon GAY (simnJS)]

@microsoft-github-policy-service agree