helix/book/src/guides/injection.md

Adding Injection Queries

Writing language injection queries allows one to highlight a specific node as a different language. In addition to the standard language injection options used by tree-sitter, there are a few Helix specific extensions that allow for more control.

And example of a simple query that would highlight all strings as bash in Nix:

((string_expression (string_fragment) @injection.content)
  (#set! injection.language "bash"))

Capture Types

• @injection.language (standard): The captured node may contain the language name used to highlight the node captured by @injection.content.

• @injection.content (standard): Marks the content to be highlighted as the language captured with @injection.language et al.

• @injection.filename (extension): The captured node may contain a filename with a file-extension known to Helix, highlighting @injection.content as that language. This uses the language extensions defined in both the default languages.toml distributed with Helix, as well as user defined languages.

• @injection.shebang (extension): The captured node may contain a shebang used to choose a language to highlight as. This also uses the shebangs defined in the default and user languages.toml.

Settings

• injection.combined (standard): Indicates that all the matching nodes in the tree should have their content parsed as one nested document.

• injection.language (standard): Forces the captured content to be highlighted as the given language

• injection.include-children (standard): Indicates that the content node’s entire text should be re-parsed, including the text of its child nodes. By default, child nodes’ text will be excluded from the injected document.

• injection.include-unnamed-children (extension): Same as injection.include-children but only for unnamed child nodes.

Predicates

• #eq? (standard): The first argument (a capture) must be equal to the second argument (a capture or a string).

• #match? (standard): The first argument (a capture) must match the regex given in the second argument (a string).