helix-plus/book/src/guides/textobject.md

Adding Textobject Queries

Textobjects that are language specific (like functions, classes, etc) require an accompanying tree-sitter grammar and a textobjects.scm query file to work properly. Tree-sitter allows us to query the source code syntax tree and capture specific parts of it. The queries are written in a lisp dialect. More information on how to write queries can be found in the official tree-sitter documentation.

Query files should be placed in runtime/queries/{language}/textobjects.scm when contributing. Note that to test the query files locally you should put them under your local runtime directory (~/.config/helix/runtime on Linux for example).

The following captures are recognized:

Capture Name
function.inside
function.around
class.inside
class.around
parameter.inside

Example query files can be found in the helix GitHub repository.

Queries for Textobject Based Navigation

Tree-sitter based navigation is done using captures in the following order:

• object.movement
• object.around
• object.inside

For example if a function.around capture has been already defined for a language in it's textobjects.scm file, function navigation should also work automatically. function.movement should be defined only if the node captured by function.around doesn't make sense in a navigation context.