bonsaisitter

Bindings to the tree-sitter parsing library for R. The API mirrors the treesitter package, so bonsaisitter:: can stand in for treesitter:: in existing code. The package depends on nothing beyond base R.

bonsaisitter is the runtime only. Grammars come from separate packages:

Installation

install.packages("bonsaisitter")

Development builds and the grammar packages that are not on CRAN are in the cornball.ai drat repository:

install.packages(c("bonsaisitter", "treesitter.python"),
                 repos = "https://cornball-ai.github.io/drat")

Usage

library(bonsaisitter)

lang <- treesitter.r::language()
tree <- text_parse("x <- f(1, 2)", lang)
root <- tree_root_node(tree)

node_type(root)
#> [1] "program"

q <- query(lang, "(call function: (identifier) @fn)")
vapply(query_captures(q, root)$node, node_text, character(1))
#> [1] "f"

cursor <- tree_walk(tree)
cursor$goto_first_child()
node_type(cursor$node())
#> [1] "binary_operator"

Differences from treesitter

• The R6 TreeCursor is replaced by tree_walk() and node_walk(), which return an environment of closures with the same method names (cursor$goto_first_child(), cursor$node(), and so on).
• query_matches() returns a flat list of matches instead of nesting them by pattern.
• Query predicates such as #eq? and #match? are not applied; query_captures() returns every capture.

Extras

• literals_and_calls() and audit_translation() compare the numeric literals and call names of a source file and its port, for example Python code and its R translation, and report the constants that drifted.
• as.data.frame() on a node gives one row per descendant, with type, text and position columns.

License

MIT, copyright cornball.ai. The bundled tree-sitter sources are MIT, copyright Max Brunsfeld; every holder is listed in inst/COPYRIGHTS.