astgrepr
provides R bindings to the
ast-grep Rust crate. ast-grep
is a tool
to parse the abstract syntax tree (AST) of some code and to perform
search and rewrite of code. This is extremely useful to build linters,
stylers, and perform a lot of code analysis.
See the example below and the “Getting started”
vignette for a
gentle introduction to astgrepr
.
Since astgrepr
can be used as a low-level foundation for other tools
(such as linters), the number of R dependencies is kept low:
> pak::local_deps_tree()
✔ Loading metadata database ... done
local::. 0.0.1 [new][bld]
├─checkmate 2.3.1 [new][dl] (746.54 kB)
│ └─backports 1.5.0 [new]
├─rrapply 1.2.7 [new]
└─yaml 2.3.8 [new][dl] (119.08 kB)
Key: [new] new | [dl] download | [bld] build
install.packages('astgrepr', repos = c('https://etiennebacher.r-universe.dev', 'https://cloud.r-project.org'))
library(astgrepr)
src <- "library(tidyverse)
x <- rnorm(100, mean = 2)
any(duplicated(y))
plot(x)
any(duplicated(x))
any(is.na(variable))"
root <- src |>
tree_new() |>
tree_root()
# get everything inside rnorm()
root |>
node_find(ast_rule(pattern = "rnorm($$$A)")) |>
node_get_multiple_matches("A") |>
node_text_all()
#> $rule_1
#> $rule_1[[1]]
#> [1] "100"
#>
#> $rule_1[[2]]
#> [1] ","
#>
#> $rule_1[[3]]
#> [1] "mean = 2"
# find occurrences of any(duplicated())
root |>
node_find_all(ast_rule(pattern = "any(duplicated($A))")) |>
node_text_all()
#> $rule_1
#> $rule_1$node_1
#> [1] "any(duplicated(y))"
#>
#> $rule_1$node_2
#> [1] "any(duplicated(x))"
# find some nodes and replace them with something else
nodes_to_replace <- root |>
node_find_all(
ast_rule(id = "any_na", pattern = "any(is.na($VAR))"),
ast_rule(id = "any_dup", pattern = "any(duplicated($VAR))")
)
fixes <- nodes_to_replace |>
node_replace_all(
any_na = "anyNA(~~VAR~~)",
any_dup = "anyDuplicated(~~VAR~~) > 0"
)
# original code
cat(src)
#> library(tidyverse)
#> x <- rnorm(100, mean = 2)
#> any(duplicated(y))
#> plot(x)
#> any(duplicated(x))
#> any(is.na(variable))
# new code
tree_rewrite(root, fixes)
#> library(tidyverse)
#> x <- rnorm(100, mean = 2)
#> anyDuplicated(y) > 0
#> plot(x)
#> anyDuplicated(x) > 0
#> anyNA(variable)
There is some recent work linking tree-sitter
and R. Those are not
competing with astgrepr
but are rather a complement to it:
r-lib/tree-sitter-r
: provide the R grammar to be used with tools built ontree-sitter
.astgrepr
relies on this grammar under the hood.DavisVaughan/r-tree-sitter
: a companion ofr-lib/tree-sitter-r
. This gives a way to get the tree-sitter representation of some code directly in R. This is useful to learn how tree-sitter represents the R grammar, which is required if you want advanced use ofastgrepr
. However, it doesn’t provide a way to easily select specific nodes (e.g. based on patterns).