Find global/local variables in R code — find

Use codetools::findGlobals() and codetools::findLocalsList() to find global and local variables in a piece of code. Global variables are defined outside the code, and local variables are created inside the code.

find_globals(code, envir = parent.frame())

find_locals(code)

Arguments

code: Either a character vector of R source code, or an R expression.
envir: The global environment in which global variables are to be found.

Value

A character vector of the variable names. If the source code contains syntax errors, an empty character vector will be returned.

Note

Due to the flexibility of creating and getting variables in R, these functions are not guaranteed to find all possible variables in the code (e.g., when the code is hidden behind eval()).

Examples

x = 2
xfun::find_globals("y = x + 1")
#> [1] "x"
xfun::find_globals("y = get('x') + 1")  # x is not recognized
#> character(0)
xfun::find_globals("y = zzz + 1")  # zzz doesn't exist
#> character(0)

xfun::find_locals("y = x + 1")
#> [1] "y"
xfun::find_locals("assign('y', x + 1)")  # it works
#> [1] "y"
xfun::find_locals("assign('y', x + 1, new.env())")  # still smart
#> character(0)
xfun::find_locals("eval(parse(text = 'y = x + 1'))")  # no way
#> character(0)