There must be better ways out there, but here's my attempt:
listFunctions <- function(function.name, recursive = FALSE,
checked.functions = NULL){
# Get the function's code:
function.code <- deparse(get(function.name))
# break code up into sections preceding left brackets:
left.brackets <- c(unlist(strsplit(function.code,
split="[[:space:]]*\\(")))
called.functions <- unique(c(unlist(sapply(left.brackets,
function (x) {
# Split up according to anything that can't be in a function name.
# split = not alphanumeric, not '_', and not '.'
words <- c(unlist(strsplit(x, split="[^[:alnum:]_.]")))
last.word <- tail(words, 1)
last.word.is.function <- tryCatch(is.function(get(last.word)),
error=function(e) return(FALSE))
return(last.word[last.word.is.function])
}))))
if (recursive){
# checked.functions: We need to keep track of which functions
# we've checked to avoid infinite loops.
functs.to.check <- called.functions[!(called.functions %in%
checked.functions)]
called.functions <- unique(c(called.functions,
do.call(c, lapply(functs.to.check, function(x) {
listFunctions(x, recursive = T,
checked.functions = c(checked.functions,
called.functions))
}))))
}
return(called.functions)
}
And the results:
> listFunctions("listFunctions", recursive = FALSE)
[1] "function" "deparse" "get" "c"
[5] "unlist" "strsplit" "unique" "sapply"
[9] "tail" "tryCatch" "is.function" "return"
[13] "if" "do.call" "lapply" "listFunctions"
> system.time(all.functions <- listFunctions("listFunctions", recursive = TRUE))
user system elapsed
92.31 0.08 93.49
> length(all.functions)
[1] 518
As you can see, the recursive version returns a lot of functions. The problem with this is it returns every function called in the process, which obviously adds up as you go. In any case, I hope you can use this (or modify it) to suit your needs.
