seeking to use call_tree to get a list object

[harryprince]

I am seeking to catch pryr::call_tree output, definitely, I failed.
Because I find the call_tree function use cat function to throw output.

I am trying to use pryr::call_tree to analysis the abstract grammar tree to leverage the power of %>% in dplyr to plot the function and data relationship, which is called DAG.

I found %>% have a great nature than other languages, when I am using Airflow, a Python workflow secheduler, the process of describing DAG is so tedious and I think it can be done in R in an elegant way.

In that, I am seeking a way to catch the abstract grammar tree in a list object or two data frame, which called as graph frame, to plot the workflow using ggplot2. And the key problem is how to get the list object...need your help.

>pryr::call_tree
function (x, width = getOption("width")) 
{
    if (is.expression(x) || is.list(x)) {
        trees <- vapply(x, tree, character(1), width = width)
        out <- str_c(trees, collapse = "\n\n")
    }
    else {
        out <- tree(x, width = width)
    }
    cat(out, "\n")
}
<environment: namespace:pryr>

what I am trying

> abc <- function(x) {
+   if (is.expression(x) || is.list(x)) {
+     trees <- vapply(x, tree, character(1), width = width)
+     out <- str_c(trees, collapse = "\n\n")
+   }
+   else {
+     out <- tree(x, width = width)
+   }
+   return(out)
+ }
> abc(123+2123)
Error in abc(123 + 2123) : could not find function "tree"