Shows the relationship between calls on the stack. This function
combines the results of sys.calls() and sys.parents() yielding a display
that shows how frames on the call stack are related.
Examples
# If all evaluation is eager, you get a single tree
f <- function() g()
g <- function() h()
h <- function() cst()
f()
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. └─f()
#> 27. └─g()
#> 28. └─h()
#> 29. └─lobstr::cst()
# You get multiple trees with delayed evaluation
try(f())
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. ├─base::try(f())
#> 27. │ └─base::tryCatch(...)
#> 28. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 29. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 30. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 31. └─f()
#> 32. └─g()
#> 33. └─h()
#> 34. └─lobstr::cst()
# Pay attention to the first element of each subtree: each
# evaluates the outermost call
f <- function(x) g(x)
g <- function(x) h(x)
h <- function(x) x
try(f(cst()))
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. ├─base::try(f(cst()))
#> 27. │ └─base::tryCatch(...)
#> 28. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 29. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 30. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 31. ├─f(cst())
#> 32. │ └─g(x)
#> 33. │ └─h(x)
#> 34. └─lobstr::cst()
# With a little ingenuity you can use it to see how NSE
# functions work in base R
with(mtcars, {cst(); invisible()})
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. ├─base::with(...)
#> 27. └─base::with.default(...)
#> 28. └─base::eval(substitute(expr), data, enclos = parent.frame())
#> 29. └─base::eval(substitute(expr), data, enclos = parent.frame())
#> 30. └─lobstr::cst()
invisible(subset(mtcars, {cst(); cyl == 0}))
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. ├─base::subset(...)
#> 27. └─base::subset.data.frame(...)
#> 28. └─base::eval(e, x, parent.frame())
#> 29. └─base::eval(e, x, parent.frame())
#> 30. └─lobstr::cst()
# You can also get unusual trees by evaluating in frames
# higher up the call stack
f <- function() g()
g <- function() h()
h <- function() eval(quote(cst()), parent.frame(2))
f()
#> ▆
#> 1. └─pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
#> 2. └─pkgdown::build_site(...)
#> 3. └─pkgdown:::build_site_local(...)
#> 4. └─pkgdown::build_reference(...)
#> 5. └─purrr::map(...)
#> 6. └─pkgdown .f(.x[[i]], ...)
#> 7. ├─base::withCallingHandlers(...)
#> 8. └─pkgdown:::data_reference_topic(...)
#> 9. └─pkgdown:::run_examples(...)
#> 10. └─pkgdown:::highlight_examples(code, topic, env = env)
#> 11. └─downlit::evaluate_and_highlight(...)
#> 12. └─evaluate::evaluate(code, child_env(env), new_device = TRUE, output_handler = output_handler)
#> 13. └─evaluate:::evaluate_call(...)
#> 14. ├─evaluate timing_fn(...)
#> 15. ├─evaluate handle(...)
#> 16. │ └─base::try(f, silent = TRUE)
#> 17. │ └─base::tryCatch(...)
#> 18. │ └─base tryCatchList(expr, classes, parentenv, handlers)
#> 19. │ └─base tryCatchOne(expr, names, parentenv, handlers[[1L]])
#> 20. │ └─base doTryCatch(return(expr), name, parentenv, handler)
#> 21. ├─base::withCallingHandlers(...)
#> 22. ├─base::withVisible(...)
#> 23. └─evaluate:::eval_with_user_handlers(expr, envir, enclos, user_handlers)
#> 24. └─base::eval(expr, envir, enclos)
#> 25. └─base::eval(expr, envir, enclos)
#> 26. └─f()
#> 27. ├─g()
#> 28. │ └─h()
#> 29. │ └─base::eval(quote(cst()), parent.frame(2))
#> 30. │ └─base::eval(quote(cst()), parent.frame(2))
#> 31. └─lobstr::cst()