R/eval_utils.R

In twolodzko/lolplyr: Adapting dplyr for lists-of-lists

try_eval <- function(exprs, data = NULL, warn = TRUE) {
  if (!is_simple_list(data))
    stop("data is not a list")

  exprs <- quos_auto_name(exprs)

  idx <- structure(seq_along(exprs),
                   names = names(exprs))

  lapply(idx, function(i) {
    tryCatch({
      evl <- eval_tidy(exprs[[i]], data = data)
      data[[names(exprs)[i]]] <<- evl
      evl
    }, error = function(e) {
      if (warn)
        warning(e[[1]])
      NULL
    })
  })
}


try_select_vars <- function(vars, quos, warn = TRUE) {
  unlist(lapply(quos, function(q) {
    tryCatch({
      names(select_vars(vars, !!! q))
    }, error = function(e) {
      if (warn)
        warning(e[[1]])
      NULL
    })
  }))
}