Merge pull request rstudio#74 from rstudio-education/compare_default_…

…formals

Add function formals when comparing and standarising code for comparison

R/call_standarise_formals.R

@@ -0,0 +1,33 @@
+call_standardise_formals <- function(code, env = rlang::current_env()) {
+  # browser()
+
+  # try to catch invalid function, i.e., corrupt language object
+  tryCatch({
+    fxn <- rlang::call_fn(code, env = env)
+  }, error = function(e) {
+    return(code)
+  })
+  if (!exists("fxn")) {return(code)} ## some reason the above tryCatch doesn't go to the error part
+  if(class(fxn) != "function") {return(code)}
+
+  # standarise, but dont bother trying to fill out default formals
+  # for primitives like mean, unable to distinguish between mean and mean.default
+  if (is_infix(code) || is.primitive(fxn)) {
+    return(rlang::call_standardise(code))
+  }
+
+  forms <- rlang::fn_fmls(fxn)
+  default_params <- forms[!vapply(forms, is.symbol, logical(1), USE.NAMES = FALSE)]
+
+  code_std <- rlang::call_standardise(code, env = env) # order and label existing params
+
+  code_params <- rlang::call_args(code_std) # get arguments passed from user
+  code_missing_default_args <- default_params[!names(default_params) %in% names(code_params)]
+  if (length(code_missing_default_args) == 0) {
+    return(code_std)
+  }
+  return(
+    rlang::call_standardise(rlang::call_modify(code_std, !!!code_missing_default_args),
+                            env = env)
+  )
+}