force line break after function declaration. Potentially high speed implications because another visitor call is needed.

Author: lorenzwalthert

R/rules-line-break.R

@@ -22,7 +22,10 @@ style_line_break_around_curly <- function(strict, pd) {
     opening_before <- (pd$token == "'{'") & (pd$token_after != "COMMENT")
     to_break <- lag(opening_before, default = FALSE) | closing_before
     len_to_break <- sum(to_break)
-    pd$lag_newlines[to_break] <- ifelse(rep(strict, len_to_break),
+    pd$lag_newlines[to_break] <- ifelse(
+      # only one case in which ) before {: functino declaration. Rule not
+      # enforced if for edge case function() # \n {}
+      rep(strict & !pd$token_before[1] == "')'", len_to_break),
       1L,
       pmax(1L, pd$lag_newlines[to_break])
     )
@@ -52,6 +55,14 @@ remove_line_break_before_round_closing_fun_dec <- function(pd) {
   pd
 }
 
+set_line_break_after_fun_dec_header <- function(pd) {
+  if (any(pd$token == "FUNCTION") && pd$child[[nrow(pd)]]$token[1] == "'{'") {
+    pos <- next_non_comment(pd, 1)
+    pd$child[[nrow(pd)]]$lag_newlines[pos] <- 2L
+  }
+  pd
+}
+
 
 #' @importFrom rlang seq2
 add_line_break_after_pipe <- function(pd) {

R/style-guides-mlr.R

@@ -98,7 +98,8 @@ mlr_style <- function(scope = "tokens",
                                               strict
       ),
       remove_line_break_in_empty_fun_call,
-      add_line_break_after_pipe
+      add_line_break_after_pipe,
+      set_line_break_after_fun_dec_header
     )
   }
 

R/transform-files.R

@@ -209,9 +209,9 @@ parse_transform_serialize_r <- function(text, transformers) {
 #' @keywords internal
 apply_transformers <- function(pd_nested, transformers) {
   transformed_line_breaks <- pre_visit(
-    pd_nested,
-    c(transformers$initialize, transformers$line_break)
-  )
+    pd_nested, c(transformers$initialize)
+  ) %>%
+    pre_visit(c(transformers$line_break))
 
   transformed_updated_multi_line <- post_visit(
     transformed_line_breaks,

tests/testthat/mlr-style/line-break-after-fun-dec-in.R

@@ -0,0 +1,6 @@
+function() {
+  x
+}
+
+function(x) x
+

tests/testthat/mlr-style/line-break-after-fun-dec-in_tree

@@ -0,0 +1,6 @@
+function() {
+
+  x
+}
+
+function(x) x

tests/testthat/mlr-style/line-break-after-fun-dec-out.R

@@ -0,0 +1,3 @@
+function() {
+  x
+}

tests/testthat/mlr-style/line-break-after-fun-dec.R

@@ -0,0 +1,5 @@
+context("test-mlr-style")
+
+test_that("line break for multi-line function declaration", {
+  test_collection("mlr-style", "line-break")
+})