dispatch cases where \ has different meaning.

R/rules-replacement.R

@@ -15,3 +15,54 @@ resolve_semicolon <- function(pd) {
   pd <- pd[!is_semicolon, ]
   pd
 }
+
+
+#' Replace single quotes with double quotes
+#'
+#' @details
+#' Depending on whether the backslash represents a character on its own or
+#' whether it is used to create a special character, we either use:
+#'
+#' - `deparse(parse_text(...))`
+#' - `paste("\"", parse_text(...), "\""))`
+#'
+#' To make sure esaping is done correctly.
+#' @examples
+#' charToRaw("\n") # one character
+#' charToRaw("\\n") # two characters
+#' charToRaw("\\\n") # two characters
+#' # put these into a file and style with style_file(),
+#' # style_text() escapes backslash.
+#' 'here
+#' is a string
+#' '
+#' 'here\nis a string
+#' '
+#' 'here\\nis a string'
+#' @importFrom purrr map map_chr
+#' @param pd_flat A flat parse table.
+#' @keywords internal
+fix_quotes <- function(pd_flat) {
+  str_const <- pd_flat$token == "STR_CONST"
+  str_const_change <- grepl("^'([^\"]*)'$", pd_flat$text[str_const])
+  pd_flat$text[str_const][str_const_change] <- map_chr(
+    pd_flat$text[str_const][str_const_change], fix_quotes_one
+  )
+  pd_flat
+}
+
+fix_quotes_one <- function(x) {
+  one <- has_one_backslash(x)
+  multiple <- has_multiple_backslashes(x)
+
+  if (one && multiple) {
+    x
+  } else if (one) {
+    x %>%
+      parse_text() %>%
+      paste0("\"", ., "\"")
+  } else {
+    parse_text(x) %>%
+      deparse()
+  }
+}

R/rules-spacing.R

@@ -115,27 +115,6 @@ remove_space_after_unary_pm_nested <- function(pd) {
   pd
 }
 
-#' Replace single quotes with double quotes
-#'
-#' We do not use `deparse()` as in previous implementations but `paste0()` since
-#' the former approach escapes the reverse backslash in the line break character
-#' `\\n` whereas the solution with `paste0()` does not.
-#' @examples
-#' style_text("'here
-#' is a string
-#' '")
-#' @importFrom purrr map map_chr
-#' @param pd_flat A flat parse table.
-#' @keywords internal
-fix_quotes <- function(pd_flat) {
-  str_const <- pd_flat$token == "STR_CONST"
-  str_const_change <- grepl("^'([^\"]*)'$", pd_flat$text[str_const])
-  pd_flat$text[str_const][str_const_change] <-
-    map(pd_flat$text[str_const][str_const_change], parse_text) %>%
-    map_chr(~ paste0("\"", .x, "\""))
-  pd_flat
-}
-
 remove_space_before_opening_paren <- function(pd_flat) {
   paren_after <- pd_flat$token == "'('"
   if (!any(paren_after)) {

R/utils-strings.R

@@ -27,3 +27,21 @@ add_newlines <- function(n) {
 add_spaces <- function(n) {
   rep_char(" ", n)
 }
+
+
+has_one_backslash <- function(x) {
+  x <- char2raw_as_char(x)
+  any(substr(x, 1, 1) == "0")
+}
+
+has_multiple_backslashes <- function(x) {
+  x <- char2raw_as_char(x)
+  any(x == "5c")
+}
+
+char2raw_as_char <- function(x) {
+  x <- charToRaw(x)
+  class(x) <- "character"
+  x
+}
+

tests/testthat/escaping/basic-escape-in.R

@@ -22,6 +22,19 @@ NULL
 #' things
 #'
 #' @examples
-#' call('\n') # FIXME when single quotes are used, the newline is evaluated
+#' call('\n') # fixed: when single quotes are used, the newline is evaluated
 #' ano("\\.", further = X)
 NULL
+
+'single quotes with
+embedded and \n not embedded line breaks will not be replaced
+with \\n double quotes. Too hard sorry.' #FIXME
+
+
+x <- '	2' # there is a tab emebbed (created with writeLines("x <- '\t2'"))
+
+x <- '\001'
+'\x01'
+
+# FIXME: "\01" gives an error when not in a comment
+# FIXME: this too: '\01'

tests/testthat/escaping/basic-escape-out.R

@@ -22,7 +22,19 @@ NULL
 #' things
 #'
 #' @examples
-#' call("
-#' ") # FIXME when single quotes are used, the newline is evaluated
+#' call("\n") # fixed: when single quotes are used, the newline is evaluated
 #' ano("\\.", further = X)
 NULL
+
+'single quotes with
+embedded and \n not embedded line breaks will not be replaced
+with \\n double quotes. Too hard sorry.' # FIXME
+
+
+x <- "	2" # there is a tab emebbed (created with writeLines("x <- '\t2'"))
+
+x <- "\001"
+"\001"
+
+# FIXME: "\01" gives an error when not in a comment
+# '\01'

tests/testthat/strict/non_strict-in.R

@@ -13,7 +13,7 @@ test <- function() {
   single quotes are used
   .'
 
-  'strings with embeded\nline breaks are unfortunately split'
+  'strings with embeded\nline breaks are no longer split'
 
   # Comments are always preserved
 

tests/testthat/strict/non_strict-out.R

@@ -13,8 +13,7 @@ test <- function() {
   single quotes are used
   ."
 
-  "strings with embeded
-line breaks are unfortunately split"
+  "strings with embeded\nline breaks are no longer split"
 
   # Comments are always preserved
 

tests/testthat/test-utils.R

@@ -18,3 +18,14 @@ test_that("files with and without blank EOF line are read correctly", {
     test_path("reference-objects/return-read-utf8-non-missing-EOF")
   )
 })
+
+
+test_that("escape characters are properly recognized", {
+  one <- "jlkaf\n"
+  multiple <- "\\n3"
+  expect_true(has_one_backslash(one))
+  expect_false(has_one_backslash(multiple))
+  expect_false(has_multiple_backslashes(one))
+  expect_true(has_multiple_backslashes(multiple))
+
+})