ARROW-12869: [R] Bindings for utf8_reverse and ascii_reverse

r/DESCRIPTION

@@ -48,6 +48,7 @@ Suggests:
     pkgload,
     reticulate,
     rmarkdown,
+    stringi,
     stringr,
     testthat,
     tibble,

r/R/expression.R

@@ -30,6 +30,7 @@
   "str_length" = "utf8_length",
   "str_to_lower" = "utf8_lower",
   "str_to_upper" = "utf8_upper",
+  "str_reverse" = "utf8_reverse"
   # str_trim is defined in dplyr-functions.R
   "year" = "year",
   "isoyear" = "iso_year",

r/tests/testthat/test-dplyr-string-functions.R

@@ -20,6 +20,7 @@ skip_if_not_available("utf8proc")
 
 library(dplyr)
 library(stringr)
+library(stringi)
 
 test_that("paste, paste0, and str_c", {
   df <- tibble(
@@ -713,8 +714,6 @@ test_that("strptime", {
     check.tzone = FALSE
   )
 
-})
-
 test_that("errors in strptime", {
   # Error when tz is passed
 
@@ -725,6 +724,43 @@ test_that("errors in strptime", {
   )
 })
 
+test_that("stri_reverse and arrow_ascii_reverse functions", {
+
+  df_ascii <- tibble(x = c("Foo\nand bar", "baz\tand qux and quux"))
+
+  df_utf8 <- tibble(x = c("Foo\u00A0\u0061nd\u00A0bar", "\u0062az\u00A0and\u00A0qux\u3000and\u00A0quux"))
+
+  expect_dplyr_equal(
+    input %>%
+      mutate(x = stri_reverse(x)) %>%
+      collect(),
+    df_utf8
+  )
+
+  expect_dplyr_equal(
+    input %>%
+      mutate(x = stri_reverse(x)) %>%
+      collect(),
+    df_ascii
+  )
+
+  expect_equivalent(
+    df_ascii %>%
+      Table$create() %>%
+      mutate(x = arrow_ascii_reverse(x)) %>%
+      collect(),
+    tibble(x = c("rab dna\nooF", "xuuq dna xuq dna\tzab"))
+  )
+
+  expect_error(
+    df_utf8 %>%
+      Table$create() %>%
+      mutate(x = arrow_ascii_reverse(x)) %>%
+      collect(),
+    "Invalid: Non-ASCII sequence in input"
+  )
+})
+
 test_that("str_like", {
 
   df <- tibble(x = c("Foo and bar", "baz and qux and quux"))
@@ -785,5 +821,4 @@ test_that("str_like", {
       collect(),
     df,
   )
-
 })