Add functions: str_to_pascal(), str_to_camel(), str_to_kebab(), str_to_snake()

NAMESPACE

@@ -12,11 +12,13 @@ S3method(type,stringr_fixed)
 S3method(type,stringr_regex)
 export("%>%")
 export("str_sub<-")
+export(StrToPascal)
 export(boundary)
 export(coll)
 export(fixed)
 export(invert_match)
 export(regex)
+export(strToCamel)
 export(str_c)
 export(str_conv)
 export(str_count)
@@ -57,8 +59,12 @@ export(str_starts)
 export(str_sub)
 export(str_sub_all)
 export(str_subset)
+export(str_to_camel)
+export(str_to_kebab)
 export(str_to_lower)
+export(str_to_pascal)
 export(str_to_sentence)
+export(str_to_snake)
 export(str_to_title)
 export(str_to_upper)
 export(str_trim)

R/case.R

@@ -1,21 +1,41 @@
-#' Convert string to upper case, lower case, title case, or sentence case
+#' Convert string to upper case, lower case, title case, sentence case, pascal
+#' case, camel case, kebab case, or snake case
 #'
 #' * `str_to_upper()` converts to upper case.
 #' * `str_to_lower()` converts to lower case.
 #' * `str_to_title()` converts to title case, where only the first letter of
 #'   each word is capitalized.
 #' * `str_to_sentence()` convert to sentence case, where only the first letter
 #'   of sentence is capitalized.
+#' * `str_to_pascal()` converts to pascal case, where only the first letter of
+#'   each word is capitalized, with no separation between
+#'   words.
+#' * `str_to_pascal()` and `StrToPascal()` are synonyms
+#' * `str_to_camel()` converts to camel case, where only the first letter of
+#'   each word after the first word is capitalized, with no separation between
+#'   words.
+#' * `str_to_camel()` and `strToCamel()` are synonyms
+#' * `str_to_kebab()` converts to kebab case, where words are converted to
+#'   lower case and separated by dashes (`-`).
+#' * `str_to_snake()` converts to snake case, where words are converted to
+#'   lower case and separated by underscores (`_`).
 #'
 #' @inheritParams str_detect
 #' @inheritParams coll
+#' @param separator string. For snake case, can change the `_`
 #' @return A character vector the same length as `string`.
 #' @examples
 #' dog <- "The quick brown dog"
 #' str_to_upper(dog)
 #' str_to_lower(dog)
 #' str_to_title(dog)
 #' str_to_sentence("the quick brown dog")
+#' str_to_pascal(dog)
+#' StrToPascal(dog)
+#' str_to_camel(dog)
+#' strToCamel(dog)
+#' str_to_kebab(dog)
+#' str_to_snake(dog)
 #'
 #' # Locale matters!
 #' str_to_upper("i") # English
@@ -54,3 +74,50 @@ str_to_sentence <- function(string, locale = "en") {
     opts_brkiter = stri_opts_brkiter(type = "sentence", locale = locale)
   )
 }
+#' @export
+#' @rdname case
+str_to_pascal <- function(string, locale = "en") {
+  stopifnot(is.character(string))
+  string <- string |>
+    str_replace_all("([a-z])([A-Z])", "\\1 \\2") |>
+    str_replace_all("([0-9])([a-zA-Z])", "\\1 \\2") |>
+    str_replace_all("([A-Z]+)([A-Z][a-z])", "\\1 \\2") |>
+    str_replace_all(pattern = "[:punct:]", replace = " ") |>
+    str_to_title(locale = locale) |>
+    str_remove_all(pattern = "\\s+")
+  return(string)
+}
+#' @export
+#' @rdname case
+StrToPascal <- str_to_pascal
+#' @export
+#' @rdname case
+str_to_camel <- function(string, locale = "en") {
+  string <- str_to_pascal(string, locale = locale)
+  string <- str_replace(string, pattern = "^.", replace = str_to_lower(str_sub(string, 1, 1)))
+  return(string)
+}
+#' @export
+#' @rdname case
+strToCamel <- str_to_camel
+#' @export
+#' @rdname case
+str_to_snake <- function(string, separator = "_", locale = "en") {
+  stopifnot(is.character(string))
+  string <- string |>
+    str_replace_all("([a-z])([A-Z])", "\\1 \\2") |>
+    str_replace_all("([a-zA-Z])([0-9])", "\\1 \\2") |>
+    str_replace_all("([0-9])([a-zA-Z])", "\\1 \\2") |>
+    str_replace_all("([A-Z]+)([A-Z][a-z])", "\\1 \\2") |>
+    str_to_lower(locale = locale) |>
+    str_replace_all(pattern = "[:punct:]", replace = " ") |>
+    str_trim() |>
+    str_replace_all(pattern = "\\s+", replace = separator)
+  return(string)
+}
+#' @export
+#' @rdname case
+str_to_kebab <- function(string, locale = "en") {
+  string <- str_to_snake(string, separator = "-", locale = locale)
+  return(string)
+}

tests/testthat/test-case.R

@@ -10,6 +10,25 @@ test_that("to_title creates one capital letter per word", {
 })
 
 test_that("to_sentence capitalizes just the first letter", {
-  x <- "This is a sentence."
   expect_identical(str_to_sentence("a Test"), "A test")
 })
+
+test_that("to_pascal converts to pascal case", {
+  expect_identical(str_to_pascal("This is a sentence."), "ThisIsASentence")
+})
+
+test_that("to_camel converts to camel casee", {
+  expect_identical(str_to_camel("This is a sentence."), "thisIsASentence")
+})
+
+test_that("to_kebab converts to kebab case", {
+  expect_identical(str_to_kebab("This is a sentence."), "this-is-a-sentence")
+})
+
+test_that("to_snake converts to snake case", {
+  expect_identical(str_to_snake("This is a sentence."), "this_is_a_sentence")
+})
+
+test_that("to_snake converts to snake case", {
+  expect_identical(str_to_snake("This is a sentence.", separator = "!"), "this!is!a!sentence")
+})

vignettes/stringr.Rmd

@@ -129,6 +129,7 @@ A handful of stringr functions are locale-sensitive: they will perform different
 x <- "I like horses."
 str_to_upper(x)
 str_to_title(x)
+str_to_snake(x) # case transformation for programming
 
 str_to_lower(x)
 # Turkish has two sorts of i: with and without the dot