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#' Convert string to upper case, lower case, title case, or sentence 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.
#'
#' @inheritParams str_detect
#' @inheritParams coll
#' @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")
#'
#' # Locale matters!
#' str_to_upper("i") # English
#' str_to_upper("i", "tr") # Turkish
#' @name case
NULL
#' @export
#' @rdname case
str_to_upper <- function(string, locale = "en") {
check_string(locale)
copy_names(string, stri_trans_toupper(string, locale = locale))
}
#' @export
#' @rdname case
str_to_lower <- function(string, locale = "en") {
check_string(locale)
copy_names(string, stri_trans_tolower(string, locale = locale))
}
#' @export
#' @rdname case
str_to_title <- function(string, locale = "en") {
check_string(locale)
out <- stri_trans_totitle(
string,
opts_brkiter = stri_opts_brkiter(locale = locale)
)
copy_names(string, out)
}
#' @export
#' @rdname case
str_to_sentence <- function(string, locale = "en") {
check_string(locale)
out <- stri_trans_totitle(
string,
opts_brkiter = stri_opts_brkiter(type = "sentence", locale = locale)
)
copy_names(string, out)
}
#' Convert between different types of programming case
#'
#' @description
#' * `str_to_camel()` converts to camel case, where the first letter of
#' each word is capitalized, with no separation between words. By default
#' the first letter of the first word is not capitalized.
#'
#' * `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_to_lower
#' @export
#' @param first_upper Logical. Should the first letter be capitalized?
#' @examples
#' str_to_camel("my-variable")
#' str_to_camel("my-variable", first_upper = TRUE)
#'
#' str_to_snake("MyVariable")
#' str_to_kebab("MyVariable")
str_to_camel <- function(string, first_upper = FALSE) {
check_character(string)
check_bool(first_upper)
string <- string |>
to_words() |>
str_to_title() |>
str_remove_all(pattern = fixed(" "))
if (!first_upper) {
str_sub(string, 1, 1) <- str_to_lower(str_sub(string, 1, 1))
}
string
}
#' @export
#' @rdname str_to_camel
str_to_snake <- function(string) {
check_character(string)
to_separated_case(string, sep = "_")
}
#' @export
#' @rdname str_to_camel
str_to_kebab <- function(string) {
check_character(string)
to_separated_case(string, sep = "-")
}
to_separated_case <- function(string, sep) {
out <- to_words(string)
str_replace_all(out, fixed(" "), sep)
}
to_words <- function(string) {
breakpoints <- paste(
# non-word characters
"[^\\p{L}\\p{N}]+",
# lowercase followed by uppercase
"(?<=\\p{Ll})(?=\\p{Lu})",
# letter followed by number
"(?<=\\p{L})(?=\\p{N})",
# number followed by letter
"(?<=\\p{N})(?=\\p{L})",
# uppercase followed uppercase then lowercase (i.e. end of acronym)
"(?<=\\p{Lu})(?=\\p{Lu}\\p{Ll})",
sep = "|"
)
out <- str_replace_all(string, breakpoints, " ")
out <- str_to_lower(out)
str_trim(out)
}
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