R/altrep_backend-escape.R

In charr: String Processing Reimagined for 'ALTREP' Strings

# Copied from stringi; stri_* renamed to ci_*.
# kate: default-dictionary en_US

## This file is part of the 'stringi' package for R.
## Copyright (c) 2013-2025, Marek Gagolewski <https://www.gagolewski.com/>
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# @title
# Escape Unicode Code Points
#
# @description
# Generates an ASCII string where all non-printable characters
# and non-ASCII characters are converted to escape sequences.
#
# @details
#
# For non-printable and certain special (well-known,
# see also the R man page \link{Quotes})
# ASCII characters, the following
# (also recognized in R) convention is used.
# We get \code{\\a}, \code{\\b}, \code{\\t}, \code{\\n}, \code{\\v},
# \code{\\f}, \code{\\r}, \code{\"}, \code{\'}, \code{\\\\}
# or either \code{\\uXXXX} (4 hex digits) or \code{\\UXXXXXXXX} (8 hex digits)
# otherwise.
#
#
# As usual in stringi, any input string is converted to Unicode
# before executing the escape process.
#
#
# @param str character vector
#
# @return
# Returns a character vector.
#
# @examples
# ci_escape_unicode('a\u0105!')
#
# @family escape
# @export
ci_escape_unicode <- function(str)
{
    .Call(C_ci_escape_unicode, str)
}


# @title
# Un-escape All Escape Sequences
#
# @description
# Un-escapes all known escape sequences.
#
# @details
# Uses \pkg{ICU}'s facilities to un-escape Unicode character sequences.
#
# The following escape sequences are recognized:
# \code{\\a}, \code{\\b}, \code{\\t}, \code{\\n}, \code{\\v}, \code{\\?},
# \code{\\e}, \code{\\f}, \code{\\r}, \code{\"}, \code{\'}, \code{\\\\},
# \code{\\uXXXX} (4 hex digits),
# \code{\\UXXXXXXXX} (8 hex digits),
# \code{\\xXX} (1-2 hex digits),
# \code{\\ooo} (1-3 octal digits),
# \code{\\cX} (control-X; X is masked with 0x1F).
# For \code{\\xXX} and \code{\\ooo}, beware of non-valid UTF-8 byte sequences.
#
# Note that some versions of R on Windows cannot handle
# characters defined with \code{\\UXXXXXXXX}.
#
# @param str character vector
#
# @return
# Returns a character vector.
# If an escape sequence is ill-formed,
# the result will be \code{NA} and a warning will be given.
#
# @examples
# ci_unescape_unicode('a\\u0105!\\u0032\\n')
#
# @family escape
# @export