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Strip Control Sequences

Source: R/sgr.R
strip_ctl.Rd

Removes Control Sequences from strings. By default it will strip all known Control Sequences, including CSI/OSC sequences, two character sequences starting with ESC, and all C0 control characters, including newlines. You can fine tune this behavior with the ctl parameter.

Usage

strip_ctl(x, ctl = "all", warn = getOption("fansi.warn", TRUE), strip)

Arguments

x

a character vector or object that can be coerced to such.

ctl

character, any combination of the following values (see details):

  • "nl": strip newlines.

  • "c0": strip all other "C0" control characters (i.e. x01-x1f, x7F), except for newlines and the actual ESC character.

  • "sgr": strip ANSI CSI SGR sequences.

  • "csi": strip all non-SGR csi sequences.

  • "esc": strip all other escape sequences.

  • "all": all of the above, except when used in combination with any of the above, in which case it means "all but" (see details).

warn

TRUE (default) or FALSE, whether to warn when potentially problematic Control Sequences are encountered. These could cause the assumptions fansi makes about how strings are rendered on your display to be incorrect, for example by moving the cursor (see ?fansi). At most one warning will be issued per element in each input vector. Will also warn about some badly encoded UTF-8 strings, but a lack of UTF-8 warnings is not a guarantee of correct encoding (use validUTF8 for that).

strip

character, deprecated in favor of ctl.

Value

character vector of same length as x with ANSI escape sequences stripped

Details

The ctl value contains the names of non-overlapping subsets of the known Control Sequences (e.g. "csi" does not contain "sgr", and "c0" does not contain newlines). The one exception is "all" which means strip every known sequence. If you combine "all" with any other options then everything but those options will be stripped.

Note

Non-ASCII strings are converted to and returned in UTF-8 encoding.

See also

?fansi for details on how Control Sequences are interpreted, particularly if you are getting unexpected results, unhandled_ctl for detecting bad control sequences.

Examples

string <- "hello\033k\033[45p world\n\033[31mgoodbye\a moon"
strip_ctl(string)
#> [1] "hello worldgoodbye moon"
strip_ctl(string, c("nl", "c0", "sgr", "csi", "esc")) # equivalently
#> [1] "hello worldgoodbye moon"
strip_ctl(string, "sgr")
#> [1] "hello\033k\033[45p world\ngoodbye\a moon"
strip_ctl(string, c("c0", "esc"))
#> [1] "hello45p world\n31mgoodbye moon"

## everything but C0 controls, we need to specify "nl"
## in addition to "c0" since "nl" is not part of "c0"
## as far as the `strip` argument is concerned
strip_ctl(string, c("all", "nl", "c0"))
#> [1] "hello world\ngoodbye\a moon"