strip_ctl: Strip ANSI Control Sequences

Description

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

Usage

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

Arguments

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

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).

strip

character, deprecated in favor of ctl.

Value

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

_ctl vs. _sgr

The *_ctl versions of the functions treat all Control Sequences specially by default. Special treatment is context dependent, and may include detecting them and/or computing their display/character width as zero. For the SGR subset of the ANSI CSI sequences, fansi will also parse, interpret, and reapply the text styles they encode if needed. You can modify whether a Control Sequence is treated specially with the ctl parameter. You can exclude a type of Control Sequence from special treatment by combining "all" with that type of sequence (e.g. ctl=c("all", "nl") for special treatment of all Control Sequences but newlines). The *_sgr versions only treat ANSI CSI SGR sequences specially, and are equivalent to the *_ctl versions with the ctl parameter set to "sgr".

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 option then everything but that option will be stripped.

Examples

Run this code

# NOT RUN {
string <- "hello\033k\033[45p world\n\033[31mgoodbye\a moon"
strip_ctl(string)
strip_ctl(string, c("nl", "c0", "sgr", "csi", "esc")) # equivalently
strip_ctl(string, "sgr")
strip_ctl(string, c("c0", "esc"))

## 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"))

## convenience function, same as `strip_ctl(ctl='sgr')`
strip_sgr(string)
# }

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