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Check for Presence of Control Sequences

Source: R/sgr.R
has_ctl.Rd

has_ctl checks for any Control Sequence. You can check for different types of sequences with the ctl parameter. Warnings are only emitted for malformed CSI or OSC sequences.

Usage

has_ctl(x, ctl = "all", warn = getOption("fansi.warn", TRUE), which)

Arguments

x

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

ctl

character, which Control Sequences should be treated specially. 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, and OSC hyperlinks, fansi will also parse, interpret, and reapply the sequences as needed. You can modify whether a Control Sequence is treated specially with the ctl parameter.

  • "nl": newlines.

  • "c0": all other "C0" control characters (i.e. 0x01-0x1f, 0x7F), except for newlines and the actual ESC (0x1B) character.

  • "sgr": ANSI CSI SGR sequences.

  • "csi": all non-SGR ANSI CSI sequences.

  • "url": OSC hyperlinks

  • "osc": all non-OSC-hyperlink OSC sequences.

  • "esc": 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".

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).

which

character, deprecated in favor of ctl.

Value

logical of same length as x; NA values in x result in NA values in return

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

has_ctl("hello world")
#> [1] FALSE
has_ctl("hello\nworld")
#> [1] TRUE
has_ctl("hello\nworld", "sgr")
#> [1] FALSE
has_ctl("hello\033[31mworld\033[m", "sgr")
#> [1] TRUE