strwrap_ctl

0th

Percentile

ANSI Control Sequence Aware Version of strwrap

Wraps strings to a specified width accounting for zero display width Control Sequences. strwrap_ctl is intended to emulate strwrap exactly except with respect to the Control Sequences, while strwrap2_ctl adds features and changes the processing of whitespace.

Usage
strwrap_ctl(x, width = 0.9 * getOption("width"), indent = 0,
  exdent = 0, prefix = "", simplify = TRUE, initial = prefix,
  warn = getOption("fansi.warn"),
  term.cap = getOption("fansi.term.cap"), ctl = "all")

strwrap2_ctl(x, width = 0.9 * getOption("width"), indent = 0, exdent = 0, prefix = "", simplify = TRUE, initial = prefix, wrap.always = FALSE, pad.end = "", strip.spaces = !tabs.as.spaces, tabs.as.spaces = getOption("fansi.tabs.as.spaces"), tab.stops = getOption("fansi.tab.stops"), warn = getOption("fansi.warn"), term.cap = getOption("fansi.term.cap"), ctl = "all")

strwrap_sgr(x, width = 0.9 * getOption("width"), indent = 0, exdent = 0, prefix = "", simplify = TRUE, initial = prefix, warn = getOption("fansi.warn"), term.cap = getOption("fansi.term.cap"))

strwrap2_sgr(x, width = 0.9 * getOption("width"), indent = 0, exdent = 0, prefix = "", simplify = TRUE, initial = prefix, wrap.always = FALSE, pad.end = "", strip.spaces = !tabs.as.spaces, tabs.as.spaces = getOption("fansi.tabs.as.spaces"), tab.stops = getOption("fansi.tab.stops"), warn = getOption("fansi.warn"), term.cap = getOption("fansi.term.cap"))

Arguments
x

a character vector, or an object which can be converted to a character vector by as.character.

width

a positive integer giving the target column for wrapping lines in the output.

indent

a non-negative integer giving the indentation of the first line in a paragraph.

exdent

a non-negative integer specifying the indentation of subsequent lines in paragraphs.

prefix

a character string to be used as prefix for each line except the first, for which initial is used.

simplify

a logical. If TRUE, the result is a single character vector of line text; otherwise, it is a list of the same length as x the elements of which are character vectors of line text obtained from the corresponding element of x. (Hence, the result in the former case is obtained by unlisting that of the latter.)

initial

a character string to be used as prefix for each line except the first, for which initial is used.

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).

term.cap

character a vector of the capabilities of the terminal, can be any combination "bright" (SGR codes 90-97, 100-107), "256" (SGR codes starting with "38;5" or "48;5"), and "truecolor" (SGR codes starting with "38;2" or "48;2"). Changing this parameter changes how fansi interprets escape sequences, so you should ensure that it matches your terminal capabilities. See term_cap_test for details.

ctl

character, which Control Sequences should be treated specially. See the "_ctl vs. _sgr" section for details.

  • "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.

  • "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".

wrap.always

TRUE or FALSE (default), whether to hard wrap at requested width if no word breaks are detected within a line. If set to TRUE then width must be at least 2.

pad.end

character(1L), a single character to use as padding at the end of each line until the line is width wide. This must be a printable ASCII character or an empty string (default). If you set it to an empty string the line remains unpadded.

strip.spaces

TRUE (default) or FALSE, if TRUE, extraneous white spaces (spaces, newlines, tabs) are removed in the same way as base::strwrap does. When FALSE, whitespaces are preserved, except for newlines as those are implicit in boundaries between vector elements.

tabs.as.spaces

FALSE (default) or TRUE, whether to convert tabs to spaces. This can only be set to TRUE if strip.spaces is FALSE.

tab.stops

integer(1:n) indicating position of tab stops to use when converting tabs to spaces. If there are more tabs in a line than defined tab stops the last tab stop is re-used. For the purposes of applying tab stops, each input line is considered a line and the character count begins from the beginning of the input line.

Details

strwrap2_ctl can convert tabs to spaces, pad strings up to width, and hard-break words if single words are wider than width.

Unlike base::strwrap, both these functions will translate any non-ASCII strings to UTF-8 and return them in UTF-8. Additionally, malformed UTF-8 sequences are not converted to a text representation of bytes.

When replacing tabs with spaces the tabs are computed relative to the beginning of the input line, not the most recent wrap point. Additionally,indent, exdent, initial, and prefix will be ignored when computing tab positions.

Note

Non-ASCII strings are converted to and returned in UTF-8 encoding. Width calculations will not work correctly with R < 3.2.2.

_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".

See Also

fansi for details on how Control Sequences are interpreted, particularly if you are getting unexpected results.

Aliases
  • strwrap_ctl
  • strwrap2_ctl
  • strwrap_sgr
  • strwrap2_sgr
Examples
# NOT RUN {
hello.1 <- "hello \033[41mred\033[49m world"
hello.2 <- "hello\t\033[41mred\033[49m\tworld"

strwrap_ctl(hello.1, 12)
strwrap_ctl(hello.2, 12)

## In default mode strwrap2_ctl is the same as strwrap_ctl
strwrap2_ctl(hello.2, 12)

## But you can leave whitespace unchanged, `warn`
## set to false as otherwise tabs causes warning
strwrap2_ctl(hello.2, 12, strip.spaces=FALSE, warn=FALSE)

## And convert tabs to spaces
strwrap2_ctl(hello.2, 12, tabs.as.spaces=TRUE)

## If your display has 8 wide tab stops the following two
## outputs should look the same
writeLines(strwrap2_ctl(hello.2, 80, tabs.as.spaces=TRUE))
writeLines(hello.2)

## tab stops are NOT auto-detected, but you may provide
## your own
strwrap2_ctl(hello.2, 12, tabs.as.spaces=TRUE, tab.stops=c(6, 12))

## You can also force padding at the end to equal width
writeLines(strwrap2_ctl("hello how are you today", 10, pad.end="."))

## And a more involved example where we read the
## NEWS file, color it line by line, wrap it to
## 25 width and display some of it in 3 columns
## (works best on displays that support 256 color
## SGR sequences)

NEWS <- readLines(file.path(R.home('doc'), 'NEWS'))
NEWS.C <- fansi_lines(NEWS, step=2)  # color each line
W <- strwrap2_ctl(NEWS.C, 25, pad.end=" ", wrap.always=TRUE)
writeLines(c("", paste(W[1:20], W[100:120], W[200:220]), ""))
# }
Documentation reproduced from package fansi, version 0.4.0, License: GPL (>= 2)

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