state_at_end reads through strings computing the accumulated SGR and
OSC hyperlinks, and outputs the active state at the end of them.
close_state produces the sequence that closes any SGR active and OSC
hyperlinks at the end of each input string. If normalize = FALSE
(default), it will emit the reset code "ESC[0m" if any SGR is present.
It is more interesting for closing SGRs if normalize = TRUE. Unlike
state_at_end and other functions close_state has no concept of carry:
it will only emit closing sequences for states explicitly active at the end
of a string.
state_at_end(
x,
warn = getOption("fansi.warn", TRUE),
term.cap = getOption("fansi.term.cap", dflt_term_cap()),
normalize = getOption("fansi.normalize", FALSE),
carry = getOption("fansi.carry", FALSE)
)close_state(
x,
warn = getOption("fansi.warn", TRUE),
normalize = getOption("fansi.normalize", FALSE)
)
character vector same length as x.
a character vector or object that can be coerced to such.
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).
character a vector of the capabilities of the terminal, can
be any combination of "bright" (SGR codes 90-97, 100-107), "256" (SGR codes
starting with "38;5" or "48;5"), "truecolor" (SGR codes starting with
"38;2" or "48;2"), and "all". "all" behaves as it does for the ctl
parameter: "all" combined with any other value means all terminal
capabilities except that one. fansi will warn if it encounters SGR codes
that exceed the terminal capabilities specified (see term_cap_test
for details). In versions prior to 1.0, fansi would also skip exceeding
SGRs entirely instead of interpreting them. You may add the string "old"
to any otherwise valid term.cap spec to restore the pre 1.0 behavior.
"old" will not interact with "all" the way other valid values for this
parameter do.
TRUE or FALSE (default) whether SGR sequence should be
normalized out such that there is one distinct sequence for each SGR code.
normalized strings will occupy more space (e.g. "\033[31;42m" becomes
"\033[31m\033[42m"), but will work better with code that assumes each SGR
code will be in its own escape as crayon does.
TRUE, FALSE (default), or a scalar string, controls whether to
interpret the character vector as a "single document" (TRUE or string) or
as independent elements (FALSE). In "single document" mode, active state
at the end of an input element is considered active at the beginning of the
next vector element, simulating what happens with a document with active
state at the end of a line. If FALSE each vector element is interpreted as
if there were no active state when it begins. If character, then the
active state at the end of the carry string is carried into the first
element of x (see "Replacement Functions" for differences there). The
carried state is injected in the interstice between an imaginary zeroeth
character and the first character of a vector element. See the "Position
Semantics" section of substr_ctl and the "State Interactions" section
of ?fansi for details. Except for strwrap_ctl where NA is
treated as the string "NA", carry will cause NAs in inputs to
propagate through the remaining vector elements.
Control Sequences are non-printing characters or sequences of characters.
Special Sequences are a subset of the Control Sequences, and include CSI
SGR sequences which can be used to change rendered appearance of text, and
OSC hyperlinks. See fansi for details.
Several factors could affect the exact output produced by fansi
functions across versions of fansi, R, and/or across systems.
In general it is best not to rely on exact fansi output, e.g. by
embedding it in tests.
Width and grapheme calculations depend on locale, Unicode database
version, and grapheme processing logic (which is still in development), among
other things. For the most part fansi (currently) uses the internals of
base::nchar(type='width'), but there are exceptions and this may change in
the future.
How a particular display format is encoded in Control Sequences is
not guaranteed to be stable across fansi versions. Additionally, which
Special Sequences are re-encoded vs transcribed untouched may change.
In general we will strive to keep the rendered appearance stable.
To maximize the odds of getting stable output set normalize_state to
TRUE and type to "chars" in functions that allow it, and
set term.cap to a specific set of capabilities.
?fansi for details on how Control Sequences are
interpreted, particularly if you are getting unexpected results,
unhandled_ctl for detecting bad control sequences.
x <- c("\033[44mhello", "\033[33mworld")
state_at_end(x)
state_at_end(x, carry=TRUE)
(close <- close_state(state_at_end(x, carry=TRUE), normalize=TRUE))
writeLines(paste0(x, close, " no style"))
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