hdx.sockconn: Half-duplex socket communication

In royratcliffe/canny.tudor: What the Package Does (One Line, Title Case)

Half-duplex socket communication

Description

Writes then reads a socket connection.

Usage

## S3 method for class 'sockconn'
hdx(x, text, write.sep = "\n", write.useBytes = FALSE, timeout = NULL, ...)

Arguments

x	Socket connection.
text	Lines of text to write to the socket connection, a character vector. Writes all the lines before reading.
write.sep	Line separator written after every line of text, a character string defaulting to a single new-line character "\n".
write.useBytes	Suppresses re-encoding of marked strings.
timeout	Seconds to wait for ready socket, a numeric; or wait indefinitely, NULL.
...	Arguments passed on to base::scan file the name of a file to read data values from. If the specified file is "", then input is taken from the keyboard (or whatever stdin() reads if input is redirected or R is embedded). (In this case input can be terminated by a blank line or an EOF signal, Ctrl-D on Unix and Ctrl-Z on Windows.) Otherwise, the file name is interpreted relative to the current working directory (given by getwd()), unless it specifies an absolute path. Tilde-expansion is performed where supported. When running R from a script, file = "stdin" can be used to refer to the process's stdin file stream. This can be a compressed file (see file). Alternatively, file can be a connection, which will be opened if necessary, and if so closed at the end of the function call. Whatever mode the connection is opened in, any of LF, CRLF or CR will be accepted as the EOL marker for a line and so will match sep = "\n". file can also be a complete URL. (For the supported URL schemes, see the ‘URLs’ section of the help for url.) To read a data file not in the current encoding (for example a Latin-1 file in a UTF-8 locale or conversely) use a file connection setting its encoding argument (or scan's fileEncoding argument). what the type of what gives the type of data to be read. (Here ‘type’ is used in the sense of typeof.) The supported types are logical, integer, numeric, complex, character, raw and list. If what is a list, it is assumed that the lines of the data file are records each containing length(what) items (‘fields’) and the list components should have elements which are one of the first six (atomic) types listed or NULL, see section ‘Details’ below. nmax the maximum number of data values to be read, or if what is a list, the maximum number of records to be read. If omitted or not positive or an invalid value for an integer (and nlines is not set to a positive value), scan will read to the end of file. n integer: the maximum number of data values to be read, defaulting to no limit. Invalid values will be ignored. sep by default, scan expects to read ‘white-space’ delimited input fields. Alternatively, sep can be used to specify a character which delimits fields. A field is always delimited by an end-of-line marker unless it is quoted. If specified this should be the empty character string (the default) or NULL or a character string containing just one single-byte character. quote the set of quoting characters as a single character string or NULL. In a multibyte locale the quoting characters must be ASCII (single-byte). dec decimal point character. This should be a character string containing just one single-byte character. (NULL and a zero-length character vector are also accepted, and taken as the default.) skip the number of lines of the input file to skip before beginning to read data values. nlines if positive, the maximum number of lines of data to be read. na.strings character vector. Elements of this vector are to be interpreted as missing (NA) values. Blank fields are also considered to be missing values in logical, integer, numeric and complex fields. Note that the test happens after white space is stripped from the input, so na.strings values may need their own white space stripped in advance. flush logical: if TRUE, scan will flush to the end of the line after reading the last of the fields requested. This allows putting comments after the last field, but precludes putting more that one record on a line. fill logical: if TRUE, scan will implicitly add empty fields to any lines with fewer fields than implied by what. strip.white vector of logical value(s) corresponding to items in the what argument. It is used only when sep has been specified, and allows the stripping of leading and trailing ‘white space’ from character fields (numeric fields are always stripped). Note: white space inside quoted strings is not stripped. If strip.white is of length 1, it applies to all fields; otherwise, if strip.white[i] is TRUE and the i-th field is of mode character (because what[i] is) then the leading and trailing unquoted white space from field i is stripped. quiet logical: if FALSE (default), scan() will print a line, saying how many items have been read. blank.lines.skip logical: if TRUE blank lines in the input are ignored, except when counting skip and nlines. multi.line logical. Only used if what is a list. If FALSE, all of a record must appear on one line (but more than one record can appear on a single line). Note that using fill = TRUE implies that a record will be terminated at the end of a line. comment.char character: a character vector of length one containing a single character or an empty string. Use "" to turn off the interpretation of comments altogether (the default). allowEscapes logical. Should C-style escapes such as \n be processed (the default) or read verbatim? Note that if not within quotes these could be interpreted as a delimiter (but not as a comment character). The escapes which are interpreted are the control characters \a, \b, \f, \n, \r, \t, \v and octal and hexadecimal representations like \040 and \0x2A. Any other escaped character is treated as itself, including backslash. Note that Unicode escapes (starting \u or \U: see Quotes) are never processed. fileEncoding character string: if non-empty declares the encoding used on a file (not a connection nor the keyboard) so the character data can be re-encoded. See the ‘Encoding’ section of the help for file, and the ‘R Data Import/Export Manual’. encoding encoding to be assumed for input strings. If the value is "latin1" or "UTF-8" it is used to mark character strings as known to be in Latin-1 or UTF-8: it is not used to re-encode the input (see fileEncoding). See also ‘Details’. skipNul logical: should nuls be skipped when reading character fields?

Details

The second half of the half-duplex communication, the scan half, terminates on remote buffer flush, not necessarily on a line termination. Typically the server side socket will automatically flush when it sees a line terminator. It could however flush for other reasons, in which case the scan will complete.

Examples

## Not run: 
hdx(con, c("hello", "world"), what = character())

## End(Not run)

royratcliffe/canny.tudor documentation built on Oct. 17, 2022, 4:17 a.m.