parse {base} | R Documentation |
parse
returns the parsed but unevaluated expressions in a
list. Each element of the list is of mode expression
.
parse(file = "", n = NULL, text = NULL, prompt = "?")
file |
a connection, or a character string giving the name of a
file or a URL to read the expressions from.
If file is "" and text is missing or NULL
then input is taken from the console. |
n |
the maximum number of expressions to parse. If n is
NULL or negative the input is parsed in its entirety. |
text |
character vector. The text to parse. Elements are treated as if they were lines of a file. |
prompt |
the prompt to print when parsing from the keyboard.
NULL means to use R's prompt, getOption("prompt") . |
All versions of R accept input from a connection with end of line marked by LF (as used on Unix), CRLF (as used on DOS/Windows) or CR (as used on classic MacOS). The final line can be incomplete, that is missing the final EOL marker.
See source
for the limits on the size of functions
that can be parsed (by default). There is also a limit of 8192 bytes
on the size of strings which can be parsed.
When input is taken from the console, n = NULL
is equivalent to
n = 1
, and n < 0
will read until an EOF character is read.
An object of type "expression"
, with up to n
elements if specified as a non-negative integer.
A syntax error (including an incomplete expression) will throw an error.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
cat("x <- c(1,4)\n x ^ 3 -10 ; outer(1:7,5:9)\n", file="xyz.Rdmped") # parse 3 statements from the file "xyz.Rdmped" parse(file = "xyz.Rdmped", n = 3) unlink("xyz.Rdmped")