parse {base}R Documentation

Parse Expressions


parse returns the parsed but unevaluated expressions in a list.


parse(file = "", n = NULL, text = NULL, prompt = "?", srcfile,
      encoding = "unknown")


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 integer (or coerced to integer). The maximum number of expressions to parse. If n is NULL or negative or NA 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. Other R objects will be coerced to character (without method dispatch) if possible.
prompt the prompt to print when parsing from the keyboard. NULL means to use R's prompt, getOption("prompt").
srcfile NULL, or a srcfile object. See the Details section.
encoding encoding to be assumed for input strings. 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.


If text has length greater than zero (after coercion) it is used in preference to file.

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.

The default for srcfile is set as follows. If options("keep.source") is FALSE, srcfile defaults to NULL. Otherwise, if text is used, srcfile will be set to a srcfilecopy containing the text. If a character string is used for file, a srcfile object referring to that file will be used.


An object of type "expression", with up to n elements if specified as a non-negative integer.
When srcfile is non-NULL, a "srcref" attribute will be attached to the result containing a list of srcref records corresponding to each element.
A syntax error (including an incomplete expression) will throw an error.
Character strings in the result will have a declared encoding if encoding is "latin1" or "UTF-8".


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

scan, source, eval, deparse.


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)

[Package base version 2.5.0 Index]