\HeaderA{parse}{Parse Expressions}{parse}
\keyword{file}{parse}
\keyword{programming}{parse}
\keyword{connection}{parse}
\begin{Description}\relax
\code{parse} returns the parsed but unevaluated expressions in a
list.
\end{Description}
\begin{Usage}
\begin{verbatim}
parse(file = "", n = NULL, text = NULL, prompt = "?")
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{file}] a connection, or a character string giving the name of a
file or a URL to read the expressions from.
If \code{file} is \code{""} and \code{text} is missing or \code{NULL}
then input is taken from the console.
\item[\code{n}] integer (or coerced to integer).  The maximum number of
expressions to parse.  If \code{n} is \code{NULL} or negative or
\code{NA} the input is parsed in its entirety.
\item[\code{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.
\item[\code{prompt}] the prompt to print when parsing from the keyboard.
\code{NULL} means to use \R's prompt, \code{getOption("prompt")}.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If \code{text} has length greater than zero (after coercion) it is used in
preference to \code{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 \code{\LinkA{source}{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, \code{n = NULL} is equivalent to
\code{n = 1}, and \code{n < 0} will read until an EOF character is read.
\end{Details}
\begin{Value}
An object of type \code{"\LinkA{expression}{expression}"}, with up to \code{n}
elements if specified as a non-negative integer.

A syntax error (including an incomplete expression) will throw an error.
\end{Value}
\begin{References}\relax
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
\emph{The New S Language}.
Wadsworth \& Brooks/Cole.
\end{References}
\begin{SeeAlso}\relax
\code{\LinkA{scan}{scan}}, \code{\LinkA{source}{source}}, \code{\LinkA{eval}{eval}},
\code{\LinkA{deparse}{deparse}}.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
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")
\end{ExampleCode}
\end{Examples}

