parse_Rd: Parse an Rd File

Description

This function reads an R documentation (Rd) file and parses it, for processing by other functions.

Usage

parse_Rd(file, srcfile = NULL, encoding = "unknown",
         verbose = FALSE, fragment = FALSE, warningCalls = TRUE,
	 macros = file.path(R.home("share"), "Rd", "macros", "system.Rd"),
         permissive = FALSE)
# S3 method for Rd
print(x, deparse = FALSE, …)
# S3 method for Rd
as.character(x, deparse = FALSE, …)

Arguments

file

A filename or text-mode connection. At present filenames work best.

srcfile

NULL, or a "srcfile" object. See the ‘Details’ section.

encoding

Encoding to be assumed for input strings.

verbose

Logical indicating whether detailed parsing information should be printed.

fragment

Logical indicating whether file represents a complete Rd file, or a fragment.

warningCalls

Logical: should parser warnings include the call?

macros

Filename or environment from which to load additional macros, or a logical value. See the Details below.

permissive

Logical indicating that unrecognized macros should be treated as text with no warning.

An object of class Rd.

deparse

If TRUE, attempt to reinstate the escape characters so that the resulting characters will parse to the same object.

…

Further arguments to be passed to or from other methods.

Value

parse_Rd returns an object of class "Rd". The internal format of this object is subject to change. The as.character() and print() methods defined for the class return character vectors and print them, respectively.

Unless macros = FALSE, the object will have an attribute named "macros", which is an environment containing the macros defined in file, in a format that can be used for further parse_Rd calls in the same session. It is not guaranteed to work if saved to a file and reloaded in a different session.

Details

This function parses Rd files according to the specification given in https://developer.r-project.org/parseRd.pdf.

It generates a warning for each parse error and attempts to continue parsing. In order to continue, it is generally necessary to drop some parts of the file, so such warnings should not be ignored.

Files without a marked encoding are by default assumed to be in the native encoding. An alternate default can be set using the encoding argument. All text in files is translated to the UTF-8 encoding in the parsed object.

As from R version 3.2.0, User-defined macros may be given in a separate file using \newcommand or \renewcommand. An environment may also be given: it would be produced by loadRdMacros, loadPkgRdMacros, or by a previous call to parse_Rd. If a logical value is given, only the default built-in macros will be used; FALSE indicates that no "macros" attribute will be returned with the result.

The permissive argument allows text to be parsed that is not completely in Rd format. Typically it would be LaTeX code, used in an Rd fragment, e.g.in a bibentry. With permissive = TRUE, this will be passed through as plain text. Since parse_Rd doesn't know how many arguments belong in LaTeX macros, it will guess based on the presence of braces after the macro; this is not infallible.

References

https://developer.r-project.org/parseRd.pdf