Special characters in Rd example section will cause errors

Hi (Duncan?),

The other day I noticed some characters will cause errors in R CMD
CHECK because of parse_Rd(), and AFAIK, these chars include '%', '{'
and '}'. For example, note the comments in the example section:

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
\name{testfun}
\Rdversion{1.1}
\alias{testfun}
\title{
A Test
}
\description{
A test
}
\usage{
testfun()
}
\value{
NULL
}
\author{
Yihui Xie
}
\examples{
# special characters in comments
# what if a bracket '{' here?
}
\keyword{ misc }
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%

## error occurs

tools:::parse_Rd('testfun.Rd')

Error in tools:::parse_Rd("testfun.Rd") :
?testfun.Rd:23:1: unexpected section header
23: }
24: \keyword
? ?^

If I remove the '{', the Rd file can be parsed successfully. When you
put a code line with "%" in it, there will also be an error, e.g. you
put this in the example section

sprintf("%s", letters[1])

and you'll get

tools:::parse_Rd('testfun.Rd')

Error in tools:::parse_Rd("testfun.Rd") :
?Unexpected end of input (in " quoted string opened at testfun.Rd:23:10)
In addition: Warning message:
In tools:::parse_Rd("testfun.Rd") :
?newline within quoted string at testfun.Rd:24

Rd_parse() will parse the Rd file incorrectly either.

tools:::Rd_parse('testfun.Rd')

$meta
$meta$aliases
[1] "testfun"

$meta$concepts
character(0)

$meta$keywords
[1] "misc"

$meta$doc_type
character(0)

$meta$encoding
character(0)


$data
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? vals ? ? ? ?tags
1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? testfun ? ? ? ?name
2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1.1 ? Rdversion
3 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?\nA Test\n ? ? ? title
4 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?\nA test\n description
5 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? \ntestfun()\n ? ? ? usage
6 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?\nNULL\n ? ? ? value
7 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? \nYihui Xie\n ? ? ?author
8 \n# special characters in comments\n# what if ' ? ?examples

$rest
? ? ? ? examples
"'? or ''\n\n}\n"


Here is my session info:

sessionInfo()

R version 2.9.0 (2009-04-17)
i386-pc-mingw32

locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
States.1252;LC_MONETARY=English_United
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.
1252

attached base packages:
[1] stats ? ? graphics ?grDevices utils ? ? datasets ?methods ? base

R.version

? ? ? ? ? ? ? _
platform ? ? ? i386-pc-mingw32
arch ? ? ? ? ? i386
os ? ? ? ? ? ? mingw32
system ? ? ? ? i386, mingw32
status
major ? ? ? ? ?2
minor ? ? ? ? ?9.0
year ? ? ? ? ? 2009
month ? ? ? ? ?04
day ? ? ? ? ? ?17
svn rev ? ? ? ?48333
language ? ? ? R
version.string R version 2.9.0 (2009-04-17)


Regards,
Yihui
--
Yihui Xie <xieyihui at gmail.com>
Phone: +86-(0)10-82509086 Fax: +86-(0)10-82509086
Mobile: +86-15810805877
Homepage: http://www.yihui.name
School of Statistics, Room 1037, Mingde Main Building,
Renmin University of China, Beijing, 100872, China