The regular expressions in compareVersion()

On Thu, Apr 24, 2014 at 1:42 PM, Duncan Murdoch
On 24/04/2014, 1:11 PM, Yihui Xie wrote:
Hi,

I guess the backslash should not be used as the separator for
strsplit() in compareVersion(), because the period in [.] is no longer
a metacharacter (no need to "escape" it using a backslash):

https://github.com/wch/r-source/blob/trunk/src/library/utils/R/packages.R#L866-L867

compareVersion
function (a, b)
{
....
     a <- as.integer(strsplit(a, "[\\.-]")[[1L]])
     b <- as.integer(strsplit(b, "[\\.-]")[[1L]])
....
<environment: namespace:utils>

Could you post an example where this causes trouble, or are you just
suggesting this as a way to make the source a little cleaner?
Maybe it's already clear, but [\\.] is the set for the two symbols '\'
and '.', not '.' alone.  For example, I would expect an error below:
compareVersion("3.14-59.26", "3.14-59\\26")
[1] 0

/Henrik

A similar regular expression problem also exists in the Sweave syntax
(for \Sexpr{}), and I have reported it once. It was fixed but the fix
was immediately reverted for some reason:

https://github.com/wch/r-source/commit/52b0a46e15136a7f9e4777e9960fdda6d84880c0

A link to your report would be more useful, if it included an example where
the bad regexp causes trouble.

Duncan Murdoch

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The regular expressions in compareVersion()

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