From m_olshansky at yahoo.com  Thu Aug 17 09:45:02 2017
From: m_olshansky at yahoo.com (Moshe Olshansky)
Date: Thu, 17 Aug 2017 07:45:02 +0000 (UTC)
Subject: [Rd] Problem with a regular expression.
In-Reply-To: <5995451B.5040708@sapo.pt>
References: <65e225958ba74a7dbcf0bc4688387e9d@uxcn13-ogg-c.UoA.auckland.ac.nz>
 <5995451B.5040708@sapo.pt>
Message-ID: <1783369282.3222160.1502955902026@mail.yahoo.com>

I tried this on a Linux (Ubuntu) server invoking R from the command line and the result was the same, except that I could kill the R session from another terminal window.


      From: Rui Barradas <ruipbarradas at sapo.pt>
 To: Chris Triggs <cm.triggs at auckland.ac.nz>; "r-devel at r-project.org" <r-devel at r-project.org> 
Cc: Thomas Lumley <t.lumley at auckland.ac.nz>
 Sent: Thursday, 17 August 2017, 17:26
 Subject: Re: [Rd] Problem with a regular expression.
   
Hello,

This seems to be serious.
RGui.exe, fresh session. I've clicked File > New Script and wrote

Oldterm <- c("A", "B", "A", "*", "B")
strsplit(Oldterm, "\\\\)" )

Ran each instruction at a time with Ctrl+r and with the strsplit call 
the system froze.

Ctrl+Alt+Del didn't work, I had to go for the power switch button.

sessionInfo()
R version 3.4.1 (2017-06-30)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

Matrix products: default

locale:
[1] LC_COLLATE=Portuguese_Portugal.1252 
LC_CTYPE=Portuguese_Portugal.1252
[3] LC_MONETARY=Portuguese_Portugal.1252 LC_NUMERIC=C 

[5] LC_TIME=Portuguese_Portugal.1252

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

loaded via a namespace (and not attached):
[1] compiler_3.4.1


Rui Barradas

Em 16-08-2017 23:31, Chris Triggs escreveu:
> Hi...
>
> I have come upon a problem with a regular expression which causes base-R to freeze.? I have reproduced the phenomenon on several machines running R under Windows 10, and also under OSX? on different Apple MACs.
>
> The minimal example is:-
> Oldterm is a vector of characters, e.g. "A", "B", "A", "*", "B"
> The regular expression is "\\\\)"
>
> The call which freezes R is
> strsplit(Oldterm, "\\\\)" )
>
> Thomas - after he had reproduced the problem - suggested that I submit it to r-devel.
>
> Best wishes....
>? ? ? ? ? ? Chris Triggs
>
>
> ??? [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

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[Rd] Problem with a regular expression.
Moshe Olshansky