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parser does not catch strings without closing quote

4 messages · William Dunlap, Duncan Murdoch

Original
William Dunlap
# 
Shouldn't the parser complain about unfinished strings in files?
It doesn't and will tack on a newline if there isn't one there. 

  > withOption <- function(optionList, expr) {
  +     oldOption <- options(optionList)
  +     on.exit(options(oldOption))
  +     expr
  + }

  > cat(file=tf<-tempfile(), "\"string without closing quote\n")
  > p <- withOption(list(keep.source=FALSE), parse(tf))
  > p
  expression("string without closing quote\n")

  > cat(file=tf<-tempfile(), "\"string with no closing quote nor newline")
  > p <- withOption(list(keep.source=FALSE), parse(tf))
  > p
  expression("string with no closing quote nor newline\n")

It does complain when parsing a character string with the same problem.
  > p <- withOption(list(keep.source=FALSE), parse(text="\"unfinished string"))
  Error in parse(text = "\"unfinished string") :
    2:0: unexpected end of input
  1: "unfinished string
    ^

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
Duncan Murdoch
#
On 11-09-01 6:24 PM, William Dunlap wrote:
I assume this is a bug, but the way the parser handles input is quite a 
mess, so I'm not sure where to fix this.  The obvious place (within the 
parser where it is getting tokens) does not work:  the higher level code 
breaks up input into small pieces, and the parser frequently hits the 
end of a piece (at a newline or semicolon, for example), and signals an 
incomplete parse, which is restarted.

(For others than Bill:  this is necessary because the S language doesn't 
have a clear end of statement marker.  If the parser sees "x + ", it 
tries to get more input to finish the statement.  It's only an error if 
nothing more is there.)

A possibility would be to add a new token "incomplete string", which 
will eventually trigger an error if the restart doesn't complete it.

I'll think about it...

Duncan Murdoch
William Dunlap
# 
By the way, I noticed the problem in R because S+ could not
parse a file in the CRAN package SAPP because it ended with
a garbage line with a quote in it:

  % tail -3 SAPP/data/res2003JUL26.R
  res2003JUL26 <- data.frame(res2003JUL26)
  names(res2003JUL26) <- c("no.", "longitude", "latitude", "magnitude", "time", "depth", "trans.time")
  ")

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
Duncan Murdoch
#
On 02/09/2011 11:28 AM, William Dunlap wrote:
Thanks.  I tried adding the new token type, and it seems to work, and to 
give reasonably intelligible error messages.  So I'll probably commit 
that, as well as the octal upper limit change.

Duncan