[bug-gawk] regexp RS mangling input

[Jay Michael]

     I'm using a regular expression as RS to soak up everything I don't 
want to see while parsing my input.  I want the record terminator to 
include possibly multi-line expanses enclosed in braces.

     The first problem I had, gawk seemed to be returning the same 
string for several consecutive internal records.  When I tried to track 
down what I was doing wrong, my reduced test case caused gawk to include 
what should have been the first record in the first record's terminator, 
while ending the terminator before the end of the second "comment". 
Then, gawk acted like each character was a record terminator.

     I'm running GNU Awk 3.1.3 under Windows XP.  I don't know who 
built it, I don't remember where I got it.  I tried on a UNIX/Linux 
shell to which I have access.  It was running 3.1.1 (or so), it behaved 
the same way as the version on my PC.

     I have attached my program (d.awk) and input (d.i).  d.log is not 
really a log file -- I pasted pieces and then appended the output of
"gawk -f d.awk d.i".

function make_printable( s,   p )
{
  p = s ;
  gsub( /\n/, "\\n", p ) ;
  gsub( /\r/, "\\r", p ) ;
  gsub( /\t/, "\\t", p ) ;
  return p ;
} # make_printable

BEGIN {
  re_bcom = "\\{[^{}]*\\}" ;
    RS = "([ \\n]|(" re_bcom "))*" ;
    print "RS = " make_printable( RS ) ;
}

{
  print "RS = " make_printable(RS) \
        " $0 = " make_printable($0) " RT = " make_printable( RT ) ;
}

first
  {1st comment}

  {2nd comment}
last

GNU Awk 3.1.3


d.awk:
function make_printable( s,   p )
{
  p = s ;
  gsub( /\n/, "\\n", p ) ;
  gsub( /\r/, "\\r", p ) ;
  gsub( /\t/, "\\t", p ) ;
  return p ;
} # make_printable

BEGIN {
  re_bcom = "\\{[^{}]*\\}" ;
    RS = "([ \\n]|(" re_bcom "))*" ;
    print "RS = " make_printable( RS ) ;
}

{
  print "RS = " make_printable(RS) \
        " $0 = " make_printable($0) " RT = " make_printable( RT ) ;
}


d.i:
first
  {1st comment}

  {2nd comment}
last


gawk -f d.awk d.i
RS = ([ \n]|(\{[^{}]*\}))*
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = first\n  {1st comment}\n\n  {2nd comm
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = e
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = n
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = t
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = }
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = \n
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = l
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = a
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = s
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = t
RS = ([ \n]|(\{[^{}]*\}))* $0 =  RT = \n