Thanks for all the reply. and this problem has been solved.
but sorry for my poor understanding on regex, and having to trouble
you again,
here I have another little problem:
if the content ends with a real single backslash, I need read in the
next line.
How to use regex to do this?
for example:
line ends with match
\ yes
\\ no
\\\ yes
\\\\ no
Thanks for any help again.
I assume this pertains to the rules set out on the properties
in the original problem statement.
Tad's solution to check then end for 'odd' number of '\' works best
for a line continuation.
Be very cautious!! If you are trying to find a way to fix random
line splits when this file was generated, there is absolutely
NO solution available to you at all !!!
The reason is you already have escaping rules in place
The line split must be intelligently constucted in that only
an odd number of '\' at the end will determine line continuation.
And at the same time be used in the general escaping rules after
it is joined.
You can't just add a '\' where you would like to split the line then
remove it later without counting the existing escapes at the end.
Either way it takes intelligence to construct the file given the
existing escaping rules you laid out for yourself.
Notice the places where the split occurs in DATA below..
Even if you had an intelligent generator that splits the
line on a '\', it could still split on an even boundry.
Or say it adds a complement to make the split odd, still,
even then, the original can not be guaranteed to reassemble
because this conflicts with the original escape logic..
There is no solution then!
sln
use strict;
use warnings;
# ** Original
# expression means: key value
# a=b=c a b=c
# a\=b=c a=b c
# a\\=b=c a\ b=c
# a\\\=b=c a\=b c
# ** Output
# a=b=c a b=c
# a\=b=c a=b c
# a\\=b=c a\ b=c
# a\\\=b=c a\=b c
# a\\\\=b=c a\\ b=c
# a\\\=b\\=c a\=b\ c
# a\\=b\\=c a\ b\=c
# a=b=c a b=c
# a\=b=c a=b c
# a\\=b=c a\ b=c
# a\\\=b=c a\=b c
# a\\\\=b=c a\\ b=c
# a\\\=b\\=c a\=b\ c
# a\\=b\\=c a\ b\=c
my $buf = '';
print "\nexpression means:\tkey\tvalue\n";
foreach ( <DATA> ) {
chomp;
$_ = $buf . $_;
if ( /(\\+)$/ and length($1) % 2 ) {
# wouldn't want to do this -> s/\\$//;
$buf .= $_; # cat this line to buffer
next; # read next line
}
if (/^((?
?:\\.)*?|.*?)+)=(.*)$/) {
# unescape built in sequences
my ($key, $val) = ($1,$2);
$key =~ s/\\(.)/$1/g;
$val =~ s/\\(.)/$1/g;
printf "%-20s\t%s\t%s\n", $_, $key, $val;
}
$buf = '';
}
__DATA__
# no line splits
a=b=c
a\=b=c
a\\=b=c
a\\\=b=c
a\\\\=b=c
a\\\=b\\=c
a\\=b\\=c
# ok line splits
a=b=c
a\
=b=c
a\
\=b=c
a\\\
=b=c
a\\\
\=b=c
a\\\=b\
\=c
a\\=b\
\=c
#some good/bad line splits
a=b=c
a\
=b=c
a\\
=b=c
a\\\
=b=c
a\\\\
=b=c
a\\\
=b\\=c
a\\=b\\
=c
