"Dharshana Eswaran" schreef:
You really shouldn't quote text that is no longer relevant, such as
signatures and mailing list tails.
> Ruud:
>> Dharshana Eswaran:
>>> i am trying to grep for a string in the file and once i get the
>>> string, I need to read few lines which occurs before the string.
>>
>> The classic (state machine) approach is to start storing strings from
>> the start marker, so "typedef union" here, and discard the stored
>> lines when the search string doesn't pop-up.
>
> Can you please help me with a small piece of code for the same logic
> which you mentioned?
#!/usr/bin/perl
use strict;
use warnings;
my $phase = 0;
my $s;
while (<>) {
if (0 == $phase) {
/^\s*typedef union\s*(?:\{\s*)?$/
and ++$phase and $s = $_;
}
elsif (1 == $phase) {
$s .= $_;
if (/^\s*}\s*(\w+)\s*;\s*$/) {
'CHANNEL_INFO_T' eq $1
and ++$phase and last;
$s = '';
$phase--;
}
}
else { die "ugly phase($phase)"}
}
$phase == 2 and print $s;
__END__
(untested)
But a real parser would also catch variants such as
typedef union {
TYPE_T type;
MODE_T mode;
}
CHANNEL_INFO_T;
See also:
http://search.cpan.org/search?query=balanced&mode=module
--
Affijn, Ruud
"Gewoon is een tijger."
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