in reply to Finding the parent of a text in a file

You can transform the input lines into "full paths", i.e. include all the antecendents to each element. Then, you can just run standard diff (Algorithm::Diff) on the items: 
#!/usr/bin/perl
use warnings;
use strict;

use Algorithm::Diff qw{ diff };


open my $F1, '<', '1.in' or die $!;
my @lines1 = <$F1>;

open my $F2, '<', '2.in' or die $!;
my @lines2 = <$F2>;

chomp @lines1;
chomp @lines2;

# Transform the input lines.
my @path = q();
my @indent = q();
for my $line (@lines1, @lines2) {
    my ($this_indent, $key) = $line =~ /^( +)(.*)/;
    if ($this_indent eq $indent[-1]) {
        $path[-1] = $key

    } else {
        if ($this_indent le $indent[-1]) {
            pop @indent, pop @path while $indent[-1] ge $this_indent;
        }
        push @path, $key;
        push @indent, $this_indent;
    }
    $line = join '/', @path;
}

# Compare the lines.
my @diffs = diff(\@lines1, \@lines2);
for my $diff (@diffs) {
    for my $line (@$diff) {
        print "@$line\n";
    }
}

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Re^2: Finding the parent of a text in a file
by ExperimentsWithPerl (Acolyte) on Sep 04, 2015 at 22:48 UTC

    Thank you Choroba.This indeed looks useful.
    However this code is not able to proceed beyond
    $line = join '/', @path;
    (just before # Compare the lines)
    Its getting stuck there.

[reply]
      I ran it on the input you provided, I changed the 2nd file a bit more and got the following result: 
      - 5 /system/security/management-ip/protocol/shutdown
+ 5 /system/security/management-ip/protocol/reboot
- 7 /system/security/management-ip/protocol/entry 1
- 8 /system/security/management-ip/protocol/entry 1/snmp ok
+ 7 /system/security/management-ip/protocol/entry 2
+ 8 /system/security/management-ip/protocol/entry 2/snmp ok

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[reply]
[d/l]

        Thanks Choroba.
        Is it taking more time to complete.Because the code is showing no progress for few minutes.
        I tried to give some print statement just outside and inside the compare loop but nothing got printed.

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