Section Handling

veera has asked for the wisdom of the Perl Monks concerning the following question:

I have some data in file as

<1>one</1>
data data data data
<2>two</2>
data data data data
<3>three</3>
data data data data
<3>blah</3>
data data data data
<2>blah</2>
data data data data
<4>zoom</4>
data data data data
<4>zoom</4>
data data data data
<1>data</1>
[download]

i need the output as

<1>one
data data data data
<2>two
data data data data
<3>three
data data data data
</3>
<3>blah
data data data data
</3>
</2>
<2>blah
data data data data
<4>zoom
data data data data
</4>
<4>zoom
data data data data
</4>
</2>
</1>
<1>data
data data data data
</1>
[download]

The closing should be as the in nested order.

Comment on Section Handling - Nested Select or Download Code

Replies are listed 'Best First'.
Re: Section Handling - Nested by tobyink (Canon) on Jun 20, 2013 at 22:20 UTC
What have you tried so far? What problems have you encountered? `package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name`	[reply]
Re: Section Handling - Nested by kcott (Archbishop) on Jun 20, 2013 at 22:38 UTC
G'day veera, Please read: "Do Your Own Work" in How (Not) To Ask A Question. Then read: How do I post a question effectively?. Thankyou. -- Ken	[reply]
Re: Section Handling - Nested by hdb (Monsignor) on Jun 21, 2013 at 05:44 UTC
In your output, where is the last "data data data data" line coming from? In the input there are 7 such lines, in the output, there are 8! This is a really nice question and can be very elegantly solved using an array as a stack.	[reply]
Re^2: Section Handling - Nested by hdb (Monsignor) on Jun 21, 2013 at 13:02 UTC
After I claimed earlier today, that the problem has an elegant solution based on a stack, I have to publish my proposal here, despite the fact that there is no sign that veera has spend any effort on solving this. `use strict; use warnings; my @stack; while(<DATA>) { if( s\|^(<(\d+)>.*)(</\2>\n)\|$1\n\| ) { print pop @stack while @stack and substr( $stack[-1], 2, -2 ) >= $ +2; push @stack, $3; } print; } print reverse @stack; __DATA__ <1>one</1> data data data data <2>two</2> data data data data <3>three</3> data data data data <3>blah</3> data data data data <2>blah</2> data data data data <4>zoom</4> data data data data <4>zoom</4> data data data data <1>data</1> data data data data` [download]	[reply] [d/l]