Truncate HTML String

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

I'm trying to extract the beginning of an HTML string, in a way that returns legal HTML, basically to generate a summary page of blog entries for the index. For an example entry

First a technological update - The code that drives this site is avail
+able for free on <a href="https://github.com/amacks/vatican_mss">GitH
+ub</a>.  I've just merged in a rather complex change to create proper
+ shelfmark sorting, fixing things like numbers-stored-as-strings and 
+handling roman numerals.  Two problems yet unfixed are Fonds <strong>
+P.I.O</strong>, with the middle "I" reading as a roman numeral, and <
+strong>Arch.Cap.S.Pietro</strong> where sub-set "I" is read as roman 
+1 and everything gets confused.</p>...
[download]

a naive perl substr($_,0,100), returns text ending "free on <a href="htt", which is bad

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Re: Truncate HTML String by Your Mother (Archbishop) on Dec 04, 2019 at 15:26 UTC
use strict; use warnings; use HTML::Truncate; my $snippet = <<""; First a technological update - The code that drives this site is avail +able for free on <a href="https://github.com/amacks/vatican_mss">GitH +ub</a>. I've just merged in a rather complex change to create proper + shelfmark sorting, fixing things like numbers-stored-as-strings and +handling roman numerals. Two problems yet unfixed are Fonds <strong> +P.I.O</strong>, with the middle "I" reading as a roman numeral, and < +strong>Arch.Cap.S.Pietro</strong> where sub-set "I" is read as roman +1 and everything gets confused.</p> my $ht = HTML::Truncate->new(); $ht->chars(100); print $ht->truncate($snippet), $/; __END__ First a technological update - The code that drives this site is avail +able for free on <a href="https://github.com/amacks/vatican_mss">GitH +ub</a>. I've… [download] HTML::Truncate. Long time since I used this for anything but it helped me out with similar needs a long time ago. There are lots of low level tools to do this kind of thing but you end up having to do a lot of #text character counting and such. And that’s why this one breaks much later than your raw `substr`; it’s only counting displayed characters, not HTML content. Update: if we correct your omission of the opening paragraph tag in the input, this is the output– `<p>First a technological update - The code that drives this site is av +ailable for free on <a href="https://github.com/amacks/vatican_mss">G +itHub</a>. I've…</p>` [download]	[reply] [d/l] [select]

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Re: Truncate HTML String
by Your Mother (Archbishop) on Dec 04, 2019 at 15:26 UTC

use strict;
use warnings;
use HTML::Truncate;

my $snippet = <<"";
First a technological update - The code that drives this site is avail
+able for free on <a href="https://github.com/amacks/vatican_mss">GitH
+ub</a>.  I've just merged in a rather complex change to create proper
+ shelfmark sorting, fixing things like numbers-stored-as-strings and 
+handling roman numerals.  Two problems yet unfixed are Fonds <strong>
+P.I.O</strong>, with the middle "I" reading as a roman numeral, and <
+strong>Arch.Cap.S.Pietro</strong> where sub-set "I" is read as roman 
+1 and everything gets confused.</p>

my $ht = HTML::Truncate->new();
$ht->chars(100);
print $ht->truncate($snippet), $/; 

__END__
First a technological update - The code that drives this site is avail
+able for free on <a href="https://github.com/amacks/vatican_mss">GitH
+ub</a>. I've&#8230;
[download]

HTML::Truncate. Long time since I used this for anything but it helped me out with similar needs a long time ago. There are lots of low level tools to do this kind of thing but you end up having to do a lot of #text character counting and such.

And that’s why this one breaks much later than your raw substr; it’s only counting displayed characters, not HTML content.

Update: if we correct your omission of the opening paragraph tag in the input, this is the output–

<p>First a technological update - The code that drives this site is av
+ailable for free on <a href="https://github.com/amacks/vatican_mss">G
+itHub</a>. I've&#8230;</p>
[download]

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