I think that for many HTML tasks HTML::TokeParser is a good module, it is a slightly simpler interface to HTML::Parser. When you parse with HTML::Parser you have to have all of your handlers and logic set up before you can call parse(). But HTML::TokeParser will turn the entire HTML document into a stack of tokens that you can shift and unshift as needed. The tokens correspond to each element of your HTML page.

Because your program's logic is based on just a few criteria happening in an order, this is the perfect time for that. Here is some pseudocode that would use HTML::TokeParser:

#Get HTML Document
#HTML::TokeParser->new( HTML )
#get first Token
#until ( TokenTag eq 'h3' and TokenText eq 'foo')
#    get next Token
#if EndOfHTML then exit
#until ( TokenTag eq 'em' )
#    get next Token
#declare EM container
#until ( get TokenTag eq 'hr' )
#    add TokenText to EM container
#    get next Token
#use EM container
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As you can see, this logic is a lot simpler than trying to set up handlers for each of the tags you care about, then trying to manage states-- which is about what you have to do with HTML::Parser.

#!/usr/local/bin/perl -w

###########################################################
# includes ################################################
###########################################################
use strict;
use HTML::TokeParser;

#################
### Variables ###
#################
my $file_in = 'test.html';

##################
### Parse HTML ###
##################
my $p = HTML::TokeParser->new($file_in) || die "Can't open: $!";
##
while (my $token = $p->get_token) {
    my $token_type = @$token[0];
    start(@$token[1], @$token[4]) if ($token_type =~ /S/i); # Start Ta
+g
    end(@$token[1], @$token[2]) if ($token_type =~ /E/i); # End Tag
    text(@$token[1]) if ($token_type =~ /T/i); # Text
    comment(@$token[1]) if($token_type =~ /C/i); # Comment
    declaration(@$token[1]) if ($token_type =~ /D/i); # Declaration
}

###########################################################
# SUB's ###################################################
###########################################################

#############
### DTD's ###
#############
sub declaration {
    my ($declaration) = @_;
    print "DEC: $declaration\n";
}

################
### Comments ###
################
sub comment {
    my ($comment) = @_;
    print "CMT: $comment\n";
}

#####################
### Text Entities ###
#####################
sub text {
    my ($text) = @_;
    return if ($text =~ /^(\s+)$/); #skip blank lines
    $text =~ s/\s+/ /g; #kill off big chunks of whitespace
    $text =~ s/\n//g; #keep text split across lines together
    print "TEXT: $text\n";
}

##################
### Start Tags ###
##################
sub start {
    my ($tag, $origtext) = @_;
    chomp $origtext;
    print "ST: $tag = $origtext\n";
}

################
### End Tags ###
################
sub end {
    my ($tag, $origtext) = @_;
    chomp $origtext;
    print "ET: $tag = $origtext\n";
}
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