Answer to
this node.
Merges multiple hashes recursively.
Usage: $href = mergehashes(\%h1,%h2,%h3);
Keys' values are turned into an array ref.
Any key that has a single non-ref value will be converted back to a scalar.
Dies on circular references. (This is a feature)
#!/usr/bin/perl -w
use warnings;
use strict;
BEGIN {
my %SeenMerged = ();
sub mergehashes{ # Dies on circular references
my @hashrefs = @_;
die "Passed a non hashref" if grep { ref $_ ne 'HASH' } @h
+ashrefs;
my %merged = ();
my @seen = grep { ref $_ eq 'HASH' } @SeenMerged{@hashref
+s}; # Break circular links..
if (@seen){
die "contains a circular reference! bailing...";
}
@SeenMerged{@hashrefs} = @hashrefs;
foreach my $h (@hashrefs){
while (my ($k,$v) = each %$h ){
push @{$merged{$k}}, $v;
}
}
while (my ($k,$v) = each %merged){
my @hashes = grep { ref $_ eq 'HASH' } @$v;
$merged{$k} = $v->[0] if (@$v == 1 && !ref $v->[0]);
+
$merged{$k} = mergehashes(@hashes) if @hashes;
}
delete @SeenMerged{@hashrefs};
return \%merged;
}
}
# EXAMPLE
use Data::Dumper;
my (%hash1,%hash2);
%hash1 = (
red => 1,
brown => {
green => 1,
blue => {
yellow => 1,
},
black => 1,
},
gray => 1,
);
%hash2 = (
white => 1,
brown => {
purple => 1,
},
);
my $merged = mergehashes(\%hash1, \%hash2 );
print Dumper($merged);
__END__
outputs
$VAR1 = {
'gray' => 1,
'white' => 1,
'brown' => {
'blue' => {
'yellow' => 1
},
'purple' => 1,
'green' => 1,
'black' => 1
},
'red' => 1
};
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.