Question

I have a string

"myhashkey?key1=val1&key2=val2&key3=val3&key4=val4"

that I want to explode into

myhashkey => {
   key1 => val1,
   key2 => val2,
   key3 => val3
}

I also want to collapse this back to the same string.

So far what I’ve come up with is pretty messy, using index and trying to build the values by hand

        $arg = $_[0];

#if arg has = it may be key=val string
        if(index($arg,'=') > -1 ){

#if arg has & character it might be key=val&key1=val

            if(index($arg,'&') > -1 ){

                #$arg =~ m/[=&\?]/
                @r = split(/[=&\?]/,$arg);
                my $hashkey = shift(@r)
                my %values = @r;
                return $class->$orig( key => $k, $value => \%values );
                ... 

            }else{
                @r = split('=',$arg);
                return ( key => $r[0], $value => $r[1] );
            }

        }

I don’t know how expensive the index(), split(), and join() functions are vs other methods of accomplishing this. I was thinking maybe I could use map + grep but I wasnt sure how to create the rergex for grep.

I also don’t want to reinvent the wheel so hopefully someone has a better idea of how to do this.

updated
BTW This is happening in the Moose BUILDARGS sub, so I don’t want to use a module like URI to parse the string everytime.

This is how I’m using the function in BUILDARGS

my $w = My::Param->new( 'hashkey?key1=val1&key2=val2&key3=val3');
my $x = My::Param->new( key => 'x', value => '7' );
my $y = My::Param->new( 'y=123' );

Produces this on print Dumper(*)

{ 'key1' => 'val1', 'key2' => 'val2', 'key3' => 'val3' }
bless( { 'key' => 'hashkey', 'meta_info' => [ #0 'hashkey?key1=val1&key2=val2&key3=val3' ], 'value' => { 'key1' => 'val1', 'key2' => 'val2', 'key3' => 'val3' } }, 'My::Param' )
bless( { 'key' => 'x', 'meta_info' => [ #0 'key', #1 'x', #2 'value', #3 '7' ], 'value' => '7' }, 'My::Param' )
bless( { 'key' => 'y', 'meta_info' => [ #0 'y=123' ], 'value' => '123' }, 'My:Param' )

Answer 1

In this case, the already invented wheel is named URI

$ perl -MData::Dumper -MURI -e'
    $uri = URI->new("myhashkey?key1=val1&key2=val2&key3=val3&key4=val4");
    $h{ $uri->path } = { $uri->query_form };
    print Dumper(\%h);
'