use blib;
use Hash::Bidirectional;
use Benchmark qw(cmpthese);
use Devel::Size qw(total_size);

use strict;
use warnings;

my $hn = {};
my $hb = bless {}, 'Hash::Bidirectional';

my $i = 0;
for ( 'aaaaz' .. 'zzzzz') {
    $i++;
    $hn->{$_} = $i;   # - normal hash
    $hn->{$i} = $_;   # /
    $hb->pair($_,$i); # - bidirectional hash
}
print "size normal hash: ", total_size($hn),"\n";
print "size bi_dir hash: ", total_size($hb),"\n";

cmpthese( 10000000, {
    normal => sub { $hn->{$hn->{shmem}} },
    bi_dir => sub { $hb->get($hb->get('shmem')) },
});
__END__
size normal hash: 3025679168
size bi_dir hash: 2360323536
            Rate bi_dir normal
bi_dir 2801120/s     --   -62%
normal 7407407/s   164%     --

##</code><code>##

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "perlapi.h"
#include "ppport.h"

HE * get_entry(HE * he, U32 hash) {
    HE *entry = he;
    for(; entry; entry = HeNEXT(entry)) {
        if (HeHASH(entry) != hash){
            continue;
        }
    }
    if (!entry) entry = he;
    return entry;
}

MODULE = Hash::Bidirectional            PACKAGE = Hash::Bidirectional

char * pair(HV *hv, char *key, SV *value)
CODE:
    SV **key_ptr;
    SV **value_ptr;
    char *v = SvPVbyte_nolen(value);
    U32 hash = 0;
    HE *ventry;
    HE *kentry;
    SV *ksv;
    SV *vsv;
    
    /* store key as key */
    PERL_HASH(hash, key, strlen(key));
    ksv = newSViv((IV) &key);
    key_ptr = hv_store(hv, key, strlen(key), ksv, hash);
    kentry = get_entry((HvARRAY(hv))[hash & (I32) HvMAX(hv)],hash);

    /* store value as key */
    hash = 0;
    PERL_HASH(hash, v, strlen(v));
    vsv = newSViv((IV) &v);
    value_ptr = hv_store(hv, v, strlen(v), vsv, hash);
    ventry = get_entry((HvARRAY(hv))[hash & (I32) HvMAX(hv)],hash);

    /* set pointers of each */
    sv_setiv(ksv,(IV)HeKEY(ventry));
    sv_setiv(vsv,(IV)HeKEY(kentry));
    RETVAL = v;
OUTPUT:
    RETVAL

char * get(HV *hv, char *key)
CODE:
    HE *entry;
    U32 hash;

    PERL_HASH(hash, key, strlen(key));
    entry = get_entry((HvARRAY(hv))[hash & (I32) HvMAX(hv)],hash);
    RETVAL= (char*) SvIVX(HeVAL(entry));
OUTPUT:
    RETVAL