Restriction digest of a circular plasmid

public function restrictionDigest(
    GenbankPlasmidMapperInterface $genbankPlasmidMapper,
    RestrictionEnzymeCatalogInterface $enzymeCatalog,
    RestrictionDigestInterface $restrictionDigest,
    RestrictionEndCompatibilityInterface $endCompatibility
) {
    $oPlasmid = $this->loadPuc19($genbankPlasmidMapper); // see "Plasmid from GenBank"
 
    // Opening the polylinker with two enzymes leaves two fragments with different sticky ends
    $oDouble = $restrictionDigest->digest($oPlasmid, [
        $enzymeCatalog->getByName("EcoRI"),
        $enzymeCatalog->getByName("HindIII"),
    ]);
 
    // PvuII cuts twice, on both sides of the polylinker, and leaves blunt ends
    $oPvuII = $restrictionDigest->digest($oPlasmid, [$enzymeCatalog->getByName("PvuII")]);
 
    // Can these ends be ligated together?
    $oEcoRIEnd = $oDouble->getCuts()[0]->getEnd();
    $oHindIIIEnd = $oDouble->getCuts()[1]->getEnd();
    $aCompatibility = [
        "EcoRI / HindIII" => $endCompatibility->checkCompatibility($oEcoRIEnd, $oHindIIIEnd),
        "EcoRI / MfeI"    => $endCompatibility->checkCompatibility($oEcoRIEnd, new RestrictionEnd(RestrictionEnd::FIVE_PRIME, "AATT")),
        "BamHI / BglII"   => $endCompatibility->checkCompatibility(
            new RestrictionEnd(RestrictionEnd::FIVE_PRIME, "GATC"),
            new RestrictionEnd(RestrictionEnd::FIVE_PRIME, "GATC")
        ),
        "PvuII / EcoRV"   => $endCompatibility->checkCompatibility(
            $oPvuII->getCuts()[0]->getEnd(),
            new RestrictionEnd(RestrictionEnd::BLUNT)
        ),
    ];
 
    return $this->render('default/cloningRestrictionDigest.html.twig', [
        'digests'       => ["EcoRI + HindIII" => $oDouble, "PvuII" => $oPvuII],
        'compatibility' => $aCompatibility,
    ]);
}