function isbn($isbn)
{
if (preg_match("/[^0-9 IXSBN-]/", $isbn)) {
return false;
}
$isbn = strtoupper($isbn);
$isbn = str_replace(array('ISBN', '-', ' ', "\t", "\n"), '', $isbn);
if (strlen($isbn) == 13) {
return Validate_ISPN::isbn13($isbn);
} elseif (strlen($isbn) == 10) {
return Validate_ISPN::isbn10($isbn);
}
return false;
}
/**
* Looks at 020$a and reports errors if the check digit is wrong.
* Looks at 020$z and validates number if hyphens are present.
*
* @param File_MARC_Field $field Field to check
*
* @return void
*/
protected function check020($field)
{
foreach ($field->getSubfields() as $current) {
$data = $current->getData();
// remove any hyphens
$isbn = str_replace('-', '', $data);
// remove nondigits
$isbn = preg_replace('/^\\D*(\\d{9,12}[X\\d])\\b.*$/', '$1', $isbn);
if ($current->getCode() == 'a') {
if (substr($data, 0, strlen($isbn)) != $isbn) {
$this->warn("020: Subfield a may have invalid characters.");
}
// report error if no space precedes a qualifier in subfield a
if (preg_match('/\\(/', $data) && !preg_match('/[X0-9] \\(/', $data)) {
$this->warn("020: Subfield a qualifier must be preceded by space, {$data}.");
}
// report error if unable to find 10-13 digit string of digits in
// subfield 'a'
if (!preg_match('/(?:^\\d{10}$)|(?:^\\d{13}$)|(?:^\\d{9}X$)/', $isbn)) {
$this->warn("020: Subfield a has the wrong number of digits, {$data}.");
} else {
if (strlen($isbn) == 10) {
if (!Validate_ISPN::isbn10($isbn)) {
$this->warn("020: Subfield a has bad checksum, {$data}.");
}
} else {
if (strlen($isbn) == 13) {
if (!Validate_ISPN::isbn13($isbn)) {
$this->warn("020: Subfield a has bad checksum (13 digit), {$data}.");
}
}
}
}
} else {
if ($current->getCode() == 'z') {
// look for valid isbn in 020$z
if (preg_match('/^ISBN/', $data) || preg_match('/^\\d*\\-\\d+/', $data)) {
// ##################################################
// ## Turned on for now--Comment to unimplement ####
// ##################################################
if (strlen($isbn) == 10 && Validate_ISPN::isbn10($isbn) == 1) {
$this->warn("020: Subfield z is numerically valid.");
}
}
}
}
}
}
