Source
File: wp-includes/kses.php
function wp_kses_attr( $element, $attr, $allowed_html, $allowed_protocols ) {
if ( ! is_array( $allowed_html ) ) {
$allowed_html = wp_kses_allowed_html( $allowed_html );
}
// Is there a closing XHTML slash at the end of the attributes?
$xhtml_slash = '';
if ( preg_match( '%\s*/\s*$%', $attr ) ) {
$xhtml_slash = ' /';
}
// Are any attributes allowed at all for this element?
$element_low = strtolower( $element );
if ( empty( $allowed_html[ $element_low ] ) || true === $allowed_html[ $element_low ] ) {
return "<$element$xhtml_slash>";
}
// Split it.
$attrarr = wp_kses_hair( $attr, $allowed_protocols );
// Go through $attrarr, and save the allowed attributes for this element
// in $attr2.
$attr2 = '';
foreach ( $attrarr as $arreach ) {
if ( wp_kses_attr_check( $arreach['name'], $arreach['value'], $arreach['whole'], $arreach['vless'], $element, $allowed_html ) ) {
$attr2 .= ' ' . $arreach['whole'];
}
}
// Remove any "<" or ">" characters.
$attr2 = preg_replace( '/[<>]/', '', $attr2 );
return "<$element$attr2$xhtml_slash>";
}