function theme_rdf_metadata in Drupal 7

Returns HTML for a series of empty spans for exporting RDF metadata in RDFa.

Sometimes it is useful to export data which is not semantically present in the HTML output. For example, a hierarchy of comments is visible for a human but not for machines because this hiearchy is not present in the DOM tree. We can express it in RDFa via empty <span> tags. These aren't visible and give machines extra information about the content and its structure.

Parameters

$variables: An associative array containing:

• metadata: An array of attribute arrays. Each item in the array corresponds to its own set of attributes, and therefore, needs its own element.

See also

rdf_process()

Related topics

2 theme calls to theme_rdf_metadata()

rdf_preprocess_node in modules/rdf/rdf.module

Implements MODULE_preprocess_HOOK().

rdf_process in modules/rdf/rdf.module

Template process function for adding extra tags to hold RDFa attributes.

File

modules/rdf/rdf.module, line 858

Enables semantically enriched output for Drupal sites in the form of RDFa.

Code

function theme_rdf_metadata($variables) {
  $output = '';
  foreach ($variables['metadata'] as $attributes) {

    // Add a class so that developers viewing the HTML source can see why there
    // are empty <span> tags in the document.
    $attributes['class'][] = 'rdf-meta';
    $attributes['class'][] = 'element-hidden';

    // The XHTML+RDFa doctype allows either <span></span> or <span /> syntax to
    // be used, but for maximum browser compatibility, W3C recommends the
    // former when serving pages using the text/html media type, see
    // http://www.w3.org/TR/xhtml1/#C_3.
    $output .= '<span' . drupal_attributes($attributes) . '></span>';
  }
  return $output;
}