class Header

bartik.info.yml in drupal/core/themes/bartik/bartik.info.yml

drupal/core/themes/bartik/bartik.info.yml

block_test_theme.info.yml in drupal/core/modules/block/tests/themes/block_test_theme/block_test_theme.info.yml

drupal/core/modules/block/tests/themes/block_test_theme/block_test_theme.info.yml

template_preprocess_views_ui_view_preview_section in drupal/core/modules/views_ui/views_ui.theme.inc

Theme preprocess for theme_views_ui_view_preview_section().

ViewExecutable::viewsHandlerTypes in drupal/core/modules/views/lib/Drupal/views/ViewExecutable.php

Provide a list of views handler types used in a view, with some information about them.

_system_rebuild_theme_data in drupal/core/modules/system/system.module

Helper function to scan and collect theme .info.yml data and their engines.

class Header implements ToArrayInterface, \IteratorAggregate, \Countable {
  protected $values = array();
  protected $header;
  protected $glue;
  protected $stringCache;
  protected $arrayCache;

  /**
   * Construct a new header object
   *
   * @param string $header Name of the header
   * @param array  $values Values of the header
   * @param string $glue   Glue used to combine multiple values into a string
   */
  public function __construct($header, $values = array(), $glue = ', ') {
    $this->header = $header;
    $this->glue = $glue;
    if (null !== $values) {
      foreach ((array) $values as $key => $value) {
        if (is_numeric($key)) {
          $key = $header;
        }
        if ($value === null) {
          $this
            ->add($value, $key);
        }
        else {
          foreach ((array) $value as $v) {
            $this
              ->add($v, $key);
          }
        }
      }
    }
  }

  /**
   * Convert the header to a string
   *
   * @return string
   */
  public function __toString() {
    if (!$this->stringCache) {
      $this->stringCache = implode($this->glue, $this
        ->toArray());
    }
    return $this->stringCache;
  }

  /**
   * Add a value to the list of header values
   *
   * @param string $value  Value to add
   * @param string $header The exact header casing to add with. Defaults to the name of the header.
   *
   * @return Header
   */
  public function add($value, $header = null) {
    if (!$header) {
      $header = $this
        ->getName();
    }
    if (!array_key_exists($header, $this->values)) {
      $this->values[$header] = array(
        $value,
      );
    }
    else {
      $this->values[$header][] = $value;
    }
    $this
      ->clearCache();
    return $this;
  }

  /**
   * Get the name of the header
   *
   * @return string
   */
  public function getName() {
    return $this->header;
  }

  /**
   * Change the glue used to implode the values
   *
   * @param string $glue Glue used to implode multiple values
   *
   * @return Header
   */
  public function setGlue($glue) {
    $this->glue = $glue;
    $this->stringCache = null;
    return $this;
  }

  /**
   * Get the glue used to implode multiple values into a string
   *
   * @return string
   */
  public function getGlue() {
    return $this->glue;
  }

  /**
   * Normalize the header into a single standard header with an array of values
   *
   * @return Header
   */
  public function normalize() {
    $this
      ->clearCache();
    $this->values = array(
      $this
        ->getName() => $this
        ->toArray(),
    );
    return $this;
  }

  /**
   * Check if a particular case variation is present in the header
   * Example: A header exists on a message for 'Foo', and 'foo'. The Header object will contain all of the values of
   * 'Foo' and all of the values of 'foo'.  You can use this method to check to see if a header was set using
   * 'foo' (true), 'Foo' (true), 'FOO' (false), etc.
   *
   * @param string $header Exact header to check for
   *
   * @return bool
   */
  public function hasExactHeader($header) {
    return array_key_exists($header, $this->values);
  }

  /**
   * Check if the collection of headers has a particular value
   *
   * @param string $searchValue     Value to search for
   * @param bool   $caseInsensitive Set to TRUE to use a case insensitive search
   *
   * @return bool
   */
  public function hasValue($searchValue, $caseInsensitive = false) {
    foreach ($this
      ->toArray() as $value) {
      if ($value == $searchValue) {
        return true;
      }
      elseif ($caseInsensitive && !strcasecmp($value, $searchValue)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Remove a specific value from the header
   *
   * @param string $value Value to remove
   *
   * @return self
   */
  public function removeValue($searchValue) {
    foreach ($this->values as $key => $values) {
      foreach ($values as $index => $value) {
        if ($value == $searchValue) {
          unset($this->values[$key][$index]);
          $this
            ->clearCache();
          break 2;
        }
      }
    }
    return $this;
  }

  /**
   * Get all of the header values as a flat array
   * {@inheritdoc}
   */
  public function toArray() {
    if (!$this->arrayCache) {
      $this->arrayCache = array();
      foreach ($this->values as $values) {
        foreach ($values as $value) {
          $this->arrayCache[] = $value;
        }
      }
    }
    return $this->arrayCache;
  }

  /**
   * Get the raw data array of the headers. This array is represented as an associative array of the various cases
   * that might be stored in the header and an array of values associated with each case variation.
   *
   * @return array
   */
  public function raw() {
    return $this->values;
  }

  /**
   * Returns the total number of header values
   *
   * @return int
   */
  public function count() {
    return count($this
      ->toArray());
  }

  /**
   * Get an iterator that can be used to easily iterate over each header value
   *
   * @return \ArrayIterator
   */
  public function getIterator() {
    return new \ArrayIterator($this
      ->toArray());
  }

  /**
   * Clear the internal header cache
   */
  private function clearCache() {
    $this->arrayCache = null;
    $this->stringCache = null;
  }

}