Apply filters over the iterable values of a DatePeriod object.

DatePeriod_Filter.php

<?php
/**
 * Apply filters over the iterable values of a DatePeriod object
 * 
 * @method self monday    Include Mondays    while iterating the DatePeriod
 * @method self tuesday   Include Tuesdays   while iterating the DatePeriod
 * @method self wednesday Include Wednesdays while iterating the DatePeriod
 * @method self thursday  Include Thursdays  while iterating the DatePeriod
 * @method self friday    Include Fridays    while iterating the DatePeriod
 * @method self saturday  Include Saturdays  while iterating the DatePeriod
 * @method self sunday    Include Sundays    while iterating the DatePeriod
 * 
 * @method self weekdays Include weekdays while iterating the DatePeriod
 * @method self weekends Include weekends while iterating the DatePeriod
 * 
 * @method self am Include AM DateTimes while iterating the DatePeriod 
 * @method self pm Include PM DateTimes while iterating the DatePeriod
 * 
 * @method self january   Include days in January   while iterating the DatePeriod
 * @method self february  Include days in February  while iterating the DatePeriod
 * @method self march     Include days in March     while iterating the DatePeriod
 * @method self april     Include days in April     while iterating the DatePeriod
 * @method self may       Include days in May       while iterating the DatePeriod
 * @method self june      Include days in June      while iterating the DatePeriod
 * @method self july      Include days in July      while iterating the DatePeriod
 * @method self august    Include days in August    while iterating the DatePeriod
 * @method self september Include days in September while iterating the DatePeriod
 * @method self october   Include days in October   while iterating the DatePeriod
 * @method self november  Include days in November  while iterating the DatePeriod
 * @method self december  Include days in December  while iterating the DatePeriod
 */

class DatePeriod_Filter extends FilterIterator
{

	/**
	 * Array of days to filter
	 * 
	 * @var array
	 * <ul>
	 * 	<li>@key string day => @type boolean true
	 * 	...
	 * </ul>
	 */
	private $_dayFilter = [];

	/**
	 * Array of ante/post meridiems to filter
	 * 
	 * @var array
	 * <ul>
	 * 	<li>@key string 'am' => @type boolean true
	 * 	<li>@key string 'pm' => @type boolean true
	 * </ul>
	 */
	private $_meridiemFilter = [];

	/**
	 * Array of months to filter
	 * 
	 * @var array
	 * <ul>
	 * 	<li>@key string month => @type boolean true
	 * 	...
	 * </ul>
	 */
	private $_monthFilter = [];

	/**
	 * Array of user filters
	 * 
	 * @var array
	 * <ul>
	 * 	<li>@type callable Invoked with the current DateTime object and is expected to return a boolean
	 * 	...
	 * </ul>
	 */
	private $_userFilter = [];

	/**
	 * @link http://php.net/manual/en/dateperiod.construct.php
	 * @see DatePeriod::__construct()
	 */
	public function __construct( ...$params )
	{
		parent::__construct( new IteratorIterator( new DatePeriod( ...$params ) ) );
	}

	/**
	 * Method overloading
	 *
	 * @throws BadMethodCallException
	 * 
	 * @param string $name
	 * @param array $noop
	 * @return self
	 */
	public function __call( string $name, array $noop ) : self
	{

		switch( $name )
		{

			case 'monday'   :
			case 'tuesday'  :
			case 'wednesday':
			case 'thursday' :
			case 'friday'   :
			case 'saturday' :
			case 'sunday'   :

				$this->_dayFilter[ ucfirst( $name ) ] = true;
				break;

			case 'weekdays':

				$this->monday()->tuesday()->wednesday()->thursday()->friday();
				break;

			case 'weekends':

				$this->saturday()->sunday();
				break;

			case 'am':
			case 'pm':

				$this->_meridiemFilter[ $name ] = true;
				break;

			case 'january'   :
			case 'february'  :
			case 'march'     :
			case 'april'     :
			case 'may'       :
			case 'june'      :
			case 'july'      :
			case 'august'    :
			case 'september' :
			case 'october'   :
			case 'november'  :
			case 'december'  :

				$this->_monthFilter[ ucfirst( $name ) ] = true;
				break;

			default:

				throw new BadMethodCallException( "Call to undefined method $name" );

		}

		return $this;
	}

	/**
	 * Given the current DateTime object, check if it matches a user filter
	 * 
	 * @param DateTime $current
	 * @return bool
	 */
	private function _userFilterMatches( DateTime $current ) : bool
	{

		foreach( $this->_userFilter as $filter )
		{

			if( $filter( $current ) )
				return true;

		}

		return false;
	}

	/**
	 * {@inheritDoc}
	 * @see FilterIterator::accept()
	 */
	public function accept() : bool
	{
		$current = $this->current();

		if( $this->_dayFilter      && !isset( $this->_dayFilter[      $current->format( 'l' ) ] ) ) return false;
		if( $this->_meridiemFilter && !isset( $this->_meridiemFilter[ $current->format( 'a' ) ] ) ) return false;
		if( $this->_monthFilter    && !isset( $this->_monthFilter[    $current->format( 'F' ) ] ) ) return false;
		if( $this->_userFilter     && !$this->_userFilterMatches(     $current                  ) ) return false;

		return true;
	}

	/**
	 * Add one or more custom filters to control which DateTime
	 * objects of DatePeriod will be interated
	 * 
	 * @param callable $filter
	 * <div>Invoked with the current DateTime object and is expected to return a boolean value to indicate whether it should be iterated.</div>
	 * 
	 * @param callable ...$filters
	 * @return self
	 */
	public function filter( callable $filter, callable ...$filters ) : self
	{
		array_push( $this->_userFilter, $filter, ...$filters );

		return $this;
	}

	/**
	 * Return the DatePeriod constructed during instantiation
	 * 
	 * @return DatePeriod
	 */
	public function getDatePeriod() : DatePeriod
	{
		return $this->getInnerIterator()
		            ->getInnerIterator()
		;
	}

}