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<?php
/**
* Convenience class for generating iterators from iterators.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @author Aaron Schulz
*/
/**
* Convenience class for generating iterators from iterators.
*
* @since 1.21
*/
class MappedIterator extends FilterIterator {
/** @var callable */
protected $vCallback;
/** @var callable */
protected $aCallback;
/** @var array */
protected $cache = array();
protected $rewound = false; // boolean; whether rewind() has been called
/**
* Build an new iterator from a base iterator by having the former wrap the
* later, returning the result of "value" callback for each current() invocation.
* The callback takes the result of current() on the base iterator as an argument.
* The keys of the base iterator are reused verbatim.
*
* An "accept" callback can also be provided which will be called for each value in
* the base iterator (post-callback) and will return true if that value should be
* included in iteration of the MappedIterator (otherwise it will be filtered out).
*
* @param Iterator|Array $iter
* @param callable $vCallback Value transformation callback
* @param array $options Options map (includes "accept") (since 1.22)
* @throws MWException
*/
public function __construct( $iter, $vCallback, array $options = array() ) {
if ( is_array( $iter ) ) {
$baseIterator = new ArrayIterator( $iter );
} elseif ( $iter instanceof Iterator ) {
$baseIterator = $iter;
} else {
throw new MWException( "Invalid base iterator provided." );
}
parent::__construct( $baseIterator );
$this->vCallback = $vCallback;
$this->aCallback = isset( $options['accept'] ) ? $options['accept'] : null;
}
public function next() {
$this->cache = array();
parent::next();
}
public function rewind() {
$this->rewound = true;
$this->cache = array();
parent::rewind();
}
public function accept() {
$value = call_user_func( $this->vCallback, $this->getInnerIterator()->current() );
$ok = ( $this->aCallback ) ? call_user_func( $this->aCallback, $value ) : true;
if ( $ok ) {
$this->cache['current'] = $value;
}
return $ok;
}
public function key() {
$this->init();
return parent::key();
}
public function valid() {
$this->init();
return parent::valid();
}
public function current() {
$this->init();
if ( parent::valid() ) {
return $this->cache['current'];
} else {
return null; // out of range
}
}
/**
* Obviate the usual need for rewind() before using a FilterIterator in a manual loop
*/
protected function init() {
if ( !$this->rewound ) {
$this->rewind();
}
}
}
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