The Iterator interface

The Iterator<Tv> interface ¶

(HHVM >= 2.5)

Introduction ¶

Interface for external iterators or objects that can be iterated themselves internally.

Interface synopsis ¶

Iterator<Tv> extends Traversable<Tv> {

/* Methods */

abstract public Tv current ( void )

abstract public mixed key ( void )

abstract public void next ( void )

abstract public void rewind ( void )

abstract public boolean valid ( void )

}

Examples ¶

Example #1 Basic usage

This example demonstrates in which order methods are called when using foreach with an iterator.

<?hh
class myIterator<Tv> implements Iterator<Tv> {
  private $position = 0;
  private $array = array(
    "firstelement",
    "secondelement",
    "lastelement",
  );  

  public function __construct() {
    $this->position = 0;
  }

  function rewind(): void {
    var_dump(__METHOD__);
    $this->position = 0;
  }

  function current(): Tv {
    var_dump(__METHOD__);
    return $this->array[$this->position];
  }

  function next(): void {
    var_dump(__METHOD__);
    ++$this->position;
  }

  function valid(): bool {
    var_dump(__METHOD__);
    return isset($this->array[$this->position]);
  }
}

$it = new myIterator;

foreach($it as $value) {
  var_dump($value);
  echo "\n";
}

The above example will output something similar to:

string(18) "myIterator::rewind"

string(17) "myIterator::valid"

string(19) "myIterator::current"

string(15) "myIterator::key"

string(12) "firstelement"

string(16) "myIterator::next"

string(17) "myIterator::valid"

string(19) "myIterator::current"

string(15) "myIterator::key"

string(13) "secondelement"

string(16) "myIterator::next"

string(17) "myIterator::valid"

string(19) "myIterator::current"

string(15) "myIterator::key"

string(11) "lastelement"

string(16) "myIterator::next"

string(17) "myIterator::valid"

Table of Contents ¶

·         Iterator<Tv>::current — Return the current element

·         Iterator<Tv>::key — Return the key of the current element

·         Iterator<Tv>::next — Move forward to next element

·         Iterator<Tv>::rewind — Rewind the Iterator to the first element

·         Iterator<Tv>::valid — Checks if current position is valid

Iterator<Tv>::current

(HHVM >= 2.5)

Iterator<Tv>::current — Return the current element

Description ¶

abstract public Tv Iterator<Tv>::current ( void )

Returns the current element.

Parameters ¶

This function has no parameters.

Return Values ¶

Can return any type.

Iterator<Tv>::key

(HHVM >= 2.5)

Iterator<Tv>::key — Return the key of the current element

Description ¶

abstract public mixed Iterator<Tv>::key ( void )

Returns NULL. Use KeyedIterator<Tk, Tv> for key-based iteration.

Parameters ¶

This function has no parameters.

Return Values ¶

Returns NULL

Errors/Exceptions ¶

Issues E_NOTICE on failure.

Iterator<Tv>::next

(HHVM >= 2.5)

Iterator<Tv>::next — Move forward to next element

Description ¶

abstract public void Iterator<Tv>::next ( void )

Moves the current position to the next element.

Note:

This method is called after each foreach loop.

Parameters ¶

This function has no parameters.

Return Values ¶

Any returned value is ignored.

Iterator<Tv>::rewind

(HHVM >= 2.5)

Iterator<Tv>::rewind — Rewind the Iterator to the first element

Description ¶

abstract public void Iterator<Tv>::rewind ( void )

Rewinds back to the first element of the Iterator.

Note:

This is the first method called when starting a foreach loop. It will not be executed after foreach loops.

Parameters ¶

This function has no parameters.

Return Values ¶

Any returned value is ignored.

erator<Tv>::valid

(HHVM >= 2.5)

Iterator<Tv>::valid — Checks if current position is valid

Description ¶

abstract public boolean Iterator<Tv>::valid ( void )

This method is called after Iterator::rewind() and Iterator::next() to check if the current position is valid.

Parameters ¶

This function has no parameters.

Return Values ¶

The return value will be casted to boolean and then evaluated. Returns TRUE on success or FALSE on failure.