CODEWITHSUNDEEP
phpspl
jcroll
jcroll

Reputation: 7165

PHP RecursiveIteratorIterator: Can you call getSubIterator() with a depth greater than your current depth?

When recursively iterating using an instance of \RecursiveIteratorIterator is it expected behaviour that in looking for a sub iterator of a depth greater than your current depth, it always returns null?

Please see: RecursiveIteratorIterator::getSubIterator

public RecursiveIterator RecursiveIteratorIterator::getSubIterator ([ int $level ] )

Example:

$innerIterator = new \RecursiveArrayIterator([/*a recursive array*/]);
$iterator = new \RecursiveIteratorIterator($innerIterator);

foreach ($iterator as $value) {
    $depth       = $iterator->getDepth();
    $parentDepth = $depth - 1;
    $childDepth  = $depth + 1;
    // returns \RecursiveArrayIterator
    $iterator->getSubIterator($depth);
    // returns null first iteration and \RecursiveArrayIterator thereafter
    $iterator->getSubIterator($parentDepth);
    // always returns null...should it?
    $iterator->getSubIterator($childDepth);
}

Upvotes: 1

Views: 681

Answers (1)

salathe
salathe

Reputation: 51950

The RecursiveIteratorIterator::getSubIterator() method's source code is short enough to be posted here, and is as good a place as any to find an answer.

/* {{{ proto RecursiveIterator RecursiveIteratorIterator::getSubIterator([int level])
   The current active sub iterator or the iterator at specified level */
SPL_METHOD(RecursiveIteratorIterator, getSubIterator)
{
    spl_recursive_it_object   *object = (spl_recursive_it_object*)zend_object_store_get_object(getThis() TSRMLS_CC);
    long  level = object->level;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &level) == FAILURE) {
        return;
    }
    if (level < 0 || level > object->level) {
        RETURN_NULL();
    }
    RETURN_ZVAL(object->iterators[level].zobject, 1, 0);
} /* }}} */

— From the PHP 5.5.14 source.

The key part for this question is the if statement:

if (level < 0 || level > object->level) {
    RETURN_NULL();
}

The code is pretty self-explanatory, but it is saying:

If the specified level is less than zero, or greater than the current object's level, return null.

Upvotes: 4

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