Note that AppendIterator will segfault when iterating over an empty generator. Do not use AppendIterator in conjunction with generators.
https://3v4l.org/YC68k
https://bugs.php.net/bug.php?id=71436
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
An Iterator that iterates over several iterators one after the other.
Note that AppendIterator will segfault when iterating over an empty generator. Do not use AppendIterator in conjunction with generators.
https://3v4l.org/YC68k
https://bugs.php.net/bug.php?id=71436
joshdifabio is technically correct, but I don't see this as a bug. You can't rewind a generator and thats what append iterator does.
If you want to use AppendIterator with Generators just wrap them with NoRewindIterator:
<?php
function foo() {
foreach ([] as $foo) {
yield $foo;
}
}
$append = new AppendIterator();
$append->append(new NoRewindIterator(foo()));
var_dump(iterator_to_array($append));
https://3v4l.org/pgiXB
In many cases, especially for streaming sources, Generators are way more efficient. I noticed that the AppendIterator buffers the entire "inner iterator".
<?php
/**
* This appends $next iterator to $iterator.
*/
function append_iterators(...$iterators){
foreach($iterators as $iterator)
foreach($iterator as $row)
yield($row);
}
/**
* Merge iterator takes one first from each iterator until
* every iterator is empty.
*/
function merge_iterators(....$its) {
$numberOfIts = sizeof($its);
while($numberOfIts > 0) {
$iterator = array_shift($its);
yield($iterator->current());
$iterator->next();
if($iterator->valid())
$its[] = $iterator;
else
$numberOfIts--;
}
});
?>
$append_iterator = new \AppendIterator();
$generator = ReportModel::come_generator();
foreach ($errors as $value)
{
//If first $value not empty, generator is not empty.
if(!empty($value))
{
$append_iterator->append($errors);
//break out of loop after appending.
break;
}
}
Updated code.
I could not find how to edit a note :/
Preventing segfault if empty generator.
<?php
$append_iterator = new \AppendIterator();
$generator = ReportModel::come_generator();
// Only works if first value in generator is not empty
// useful when yielding arrays
foreach ($append_iterator as $value)
{
//If first $value not empty, generator is not empty.
if(!empty($value))
{
$append_iterator->append($errors);
//break out of loop after appending.
break;
}
}
Updated code.
I could not find how to edit a note :/
Preventing segfault if empty generator.
<?php
$append_iterator = new \AppendIterator();
$generator = some_generator();
// Only works if first value in generator is not empty
// useful when yielding arrays
foreach ($generator as $value)
{
//If first $value not empty, generator is not empty.
if(!empty($value))
{
$append_iterator->append($generator );
//break out of loop after appending.
break;
}
}