wmde/traversable-iterator

Turn Traversable objects into Iterators. Fixed version of the native IteratorIterator

Traversable Iterator

, _(*1)

Iterator that can be constructed from Traversable objects., _(*2)

Can be seen as a fixed version of IteratorIterator (which is used internally). IteratorIterator behaves in unexpected ways when constructed from an IteratorAggregate: it only calls getIterator once rather than once per iteration, which is what happens when you traverse the IteratorAggregate directly. In other words: looping over an IteratorIterator that contains a IteratorAggregate yields different behaviour than looping over the IteratorAggregate itself. This is unexpected and can be problematic. For instance when the IteratorAggregate contains a Generator (which happens often), looping over the IteratorIterator more than once will cause an error due to the Generator not being rewindable., _(*3)

Example of how IteratorIterator fails:, _(*4)

$iteratorAggregate = new class() implements \IteratorAggregate {
    public function getIterator() {
        yield 'a';
        yield 'b';
        yield 'c';
    }
}

$iterator = new IteratorIterator( $iteratorAggregate );

foreach ( $iterator as $value ) {}
foreach ( $iterator as $value ) {} // Exception: Cannot rewind a generator that was already run

This exception, and more generally difference in behaviour, does not occur when using TraversableIterator., _(*5)

Installation

To add this package as a local, per-project dependency to your project, simply add a dependency on wmde/traversable-iterator to your project's composer.json file. Here is a minimal example of a composer.json file that just defines a dependency on Traversable Iterator 1.x:, _(*6)

{
    "require": {
        "wmde/traversable-iterator": "~1.0"
    }
}

Usage

Running the tests

For a full CI run, _(*7)

composer ci

For tests only, _(*8)

composer test

For style checks only, _(*9)

composer cs

Release notes

1.0.0 (2017-06-17)

• Initial release