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rehfeld/comparator
==================

Helps you write concise array sorting callbacks for php's usort function

04PHP

Since Jan 18Pushed 11y ago1 watchersCompare

[ Source](https://github.com/rehfeldchris/comparator)[ Packagist](https://packagist.org/packages/rehfeld/comparator)[ RSS](/packages/rehfeld-comparator/feed)WikiDiscussions master Synced 1mo ago

READMEChangelogDependenciesVersions (1)Used By (0)

\#What is it

This class has some functionality that helps make custom sorting more concise. Normally, you probably use `usort()`everywhere, and all the callbacks that you write generally share 2 pieces of functionality:

1. some code that extracts the sorting value
2. some code that actually does comparisons upon the sorting value, to return -1, 0, or 1 in order to satisfy `usort()`.

This class tries to alleviate you from the duty of doing the comparisons - you just need to provide the code to extract the value. And in basic cases, it can mostly alleviate you of that duty too.

Instead of writing code that both extracts the value and then does comparisons:

```
usort($arrayOfUser, function(User $a, User $b) {
    // Code that extracts the sorting value
    $dateA = $a->getBirthdayAsDatetime();
    $dateB = $b->getBirthdayAsDatetime();

    // Code that compares the sorting value
    if ($dateA == $dateB) {
        return 0;
    }
    return $dateA < $dateB ? -1 : 1;
});

```

Just provide a function which produces the sorting value:

```
usort($arrayOfUser, Comparator::sortAscByValueExtractor(function(User $user) {
    return $user->getBirthdayAsDatetime();
}));

```

In this scenario, since the sort value can be extracted with a single method call, you could also do:

```
usort($arrayOfUser, Comparator::sortAscByMethod('getBirthdayAsDatetime'));

```

Convenience methods for sorting by an array key, a public object property, or a public method exist. But, the most powerful are the valueExtractor methods, because they let you use custom logic.

Another method that's included gives you the ability to sort using the same semantics that an sql order by clause uses. The following would sort the same way as the sql `... order by lastName asc, age desc, gender asc`

```
$arrayOfRows = [
    ['lastName' => 'smith', 'age' > 25, 'gender' => 'male'],
    ['lastName' => 'hax',   'age' > 33, 'gender' => 'male'],
];
usort($arrayOfRows, Comparator::tieBreaker(
    Comparator::sortAscByArrayKey('lastName'),
    Comparator::sortDescByArrayKey('age'),
    Comparator::sortAscByArrayKey('gender'),
));

```

\###Note This class internally uses the loose comparison operators `==` and `