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# DeepCopy
DeepCopy helps you create deep copies (clones) of your objects. It is designed to handle cycles in the association graph.
[](https://packagist.org/packages/myclabs/deep-copy)
[](https://github.com/myclabs/DeepCopy/actions)
## Table of Contents
1. [How](#how)
1. [Why](#why)
1. [Using simply `clone`](#using-simply-clone)
1. [Overriding `__clone()`](#overriding-__clone)
1. [With `DeepCopy`](#with-deepcopy)
1. [How it works](#how-it-works)
1. [Going further](#going-further)
1. [Matchers](#matchers)
1. [Property name](#property-name)
1. [Specific property](#specific-property)
1. [Type](#type)
1. [Filters](#filters)
1. [`SetNullFilter`](#setnullfilter-filter)
1. [`KeepFilter`](#keepfilter-filter)
1. [`DoctrineCollectionFilter`](#doctrinecollectionfilter-filter)
1. [`DoctrineEmptyCollectionFilter`](#doctrineemptycollectionfilter-filter)
1. [`DoctrineProxyFilter`](#doctrineproxyfilter-filter)
1. [`ReplaceFilter`](#replacefilter-type-filter)
1. [`ShallowCopyFilter`](#shallowcopyfilter-type-filter)
1. [Edge cases](#edge-cases)
1. [Contributing](#contributing)
1. [Tests](#tests)
## How?
Install with Composer:
```
composer require myclabs/deep-copy
```
Use it:
```php
use DeepCopy\DeepCopy;
$copier = new DeepCopy();
$myCopy = $copier->copy($myObject);
```
## Why?
- How do you create copies of your objects?
```php
$myCopy = clone $myObject;
```
- How do you create **deep** copies of your objects (i.e. copying also all the objects referenced in the properties)?
You use [`__clone()`](http://www.php.net/manual/en/language.oop5.cloning.php#object.clone) and implement the behavior
yourself.
- But how do you handle **cycles** in the association graph?
Now you're in for a big mess :(
### Using simply `clone`
### Overriding `__clone()`
### With `DeepCopy`
## How it works
DeepCopy recursively traverses all the object's properties and clones them. To avoid cloning the same object twice it
keeps a hash map of all instances and thus preserves the object graph.
To use it:
```php
use function DeepCopy\deep_copy;
$copy = deep_copy($var);
```
Alternatively, you can create your own `DeepCopy` instance to configure it differently for example:
```php
use DeepCopy\DeepCopy;
$copier = new DeepCopy(true);
$copy = $copier->copy($var);
```
You may want to roll your own deep copy function:
```php
namespace Acme;
use DeepCopy\DeepCopy;
function deep_copy($var)
{
static $copier = null;
if (null === $copier) {
$copier = new DeepCopy(true);
}
return $copier->copy($var);
}
```
## Going further
You can add filters to customize the copy process.
The method to add a filter is `DeepCopy\DeepCopy::addFilter($filter, $matcher)`,
with `$filter` implementing `DeepCopy\Filter\Filter`
and `$matcher` implementing `DeepCopy\Matcher\Matcher`.
We provide some generic filters and matchers.
### Matchers
- `DeepCopy\Matcher` applies on a object attribute.
- `DeepCopy\TypeMatcher` applies on any element found in graph, including array elements.
#### Property name
The `PropertyNameMatcher` will match a property by its name:
```php
use DeepCopy\Matcher\PropertyNameMatcher;
// Will apply a filter to any property of any objects named "id"
$matcher = new PropertyNameMatcher('id');
```
#### Specific property
The `PropertyMatcher` will match a specific property of a specific class:
```php
use DeepCopy\Matcher\PropertyMatcher;
// Will apply a filter to the property "id" of any objects of the class "MyClass"
$matcher = new PropertyMatcher('MyClass', 'id');
```
#### Type
The `TypeMatcher` will match any element by its type (instance of a class or any value that could be parameter of
[gettype()](http://php.net/manual/en/function.gettype.php) function):
```php
use DeepCopy\TypeMatcher\TypeMatcher;
// Will apply a filter to any object that is an instance of Doctrine\Common\Collections\Collection
$matcher = new TypeMatcher('Doctrine\Common\Collections\Collection');
```
### Filters
- `DeepCopy\Filter` applies a transformation to the object attribute matched by `DeepCopy\Matcher`
- `DeepCopy\TypeFilter` applies a transformation to any element matched by `DeepCopy\TypeMatcher`
By design, matching a filter will stop the chain of filters (i.e. the next ones will not be applied).
Using the ([`ChainableFilter`](#chainablefilter-filter)) won't stop the chain of filters.
#### `SetNullFilter` (filter)
Let's say for example that you are copying a database record (or a Doctrine entity), so you want the copy not to have
any ID:
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\SetNullFilter;
use DeepCopy\Matcher\PropertyNameMatcher;
$object = MyClass::load(123);
echo $object->id; // 123
$copier = new DeepCopy();
$copier->addFilter(new SetNullFilter(), new PropertyNameMatcher('id'));
$copy = $copier->copy($object);
echo $copy->id; // null
```
#### `KeepFilter` (filter)
If you want a property to remain untouched (for example, an association to an object):
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\KeepFilter;
use DeepCopy\Matcher\PropertyMatcher;
$copier = new DeepCopy();
$copier->addFilter(new KeepFilter(), new PropertyMatcher('MyClass', 'category'));
$copy = $copier->copy($object);
// $copy->category has not been touched
```
#### `ChainableFilter` (filter)
If you use cloning on proxy classes, you might want to apply two filters for:
1. loading the data
2. applying a transformation
You can use the `ChainableFilter` as a decorator of the proxy loader filter, which won't stop the chain of filters (i.e.
the next ones may be applied).
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\ChainableFilter;
use DeepCopy\Filter\Doctrine\DoctrineProxyFilter;
use DeepCopy\Filter\SetNullFilter;
use DeepCopy\Matcher\Doctrine\DoctrineProxyMatcher;
use DeepCopy\Matcher\PropertyNameMatcher;
$copier = new DeepCopy();
$copier->addFilter(new ChainableFilter(new DoctrineProxyFilter()), new DoctrineProxyMatcher());
$copier->addFilter(new SetNullFilter(), new PropertyNameMatcher('id'));
$copy = $copier->copy($object);
echo $copy->id; // null
```
#### `DoctrineCollectionFilter` (filter)
If you use Doctrine and want to copy an entity, you will need to use the `DoctrineCollectionFilter`:
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineCollectionFilter;
use DeepCopy\Matcher\PropertyTypeMatcher;
$copier = new DeepCopy();
$copier->addFilter(new DoctrineCollectionFilter(), new PropertyTypeMatcher('Doctrine\Common\Collections\Collection'));
$copy = $copier->copy($object);
```
#### `DoctrineEmptyCollectionFilter` (filter)
If you use Doctrine and want to copy an entity who contains a `Collection` that you want to be reset, you can use the
`DoctrineEmptyCollectionFilter`
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineEmptyCollectionFilter;
use DeepCopy\Matcher\PropertyMatcher;
$copier = new DeepCopy();
$copier->addFilter(new DoctrineEmptyCollectionFilter(), new PropertyMatcher('MyClass', 'myProperty'));
$copy = $copier->copy($object);
// $copy->myProperty will return an empty collection
```
#### `DoctrineProxyFilter` (filter)
If you use Doctrine and use cloning on lazy loaded entities, you might encounter errors mentioning missing fields on a
Doctrine proxy class (...\\\_\_CG\_\_\Proxy).
You can use the `DoctrineProxyFilter` to load the actual entity behind the Doctrine proxy class.
**Make sure, though, to put this as one of your very first filters in the filter chain so that the entity is loaded
before other filters are applied!**
We recommend to decorate the `DoctrineProxyFilter` with the `ChainableFilter` to allow applying other filters to the
cloned lazy loaded entities.
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineProxyFilter;
use DeepCopy\Matcher\Doctrine\DoctrineProxyMatcher;
$copier = new DeepCopy();
$copier->addFilter(new ChainableFilter(new DoctrineProxyFilter()), new DoctrineProxyMatcher());
$copy = $copier->copy($object);
// $copy should now contain a clone of all entities, including those that were not yet fully loaded.
```
#### `ReplaceFilter` (type filter)
1. If you want to replace the value of a property:
```php
use DeepCopy\DeepCopy;
use DeepCopy\Filter\ReplaceFilter;
use DeepCopy\Matcher\PropertyMatcher;
$copier = new DeepCopy();
$callback = function ($currentValue) {
return $currentValue . ' (copy)'
};
$copier->addFilter(new ReplaceFilter($callback), new PropertyMatcher('MyClass', 'title'));
$copy = $copier->copy($object);
// $copy->title will contain the data returned by the callback, e.g. 'The title (copy)'
```
2. If you want to replace whole element:
```php
use DeepCopy\DeepCopy;
use DeepCopy\TypeFilter\ReplaceFilter;
use DeepCopy\TypeMatcher\TypeMatcher;
$copier = new DeepCopy();
$callback = function (MyClass $myClass) {
return get_class($myClass);
};
$copier->addTypeFilter(new ReplaceFilter($callback), new TypeMatcher('MyClass'));
$copy = $copier->copy([new MyClass, 'some string', new MyClass]);
// $copy will contain ['MyClass', 'some string', 'MyClass']
```
The `$callback` parameter of the `ReplaceFilter` constructor accepts any PHP callable.
#### `ShallowCopyFilter` (type filter)
Stop *DeepCopy* from recursively copying element, using standard `clone` instead:
```php
use DeepCopy\DeepCopy;
use DeepCopy\TypeFilter\ShallowCopyFilter;
use DeepCopy\TypeMatcher\TypeMatcher;
use Mockery as m;
$this->deepCopy = new DeepCopy();
$this->deepCopy->addTypeFilter(
new ShallowCopyFilter,
new TypeMatcher(m\MockInterface::class)
);
$myServiceWithMocks = new MyService(m::mock(MyDependency1::class), m::mock(MyDependency2::class));
// All mocks will be just cloned, not deep copied
```
## Edge cases
The following structures cannot be deep-copied with PHP Reflection. As a result they are shallow cloned and filters are
not applied. There is two ways for you to handle them:
- Implement your own `__clone()` method
- Use a filter with a type matcher
## Contributing
DeepCopy is distributed under the MIT license.
### Tests
Running the tests is simple:
```php
vendor/bin/phpunit
```
### Support
Get professional support via [the Tidelift Subscription](https://tidelift.com/subscription/pkg/packagist-myclabs-deep-copy?utm_source=packagist-myclabs-deep-copy&utm_medium=referral&utm_campaign=readme).
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