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