myclabs/deep-copy

Create deep copies (clones) of your objects

1.8.1 2018-06-11 23:09 UTC

README

DeepCopy helps you create deep copies (clones) of your objects. It is designed to handle cycles in the association graph.

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Table of Contents

  1. Installation
  2. Why
    1. Using simply clone
    2. Overridding __clone()
    3. With DeepCopy
  3. Usage
  4. Going further
    1. Matchers
      1. Property name
      2. Specific property
      3. Type
    2. Filters
      1. SetNullFilter
      2. KeepFilter
      3. DoctrineCollectionFilter
      4. DoctrineEmptyCollectionFilter
      5. DoctrineProxyFilter
      6. ReplaceFilter
      7. ShallowCopyFilter
  5. Contributing
    1. Tests

Installation

With Composer:

composer require myclabs/deep-copy

Why?

  • How do you create copies of your objects?
$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() and implement the behavior yourself.

  • But how do you handle cycles in the association graph?

Now you're in for a big mess :(

association graph

Using simply clone

Using clone

Overridding __clone()

Overridding __clone

With DeepCopy

With DeepCopy

Usage

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:

use function DeepCopy\deep_copy;

$copy = deep_copy($var);

Alternatively, you can create your own DeepCopy instance to configure it differently for example:

use DeepCopy\DeepCopy;

$copier = new DeepCopy(true);

$copy = $copier->copy($var);

Or you may want to roll your own deep copy function:

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 by adding filters:

$copier = new DeepCopy();
$copier->addFilter($filter, $matcher);

During the copy process, when a property is matched by a matcher, then the filter associated to this matcher is applied. By default, when a filter is applied this stops the process, i.e. the next matcher-filter pair will not be checked, unless the filter is implemented as a chainable filter.

Some generic filters and matchers are already provided.

Matchers

  • Matcher applies on a object attribute
  • TypeMatcher applies on any element found in graph, including array elements

Property name

The PropertyNameMatcher will match a property by its name:

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:

use DeepCopy\Matcher\PropertyMatcher;

// Will apply a filter to the property "id" of any instances 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() function):

use DeepCopy\TypeMatcher\TypeMatcher;
use Doctrine\Common\Collections\Collection;

// Will apply a filter to any object that is an instance of Doctrine\Common\Collections\Collection
$matcher = new TypeMatcher(Collection::class);

Filters

Except a few exceptions (when the filter is a chainable filter like DoctrineProxyFilter), matching a filter will stop the chain of filters (i.e. the next ones will not be applied).

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:

use DeepCopy\DeepCopy;
use DeepCopy\Matcher\PropertyNameMatcher;
use DeepCopy\Filter\SetNullFilter;

$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):

use DeepCopy\DeepCopy;
use DeepCopy\Filter\KeepFilter;
use DeepCopy\Matcher\PropertyMatcher;

$copier = new DeepCopy();
$copier->addFilter(
    new KeepFilter(),
    new PropertyMatcher(MyClass::class, 'category')
);

$copy = $copier->copy($object); // $object is an instance of MyClass
// $copy->category has not been touched

DoctrineCollectionFilter (filter)

This filters allows to copy a Doctrine entity:

use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineCollectionFilter;
use DeepCopy\Matcher\PropertyTypeMatcher;
use Doctrine\Common\Collections\Collection;

$copier = new DeepCopy();
$copier->addFilter(
    new DoctrineCollectionFilter(),
    new PropertyTypeMatcher(Collection::class)
);

$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 this filter:

use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineEmptyCollectionFilter;
use DeepCopy\Matcher\PropertyMatcher;

$copier = new DeepCopy();
$copier->addFilter(
    new DoctrineEmptyCollectionFilter(),
    new PropertyMatcher(MyClass::class, '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 this filter 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!

This filter won't stop the chain of filters (i.e. the next ones may be applied).

use DeepCopy\DeepCopy;
use DeepCopy\Filter\Doctrine\DoctrineProxyFilter;
use DeepCopy\Filter\SetNullFilter;
use DeepCopy\Matcher\Doctrine\DoctrineProxyMatcher;
use DeepCopy\Matcher\PropertyNameMatcher;

$copier = new DeepCopy();
$copier->addFilter(new DoctrineProxyFilter(), new DoctrineProxyMatcher());
$copier->addFilter(new SetNullFilter(), new PropertyNameMatcher('id'));

$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:
use DeepCopy\DeepCopy;
use DeepCopy\Filter\ReplaceFilter;
use DeepCopy\Matcher\PropertyMatcher;

$copier = new DeepCopy();
$copier->addFilter(
    new ReplaceFilter(
        function ($currentValue): string {
            return $currentValue . ' (copy)'
        }
    ),
    new PropertyMatcher(MyClass::class, 'title')
);

$copy = $copier->copy($object); // $object is an instance of MyClass

// $copy->title will contain the data returned by the callback, e.g. 'The title (copy)'
  1. If you want to replace whole element:
use DeepCopy\DeepCopy;
use DeepCopy\TypeFilter\ReplaceFilter;
use DeepCopy\TypeMatcher\TypeMatcher;

$copier = new DeepCopy();
$copier->addFilter(
    new ReplaceFilter(
        function (MyClass $myClass): string {
            return get_class($myClass)
        }
    ),
    new TypeMatcher(MyClass::class)
);

$copy = $copier->copy([new MyClass, 'some string', new MyClass]);

// $copy will contain ['MyClass', 'some string', 'MyClass']

ShallowCopyFilter (type filter)

Stop DeepCopy from recursively copying element, using standard clone instead:

use DeepCopy\DeepCopy;
use DeepCopy\TypeFilter\ShallowCopyFilter;
use DeepCopy\TypeMatcher\TypeMatcher;
use Mockery as m;

$copier = new DeepCopy();
$copier->addTypeFilter(
	new ShallowCopyFilter,
	new TypeMatcher(m\MockInterface::class)
);

$myServiceWithMocks = new MyService(
    m::mock(MyDependency1::class),
    m::mock(MyDependency2::class)
);

$copy = $copier->copy($myServiceWithMocks)
// All mocks will be just cloned, not deep copied

Contributing

This package is distributed under the MIT license.

Tests

Running the tests is simple:

vendor/bin/phpunit