symfony/polyfill-deepclone

Symfony polyfill for the deepclone extension

v1.34.0 2026-04-10 16:19 UTC

Requires

• php: >=8.1

Suggests

• ext-deepclone: For best performance

Provides

• ext-deepclone: *

MIT

• Nicolas Grekas
• Symfony Community

• compatibility
• portable
• polyfill
• shim
• deepclone

README

This package provides a pure-PHP implementation of the functions and exception classes from the deepclone extension:

• deepclone_to_array(mixed $value, ?array $allowedClasses = null): array — converts any serializable PHP value graph into a pure array (only scalars and nested arrays, no objects).
• deepclone_from_array(array $data, ?array $allowedClasses = null): mixed — rebuilds the value graph from the array, preserving object identity, references, cycles, and private property state.
• DeepClone\NotInstantiableException and DeepClone\ClassNotFoundException

When the native deepclone extension is loaded, this polyfill does nothing — the extension provides the same functions 4–5× faster.

The array representation preserves PHP's copy-on-write for strings and scalar arrays, making repeated cloning of a prototype significantly more memory efficient than unserialize(serialize()). It also serves as a cache-friendly serialization format: when dumped via var_export() into a .php file, OPcache maps the array into shared memory, making deserialization essentially free.

This is the same wire format used by Symfony's VarExporter\DeepCloner.

More information can be found in the main Polyfill README.

License

This library is released under the MIT license.