Raw deflate with a preset dictionary, from ext-zlib on any ordinary host.
The dictionary is worth more than the algorithm here: measured on Drupal-shaped data, gzip -9 reaches 3.52x standalone and delta coding against the previous version reaches 63.70x. Delta coding is "hand the previous version to the compressor as its dictionary", so every codec reporting no dictionary support meant every frame anchored and the store kept full copies.
gzdeflate() cannot carry a dictionary but deflate_init() can. The incremental zlib API has
taken a dictionary option since PHP 7.0, and ext-zlib is already a hard requirement of this
package, so a VPS, a container and a shared host all get this codec with nothing installed. That
is the whole mechanism; ext-zstd, ext-brotli and a zstd binary stay optional upgrades.
The host bridge is a fallback for runtimes that lack the incremental API, not the mechanism.
A PHP built for a JavaScript host - a Worker deployment compiled to WASM - can ship without
deflate_init() while still being able to deflate; such a host installs a function this codec
calls instead. Neither path changes the bytes: both emit raw deflate, so a frame written through
one is readable through the other.
A host with neither leaves this codec unavailable and the registry falls back, the same contract
every other codec here follows. id() is stable and recorded in the frame header, so a store
stays readable in the sense that matters: a host that cannot decode reports why rather than
returning damaged bytes.
levels() : array{min: int, max: int, default: int, fast: int, dense: int}
The compression levels this codec accepts.
The usable range, the default, the level to use on the flush path where throughput matters, and the level to use during compaction where ratio matters.
compress(string $data, ?int $level = null, ?string $dictionary = null) : string
Compresses a buffer.
A NULL or empty dictionary is a plain deflate rather than an error: the caller decides whether a frame anchors, and refusing here would make the anchor frame of every chain fail.
| string | $data | The bytes to compress. An empty string compresses to an empty string, so that an absent payload never becomes a non-empty frame. |
| ?int | $level | A level within CompressionCodecInterface::levels(), or NULL for the default. |
| ?string | $dictionary | Raw dictionary bytes, or NULL. Ignored by codecs that report no dictionary support, so a caller never has to branch on it. |
The compressed bytes.
decompress(string $data, ?string $dictionary = null) : string
Decompresses a buffer.
Raises rather than returning partial output. A frame decompressed against the WRONG dictionary does not error in zlib, it produces plausible garbage, so the caller has to hand back the same bytes it compressed with; the chain in ObjectStore is what guarantees that.
| string | $data | The compressed bytes. |
| ?string | $dictionary | The same dictionary bytes used to compress, or NULL. |
The original bytes.
native(string $data, string $dictionary, int $level) : string|false
Deflates against a preset dictionary using ext-zlib.
ZLIB_ENCODING_RAW rather than the zlib container, so the output is the same raw deflate stream
gzdeflate() produces and an anchor frame and a delta frame stay one format.
| string | $data | The bytes to compress. |
| string | $dictionary | The preset dictionary. |
| int | $level | The compression level. |
The deflated bytes, or FALSE.
nativeInflate(string $data, string $dictionary) : string|false
Inflates against a preset dictionary using ext-zlib.
| string | $data | The bytes to expand. |
| string | $dictionary | The preset dictionary the bytes were compressed against. |
The original bytes, or FALSE.
bridge(string $op, string $data, string $dictionary, int $level) : string|false
Calls the host function without naming it at compile time.
Only reached on a host without the incremental zlib API. No presence check here: the callers
pick this path precisely because the native one is absent, and assertAvailable() has already
established that one of the two exists. stubs/cfw.php is what gives the analyser the
signature, the same way the extension stubs beside it do.
| string | $op | Either "deflate" or "inflate". |
| string | $data | The bytes to transform. |
| string | $dictionary | The preset dictionary. |
| int | $level | The compression level; ignored when inflating. |
The transformed bytes, or FALSE.