dart_lz4 library

Pure Dart LZ4 and LZ4HC APIs.

This library provides:

• LZ4 block compression/decompression.
• LZ4 frame encode/decode (including skippable frames).
• Streaming frame encode/decode as StreamTransformers.

All APIs are Uint8List-based and are intended to work on all Dart platforms, including Web.

Classes

Lz4FrameInfo

Metadata about an LZ4 frame.

Lz4FrameOptions

Options controlling LZ4 frame encoding.

Lz4HcOptions

Options for tuning LZ4 HC (High Compression) mode.

Enums

Lz4CompressionLevel

Compression level for lz4Compress.

Lz4FrameBlockSize

Maximum LZ4 frame block size.

Lz4FrameCompression

Compression mode used for each LZ4 frame block.

Functions

lz4Compress(Uint8List src, {Lz4CompressionLevel level = Lz4CompressionLevel.fast, int acceleration = 1, Lz4HcOptions? hcOptions}) → Uint8List

Compresses src into an LZ4 block.

lz4CompressWithSize(Uint8List src, {Lz4CompressionLevel level = Lz4CompressionLevel.fast, int acceleration = 1}) → Uint8List

Compresses src into an LZ4 block with the decompressed size prepended.

lz4Decompress(Uint8List src, {required int decompressedSize}) → Uint8List

Decompresses an LZ4 block src into a new Uint8List.

lz4DecompressWithSize(Uint8List src) → Uint8List

Decompresses an LZ4 block that was compressed with lz4CompressWithSize.

lz4FrameDecode(Uint8List src, {int? maxOutputBytes, Lz4DictionaryResolver? dictionaryResolver}) → Uint8List

Decodes one or more concatenated LZ4 frames from src.

lz4FrameDecoder({int? maxOutputBytes, Lz4DictionaryResolver? dictionaryResolver}) → StreamTransformer<List<int>, List<int>>

Returns a StreamTransformer that decodes LZ4 frames from a byte stream.

lz4FrameEncode(Uint8List src, {int acceleration = 1, Uint8List? dictionary}) → Uint8List

Encodes src as an LZ4 frame.

lz4FrameEncoder({int acceleration = 1, Uint8List? dictionary}) → StreamTransformer<List<int>, List<int>>

Returns a StreamTransformer that encodes bytes into a single LZ4 frame.

lz4FrameEncoderWithOptions({required Lz4FrameOptions options, Uint8List? dictionary}) → StreamTransformer<List<int>, List<int>>

Returns a StreamTransformer that encodes bytes into a single LZ4 frame using the provided options.

lz4FrameEncodeWithOptions(Uint8List src, {required Lz4FrameOptions options, Uint8List? dictionary}) → Uint8List

Encodes src as an LZ4 frame using the provided options.

lz4FrameInfo(Uint8List src) → Lz4FrameInfo

Parses the header of an LZ4 frame from src and returns its metadata.

lz4LegacyEncode(Uint8List src, {int acceleration = 1}) → Uint8List

Encodes src as a legacy LZ4 frame (magic 0x184C2102).

lz4SkippableEncode(Uint8List data, {int index = 0}) → Uint8List

Encodes a skippable frame containing data.

Typedefs

Lz4DictionaryResolver = Uint8List? Function(int dictId)

Callback to resolve a dictionary by its ID.

Exceptions / Errors

Lz4CorruptDataException

Thrown when the compressed data is corrupt (e.g. checksum mismatch, invalid block).

Lz4Exception

Base class for all LZ4-related exceptions.

Lz4FormatException

Thrown when the LZ4 frame format is invalid (e.g. bad magic number, invalid header).

Lz4OutputLimitException

Thrown when the output buffer is too small to contain the uncompressed data.

Lz4UnsupportedFeatureException

Thrown when a feature is not supported by this implementation (e.g. unknown version).